OS-7520 OS-6778 broke IPv4 forwarding

OS-6878 mac_fix_cksum is incomplete
OS-7806 cannot move link from NGZ to GZ
Reviewed by: Patrick Mooney <patrick.mooney@joyent.com>
Reviewed by: Robert Mustacchi <rm@joyent.com>
Approved by: Robert Mustacchi <rm@joyent.com>

35 files changed, 2690 insertions, 403 deletions

diff --git a/usr/src/cmd/dlmgmtd/dlmgmt_door.c b/usr/src/cmd/dlmgmtd/dlmgmt_door.c
index 2bebaa24c3..647b919864 100644
--- a/usr/src/cmd/dlmgmtd/dlmgmt_door.c
+++ b/usr/src/cmd/dlmgmtd/dlmgmt_door.c
@@ -21,7 +21,7 @@
 
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright 2017 Joyent, Inc.
+ * Copyright 2019 Joyent, Inc.
  */
 
 /*
@@ -1248,21 +1248,6 @@ dlmgmt_setzoneid(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
 	}
 
 	if (oldzoneid != GLOBAL_ZONEID) {
-		if (newzoneid == GLOBAL_ZONEID && linkp->ll_onloan) {
-			/*
-			 * In this case we are attempting to assign a
-			 * loaned datalink from an NGZ to the GZ. We
-			 * can only reassign a loaned VNIC back to the
-			 * GZ when the zone is shutting down --
-			 * because otherwise the VNIC is in use by the
-			 * zone and will be busy. Leave the VNIC
-			 * loaned to the zone and return EBUSY to the
-			 * caller.
-			 */
-			err = EBUSY;
-			goto done;
-		}
-
 		if (zone_remove_datalink(oldzoneid, linkid) != 0) {
 			err = errno;
 			dlmgmt_log(LOG_WARNING, "unable to remove link %d from "
@@ -1272,6 +1257,7 @@ dlmgmt_setzoneid(void *argp, void *retp, size_t *sz, zoneid_t zoneid,
 
 		linkp->ll_onloan = B_FALSE;
 	}
+
 	if (newzoneid != GLOBAL_ZONEID) {
 		if (zone_add_datalink(newzoneid, linkid) != 0) {
 			err = errno;
diff --git a/usr/src/test/Makefile b/usr/src/test/Makefile
index fa57d36772..9756f02ef7 100644
--- a/usr/src/test/Makefile
+++ b/usr/src/test/Makefile
@@ -12,6 +12,7 @@
 #
 # Copyright (c) 2012 by Delphix. All rights reserved.
 # Copyright 2014 Garrett D'Amore <garrett@damore.org>
+# Copyright 2019 Joyent, Inc.
 #
 
 .PARALLEL: $(SUBDIRS)
@@ -20,6 +21,7 @@ SUBDIRS = \
 	crypto-tests \
 	elf-tests \
 	libc-tests \
+	net-tests \
 	os-tests \
 	smbclient-tests \
 	test-runner \
diff --git a/usr/src/test/net-tests/Makefile b/usr/src/test/net-tests/Makefile
new file mode 100644
index 0000000000..6536e70c59
--- /dev/null
+++ b/usr/src/test/net-tests/Makefile
@@ -0,0 +1,20 @@
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright 2019, Joyent Inc.
+#
+
+.PARALLEL: $(SUBDIRS)
+
+SUBDIRS = cmd config runfiles tests
+
+include $(SRC)/test/Makefile.com
diff --git a/usr/src/test/net-tests/cmd/Makefile b/usr/src/test/net-tests/cmd/Makefile
new file mode 100644
index 0000000000..b2770c84c6
--- /dev/null
+++ b/usr/src/test/net-tests/cmd/Makefile
@@ -0,0 +1,36 @@
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright 2019 Joyent, Inc.
+#
+include $(SRC)/Makefile.master
+
+ROOTOPTPKG = $(ROOT)/opt/net-tests
+ROOTBIN = $(ROOTOPTPKG)/bin
+PROGS = nettest
+CMDS = $(PROGS:%=$(ROOTBIN)/%)
+$(CMDS) := FILEMODE = 0555
+
+include $(SRC)/test/Makefile.com
+
+install: $(CMDS)
+
+clobber: clean
+	$(RM) $(CMDS)
+
+$(CMDS): $(ROOTBIN)
+
+$(ROOTBIN):
+	$(INS.dir)
+
+$(ROOTBIN)/%: %.ksh
+	$(INS.rename)
diff --git a/usr/src/test/net-tests/cmd/nettest.ksh b/usr/src/test/net-tests/cmd/nettest.ksh
new file mode 100644
index 0000000000..e7d0e78865
--- /dev/null
+++ b/usr/src/test/net-tests/cmd/nettest.ksh
@@ -0,0 +1,52 @@
+#!/usr/bin/ksh
+
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright 2019 Joyent, Inc.
+#
+
+export NET_TESTS="/opt/net-tests"
+runner="/opt/test-runner/bin/run"
+
+function fail
+{
+	echo $1 >&2
+	exit ${2:-1}
+}
+
+function find_runfile
+{
+	typeset distro=
+	if [[ -f $NET_TESTS/runfiles/default.run ]]; then
+		distro=default
+	fi
+
+	[[ -n $distro ]] && echo $NET_TESTS/runfiles/$distro.run
+}
+
+while getopts c: c; do
+	case $c in
+	'c')
+		runfile=$OPTARG
+		[[ -f $runfile ]] || fail "Cannot read file: $runfile"
+		;;
+	esac
+done
+shift $((OPTIND - 1))
+
+[[ -z $runfile ]] && runfile=$(find_runfile)
+[[ -z $runfile ]] && fail "Couldn't determine distro"
+
+$runner -c $runfile
+
+exit $?
diff --git a/usr/src/test/net-tests/config/Makefile b/usr/src/test/net-tests/config/Makefile
new file mode 100644
index 0000000000..c1d3f8c285
--- /dev/null
+++ b/usr/src/test/net-tests/config/Makefile
@@ -0,0 +1,38 @@
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright 2019 Joyent, Inc.
+#
+
+include $(SRC)/Makefile.master
+
+CFGS = ip_forwarding.config
+ROOTOPTPKG = $(ROOT)/opt/net-tests
+ROOTOPTPKGCFG = $(ROOT)/opt/net-tests/config
+ROOTOPTPKGDIRS = $(ROOTOPTPKG) $(ROOTOPTPKGCFG)
+FILES = $(CFGS:%=$(ROOTOPTPKGCFG)/%)
+$(FILES) := FILEMODE = 0555
+
+include $(SRC)/test/Makefile.com
+
+all: $(CFGS)
+
+install: $(ROOTOPTPKG) $(ROOTOPTPKGCFG) $(FILES)
+
+clobber: clean
+	$(RM) $(FILES)
+
+$(ROOTOPTPKGDIRS):
+	$(INS.dir)
+
+$(ROOTOPTPKGCFG)/%: % $(ROOTOPTPKGDIRS)
+	$(INS.file)
diff --git a/usr/src/test/net-tests/config/ip_forwarding.config b/usr/src/test/net-tests/config/ip_forwarding.config
new file mode 100644
index 0000000000..4a839cd49d
--- /dev/null
+++ b/usr/src/test/net-tests/config/ip_forwarding.config
@@ -0,0 +1,22 @@
+#!/usr/bin/ksh
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+
+#
+# Copyright 2019 Joyent, Inc.
+#
+
+#
+# See the tests/forwarding/README file for information about how to
+# configure and run the tests.
+#
+export NT_CLIENT=client_zone_name
+export NT_ROUTER=router_zone_name
+export NT_SERVER=server_zone_name
diff --git a/usr/src/test/net-tests/runfiles/Makefile b/usr/src/test/net-tests/runfiles/Makefile
new file mode 100644
index 0000000000..d50a8deebf
--- /dev/null
+++ b/usr/src/test/net-tests/runfiles/Makefile
@@ -0,0 +1,38 @@
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright 2019 Joyent, Inc.
+#
+include $(SRC)/Makefile.master
+
+SRCS = default.run
+ROOTOPTPKG = $(ROOT)/opt/net-tests
+RUNFILES = $(ROOTOPTPKG)/runfiles
+CMDS = $(SRCS:%=$(RUNFILES)/%)
+$(CMDS) := FILEMODE = 0444
+
+include $(SRC)/test/Makefile.com
+
+all: $(SRCS)
+
+install: $(CMDS)
+
+clobber: clean
+	$(RM) $(CMDS)
+
+$(CMDS): $(RUNFILES) $(SRCS)
+
+$(RUNFILES):
+	$(INS.dir)
+
+$(RUNFILES)/%: %
+	$(INS.file)
diff --git a/usr/src/test/net-tests/runfiles/default.run b/usr/src/test/net-tests/runfiles/default.run
new file mode 100644
index 0000000000..ff5a3cac6e
--- /dev/null
+++ b/usr/src/test/net-tests/runfiles/default.run
@@ -0,0 +1,29 @@
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright 2019 Joyent, Inc.
+#
+
+[DEFAULT]
+outputdir = /var/tmp/test_results
+quiet = False
+timeout = 60
+
+[/opt/net-tests/tests/forwarding]
+tests = [
+	'ip_fwd_no_cksum',
+	'ip_fwd_partial_cksum',
+	'ip_fwd_full_cksum',
+	'ip_fwd_partial_cksum_lso',
+	'ip_fwd_full_cksum_lso'
+	]
+user = root
diff --git a/usr/src/test/net-tests/tests/Makefile b/usr/src/test/net-tests/tests/Makefile
new file mode 100644
index 0000000000..2712d62751
--- /dev/null
+++ b/usr/src/test/net-tests/tests/Makefile
@@ -0,0 +1,42 @@
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright 2019 Joyent, Inc.
+#
+include $(SRC)/Makefile.master
+include $(SRC)/cmd/Makefile.cmd
+
+SUBDIRS = forwarding
+SCRIPTS = net_common
+ROOTOPTPKG = $(ROOT)/opt/net-tests
+TESTDIR = $(ROOTOPTPKG)/tests
+CMDS = $(SCRIPTS:%=$(TESTDIR)/%)
+FILEMODE=0444
+$(CMDS) := FILEMODE = 0555
+
+include $(SRC)/test/Makefile.com
+
+install: $(CMDS)
+
+clobber: clean
+	$(RM) $(CMDS)
+
+$(CMDS): $(TESTDIR)
+
+$(TESTDIR):
+	$(INS.dir)
+
+$(TESTDIR)/%: %
+	$(INS.file)
+
+$(TESTDIR)/%: %.ksh
+	$(INS.rename)
diff --git a/usr/src/test/net-tests/tests/forwarding/Makefile b/usr/src/test/net-tests/tests/forwarding/Makefile
new file mode 100644
index 0000000000..30a95b7fe9
--- /dev/null
+++ b/usr/src/test/net-tests/tests/forwarding/Makefile
@@ -0,0 +1,51 @@
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright 2019 Joyent, Inc.
+#
+include $(SRC)/Makefile.master
+include $(SRC)/cmd/Makefile.cmd
+
+ROOTOPTPKG = $(ROOT)/opt/net-tests
+TESTDIR = $(ROOTOPTPKG)/tests/forwarding
+
+PROG = \
+	ip_forwarding \
+	ip_fwd_no_cksum \
+	ip_fwd_partial_cksum \
+	ip_fwd_full_cksum \
+	ip_fwd_partial_cksum_lso \
+	ip_fwd_full_cksum_lso
+
+DOC = $(TESTDIR)/README
+
+CMDS = $(PROG:%=$(TESTDIR)/%)
+FILEMODE=0444
+$(CMDS) := FILEMODE = 0555
+
+include $(SRC)/test/Makefile.com
+
+install: $(CMDS) $(DOC)
+
+clobber: clean
+	$(RM) $(CMDS) $(DOC)
+
+$(CMDS) $(DOC): $(TESTDIR)
+
+$(TESTDIR):
+	$(INS.dir)
+
+$(TESTDIR)/%: %
+	$(INS.file)
+
+$(TESTDIR)/%: %.ksh
+	$(INS.rename)
diff --git a/usr/src/test/net-tests/tests/forwarding/README b/usr/src/test/net-tests/tests/forwarding/README
new file mode 100644
index 0000000000..626dbe55e4
--- /dev/null
+++ b/usr/src/test/net-tests/tests/forwarding/README
@@ -0,0 +1,124 @@
+Running
+-------
+
+* Create three native zones and start them.
+
+* Edit config/ip_forwarding.config, entering the names of the zones
+  you created.
+
+* Run /opt/net-tests/bin/nettest.
+
+Overview
+--------
+
+The tests in this directory test the IP forwarding path under several
+different variations. All tests require three zones. The tests use
+these three zones, along with the simnet driver, to emulate a real IP
+forwarding scenario involving multiple hosts. All tests verify that
+TCP, UDP, ICMP, IPv4/IPv6, and fragmented IPv4/IPv6 traffic can cross
+the IP forwarding datapath. All tests send traffic across both "the
+wire" (simnet) and the special MAC-loopback path. Each test differs in
+its emulation of various hardware offload features (which would
+typically be presented by real NICs). There is no emulation of Rx
+checksum offload; all packets will be software checksummed by IP
+input. In the future we may want to add variations where Rx checksum
+offload is in play as that's a typical feature provided by NICs.
+
+The diagram below gives a visual representation of the situation we
+are testing and shows how the test components relate to each other.
+
++----------------------------+          +----------------------------+
+|client host (ipft_nic0)     |          |server host (ipft_nic1)     |
+|                            |          | +------------------------+ |
+|  +----------------------+  |          | |router zone             | |
+|  |ipft_client0          |  |          | |                        | |
+|  |192.168.77.2          |<-+----+     | |+----------------------+| |
+|  |fd00:0:1:4d::2        |  |    |     | ||ipft_client_r0        || |
+|  +----------------------+  |   Wire --+->|192.168.77.1          || |
++----------------------------+          | ||fd00:0:1:4d::1        || |
+                                        | |+----------------------+| |
+                                        | |            ^           | |
+                                        | |            |           | |
+                                        | |     IP     |           | |
+                                        | | forwarding |           | |
+                                        | |            |           | |
+                                        | |            v           | |
+                                        | |+----------------------+| |
+                                        | ||ipft_server_r0        || |
+                                        | ||VLAN 5                || |
+                                  +-----+->|192.168.88.1          || |
+                                  |     | ||fd00:0:1:58::1        || |
+                                  |     | |+----------------------+| |
+                                  |     | +------------------------+ |
+                     MAC-loopback |     |                            |
+                                  |     | +------------------------+ |
+                                  |     | |server zone             | |
+                                  |     | |                        | |
+                                  |     | |+----------------------+| |
+                                  |     | ||ipft_server0          || |
+                                  |     | ||VLAN 5                || |
+                                  +-----+->|192.168.88.2          || |
+                                        | ||fd00:0:1:58::2        || |
+                                        | |+----------------------+| |
+                                        | +------------------------+ |
+                                        +----------------------------+
+
+Requirements
+------------
+
+* These tests are currently SmartOS specific as they rely on simnet
+  extensions only found in illumos-joyent.
+
+* The client and server zones must provide `/usr/bin/socat`. It would
+  be nice to use netcat but our native version is missing features
+  like connection timeout.
+
+* The user must both create and start the three required zones.
+
+* All three zones should be native zones.
+
+* You must edit the ip_forwarding.config file; providing it with the
+  names of the zones you have created.
+
+Files
+-----
+
+ip_fowarding
+
+	The main test script; it provides the logic for all the tests
+	below. The different test variations are controlled by options
+	and it takes the three zones as arguments. This script is also
+	easily run by hand if you want to bypass the test-runner
+	framework. The rest of the test sripts are meant for
+	consumption by the test-runner framework and are wrappers
+	around this script.
+
+ip_fwd_no_cksum
+
+	Tests IP forwarding with no hardware offloads on any of the
+	interfaces.
+
+ip_fwd_partial_cksum
+
+	Tests IP forwarding with partial Tx checksum offload and IPv4
+	header checksum offload enabled on both interfaces.
+
+ip_fwd_full_cksum
+
+	Tests IP forwarding with full Tx checksum offload and IPv4
+	header checksum offload enabled on both interfaces.
+
+ip_fwd_partial_cksum_lso
+
+	Tests IP forwarding with partial Tx checksum offload, IPv4
+	header checksum offload, and TCP LSO on both interfaces.
+
+ip_fwd_full_cksum_lso
+
+	Tests IP forwarding with full Tx checksum offload, IPv4 header
+	checksum offload, and TCP LSO on both interfaces.
+
+config/ip_forwarding.config
+
+	This file must be modified to contain the names of the zones
+	the user crated for running these tests.
\ No newline at end of file
diff --git a/usr/src/test/net-tests/tests/forwarding/ip_forwarding.ksh b/usr/src/test/net-tests/tests/forwarding/ip_forwarding.ksh
new file mode 100644
index 0000000000..74784fb494
--- /dev/null
+++ b/usr/src/test/net-tests/tests/forwarding/ip_forwarding.ksh
@@ -0,0 +1,444 @@
+#!/usr/bin/ksh
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+
+#
+# Copyright 2019 Joyent, Inc.
+#
+
+#
+# Usage:
+#
+#     ip_forwarding.ksh -flnpvu <client> <router> <server>
+#
+#     Where client, router, and server are the UUIDs of three native
+#     zones. The user must create and start these zones; but other
+#     than that there is no special configuration required for them.
+#
+#     -c	Run cleanup only.
+#
+#     -f	Full ULP hardware checksum.
+#
+#     -l	Hardware TCP LSO.
+#
+#     -n	No cleanup: the various artifacts created by this script will
+#               remain after execution.
+#
+#     -p	Partial ULP hardware checksum.
+#
+#     -u	Run UDP tests.
+#
+#     -v	Vebose mode.
+#
+
+if [[ -z $NET_TESTS ]]; then
+	echo "NET_TESTS not set" >&2
+	exit 1
+fi
+
+. $NET_TESTS/tests/net_common
+
+function cleanup
+{
+	rm -rf ${nt_tdirprefix}*
+	zlogin $nt_client rm -rf ${nt_tdirprefix}*
+	zlogin $nt_server rm -rf ${nt_tdirprefix}*
+
+	rm_route $nt_client $nt_server_ip $nt_server_subnet $nt_client_router_ip
+	rm_route $nt_server $nt_client_ip $nt_client_subnet $nt_server_router_ip
+	rm_route6 $nt_client $nt_server_ip6 $nt_server_subnet6 \
+		  $nt_client_router_ip6
+	rm_route6 $nt_server $nt_client_ip6 $nt_client_subnet6 \
+		  $nt_server_router_ip6
+
+	ip_fwd_disable $nt_router
+
+	delete_addr $nt_client ipft_client0 v4
+	delete_addr $nt_router ipft_client_r0 v4
+	delete_addr $nt_router ipft_server_r0 v4
+	delete_addr $nt_server ipft_server0 v4
+
+	delete_addr $nt_client ipft_client0 v6
+	delete_addr $nt_router ipft_client_r0 v6
+	delete_addr $nt_router ipft_server_r0 v6
+	delete_addr $nt_server ipft_server0 v6
+
+	delete_if $nt_client ipft_client0
+	delete_if $nt_router ipft_client_r0
+	delete_if $nt_router ipft_server_r0
+	delete_if $nt_server ipft_server0
+
+	delete_vnic ipft_client0 ipft_nic0 0 $nt_client
+	delete_vnic ipft_client_r0 ipft_nic1 0 $nt_router
+	delete_vnic ipft_server_r0 ipft_nic1 5 $nt_router
+	delete_vnic ipft_server0 ipft_nic1 5 $nt_server
+
+	delete_simnet ipft_nic0
+	delete_simnet ipft_nic1
+}
+
+function usage
+{
+	echo "$nt_tname -cflnpuv <client> <router> <server>" >&2
+}
+
+#
+# Set test defaults.
+#
+nt_tname=${NT_TNAME:-$(basename $0)}
+nt_ulp_full=0
+nt_ulp_partial=0
+nt_tcp_lso=0
+nt_udp=0
+nt_cleanup=1
+nt_cleanup_only=0
+
+nt_tdirprefix=/tmp/${nt_tname}
+nt_tdir=${nt_tdirprefix}.$$
+nt_dfile=${nt_tdir}/${nt_tname}.data
+nt_efile=${nt_tdir}/${nt_tname}-expected-sha1
+nt_rfile=${nt_tdir}/${nt_tname}-received-sha1
+nt_ofile=${nt_tdir}/${nt_tname}-received
+nt_client_subnet=192.168.77.0/24
+nt_client_ip=192.168.77.2
+nt_client_router_ip=192.168.77.1
+nt_server_subnet=192.168.88.0/24
+nt_server_ip=192.168.88.2
+nt_server_router_ip=192.168.88.1
+nt_port=7774
+nt_client_subnet6=fd00:0:1:4d::2/64
+nt_client_ip6=fd00:0:1:4d::2
+nt_client_router_ip6=fd00:0:1:4d::1
+nt_server_subnet6=fd00:0:1:58::/64
+nt_server_router_ip6=fd00:0:1:58::1
+nt_server_ip6=fd00:0:1:58::2
+nt_port6=7776
+
+while getopts "cflnpuv" opt; do
+	case $opt in
+	c)
+		nt_cleanup_only=1
+		;;
+	f)
+		nt_ulp_full=1
+		;;
+	l)
+		nt_tcp_lso=1
+		;;
+	n)
+		nt_cleanup=0
+		;;
+	p)
+		nt_ulp_partial=1
+		;;
+	u)
+		nt_udp=1
+		;;
+	v)
+		DEBUG=1
+		;;
+	esac
+done
+
+shift $((OPTIND - 1))
+
+if ((nt_ulp_partial == 1)) && ((nt_ulp_full == 1)); then
+	fail "both partial and full checksum enabled"
+fi
+
+if (( $# != 3 )); then
+	usage
+	fail "wrong number of arguments"
+fi
+
+nt_client=$1
+nt_router=$2
+nt_server=$3
+
+if [[ "$nt_client" == "$nt_router" || "$nt_router" == "$nt_server" ||
+	      "$nt_client" == "$nt_server" ]]; then
+	fail "all zones must be unique"
+fi
+
+dbg "client zone: $nt_client"
+dbg "router zone: $nt_router"
+dbg "server zone: $nt_server"
+
+BAIL=1
+zone_exists $nt_client || fail "zone $nt_client not found"
+zone_exists $nt_router || fail "zone $nt_router not found"
+zone_exists $nt_server || fail "zone $nt_server not found"
+
+zone_running $nt_client
+zone_running $nt_router
+zone_running $nt_server
+
+if ! zlogin $nt_client ls /usr/bin/socat > /dev/null; then
+	fail "zone $nt_client missing socat"
+fi
+
+if ! zlogin $nt_server ls /usr/bin/socat > /dev/null; then
+	fail "zone $nt_client missing socat"
+fi
+
+#
+# Make a best effort to cleanup artifacts from a previous run.
+#
+if ((nt_cleanup_only == 1)); then
+	dbg "performing cleanup only"
+	BAIL=0
+	cleanup
+	BAIL=1
+	exit 0
+fi
+
+mkdir $nt_tdir
+zlogin $nt_client mkdir $nt_tdir
+zlogin $nt_server mkdir $nt_tdir
+
+create_simnet ipft_nic0
+create_simnet ipft_nic1
+link_simnets ipft_nic0 ipft_nic1
+
+if ((nt_ulp_partial == 1)); then
+	set_linkprop ipft_nic0 _tx_ulp_cksum partial
+	set_linkprop ipft_nic1 _tx_ulp_cksum partial
+fi
+
+if ((nt_ulp_full == 1)); then
+	set_linkprop ipft_nic0 _tx_ulp_cksum fullv4
+	set_linkprop ipft_nic1 _tx_ulp_cksum fullv4
+fi
+
+if ((nt_ulp_full == 1)) || ((nt_ulp_partial == 1)); then
+	set_linkprop ipft_nic0 _tx_ipv4_cksum on
+	set_linkprop ipft_nic1 _tx_ipv4_cksum on
+fi
+
+if ((nt_tcp_lso == 1)); then
+	set_linkprop ipft_nic0 _lso on
+	set_linkprop ipft_nic1 _lso on
+fi
+
+create_vnic ipft_client0 ipft_nic0 0 $nt_client
+create_vnic ipft_client_r0 ipft_nic1 0 $nt_router
+create_vnic ipft_server_r0 ipft_nic1 5 $nt_router
+create_vnic ipft_server0 ipft_nic1 5 $nt_server
+
+ip_fwd_enable $nt_router
+
+create_addr $nt_client ipft_client0 $nt_client_ip/24
+create_addr $nt_router ipft_client_r0 $nt_client_router_ip/24
+create_addr $nt_router ipft_server_r0 $nt_server_router_ip/24
+create_addr $nt_server ipft_server0 $nt_server_ip/24
+
+add_route $nt_client $nt_server_ip $nt_server_subnet $nt_client_router_ip
+add_route $nt_server $nt_client_ip $nt_client_subnet $nt_server_router_ip
+
+create_addr6 $nt_client ipft_client0 $nt_client_ip6
+create_addr6 $nt_router ipft_client_r0 $nt_client_router_ip6
+create_addr6 $nt_router ipft_server_r0 $nt_server_router_ip6
+create_addr6 $nt_server ipft_server0 $nt_server_ip6
+
+add_route6 $nt_client $nt_server_ip6 $nt_server_subnet6 $nt_client_router_ip6
+add_route6 $nt_server $nt_client_ip6 $nt_client_subnet6 $nt_server_router_ip6
+
+dd if=/dev/urandom of=$nt_dfile bs=1024 count=1024 > /dev/null 2>&1
+if (($? != 0)); then
+	fail "failed to create data file: $nt_dfile"
+else
+	dbg "created data file: $nt_dfile"
+fi
+
+digest -a sha1 $nt_dfile > $nt_efile
+
+# ================================================================
+# client -> server
+# ================================================================
+ping $nt_client $nt_client_ip $nt_server_ip
+ping $nt_client $nt_client_ip6 $nt_server_ip6
+
+start_server $nt_server TCP4 $nt_server_ip $nt_port $nt_ofile
+nt_listener_ppid=$!
+
+# Give the server time to start.
+sleep 1
+
+dbg "sending 1M $nt_client ($nt_client_ip) -> $nt_server ($nt_server_ip)"
+zlogin $nt_client /usr/bin/socat -b 8192 STDIN \
+       TCP4:$nt_server_ip:$nt_port,connect-timeout=5 < $nt_dfile
+
+if (($? != 0)); then
+	pkill -TERM -P $nt_listener_ppid
+	fail "failed to run socat client"
+else
+	dbg "sent 1M $nt_client ($nt_client_ip) -> $nt_server ($nt_server_ip)"
+fi
+
+#
+# The client may have exited but make sure to give the server time to
+# exit and finish computing the SHA1.
+#
+dbg "waiting for listener $nt_listener_ppid"
+wait_for_pid $nt_listener_ppid 5
+dbg "listener $nt_listener_ppid exited"
+
+digest -a sha1 /zones/$nt_server/root/$nt_ofile > $nt_rfile
+
+if ! diff $nt_efile $nt_rfile; then
+	fail "SHA1 comparison failed"
+else
+	dbg "SHA1 comparison passed"
+fi
+
+start_server $nt_server TCP6 $nt_server_ip6 $nt_port6 $nt_rfile
+listener_ppid=$!
+
+# Give the server time to start.
+sleep 1
+
+zlogin $nt_client /usr/bin/socat -b 8192 STDIN \
+       TCP6:[${nt_server_ip6}]:$nt_port6,connect-timeout=5 < $nt_dfile
+
+if (($? != 0)); then
+	pkill -TERM -P $nt_listener_ppid
+	fail "failed to run socat client IPv6"
+else
+	dbg "sent 1M $nt_client ($nt_client_ip6)" \
+	    "-> $nt_server ($nt_server_ip6) IPv6"
+fi
+
+#
+# The client may have exited but make sure to give the server time to
+# exit and finish computing the SHA1.
+#
+dbg "waiting for listener $nt_listener_ppid"
+wait_for_pid $nt_listener_ppid 5
+dbg "listener $nt_listener_ppid exited"
+
+digest -a sha1 /zones/$nt_server/root/$nt_ofile > $nt_rfile
+
+if ! diff $nt_efile $nt_rfile; then
+	fail "SHA1 comparison failed"
+else
+	dbg "SHA1 comparison passed"
+fi
+
+if ((nt_udp == 1)); then
+	ping_udp $nt_client $nt_client_ip $nt_server_ip 256 3
+	ping_udp $nt_client $nt_client_ip6 $nt_server_ip6 256 3
+
+	#
+	# Test IP fragmentation by sending a larger-than-MTU datagram.
+	# You can verify fragmentation is happening by dtracing the
+	# various "Frag" and "Reasm" mibs.
+	#
+	dbg "test IP fragmentation $nt_client_ip -> $nt_server_ip"
+	ping_udp $nt_client $nt_client_ip $nt_server_ip $((1024 * 16)) 3
+
+	dbg "test IPv6 fragmentation $nt_client_ip6 -> $nt_server_ip6"
+	ping_udp $nt_client $nt_client_ip6 $nt_server_ip6 $((1024 * 16)) 3
+fi
+
+# ================================================================
+# server -> client
+# ================================================================
+ping $nt_server $nt_server_ip $nt_client_ip
+ping $nt_server $nt_server_ip6 $nt_client_ip6
+
+start_server $nt_client TCP4 $nt_client_ip $nt_port $nt_ofile
+nt_listener_ppid=$!
+
+# Give the listener time to start.
+sleep 1
+
+zlogin $nt_server /usr/bin/socat -b 8192 STDIN \
+       TCP4:$nt_client_ip:$nt_port,bind=$nt_server_ip,connect-timeout=5 \
+       < $nt_dfile
+
+if (($? != 0)); then
+	pkill -TERM -P $nt_listener_ppid
+	fail "failed to run socat client"
+else
+	dbg "sent 1M $nt_server ($nt_server_ip) -> $nt_client ($nt_client_ip)"
+fi
+
+#
+# The client may have exited but make sure to give the server time to
+# exit and finish computing the SHA1.
+#
+dbg "waiting for listener $nt_listener_ppid"
+wait_for_pid $nt_listener_ppid 5
+dbg "listener $nt_listener_ppid exited"
+
+digest -a sha1 /zones/$nt_client/root/$nt_ofile > $nt_rfile
+
+if ! diff $nt_efile $nt_rfile; then
+	fail "SHA1 comparison failed"
+else
+	dbg "SHA1 comparison passed"
+fi
+
+start_server $nt_client TCP6 $nt_client_ip6 $nt_port6 $nt_ofile
+nt_listener_ppid=$!
+
+# Give the listener time to start.
+sleep 1
+
+zlogin $nt_server /usr/bin/socat -b 8192 STDIN \
+       TCP6:[$nt_client_ip6]:$nt_port6,connect-timeout=5 < $nt_dfile
+
+if (($? != 0)); then
+	pkill -TERM -P $nt_listener_ppid
+	fail "failed to run socat client IPv6"
+else
+	dbg "sent 1M $nt_server ($nt_server_ip6) -> $nt_client ($nt_client_ip6)"
+fi
+
+#
+# The client may have exited but make sure to give the server time to
+# exit and finish computing the SHA1.
+#
+dbg "waiting for listener $nt_listener_ppid"
+wait_for_pid $nt_listener_ppid 5
+dbg "server $nt_listener_ppid exited"
+
+digest -a sha1 /zones/$nt_client/root/$nt_ofile > $nt_rfile
+
+if ! diff $nt_efile $nt_rfile; then
+	fail "SHA1 comparison failed"
+else
+	dbg "SHA1 comparison passed"
+fi
+
+if ((nt_udp == 1)); then
+	ping_udp $nt_server $nt_server_ip $nt_client_ip 256 3
+	ping_udp $nt_server $nt_server_ip6 $nt_client_ip6 256 3
+
+	#
+	# Test IP fragmentation by sending a larger-than-MTU datagram.
+	# You can verify fragmentation is happening by dtracing the
+	# various "Frag" and "Reasm" mibs.
+	#
+	dbg "test IP fragmentation $nt_server_ip -> $nt_client_ip"
+	ping_udp $nt_server $nt_server_ip $nt_client_ip $((1024 * 16)) 3
+
+	dbg "test IPv6 fragmentation $nt_server_ip6 -> $nt_client_ip6"
+	ping_udp $nt_server $nt_server_ip6 $nt_client_ip6 $((1024 * 16)) 3
+fi
+
+if ((nt_cleanup == 0)); then
+	dbg "skipping cleanup"
+	echo "PASS [$nt_tname]"
+	exit 0
+fi
+
+cleanup
+echo "PASS [$nt_tname]"
diff --git a/usr/src/test/net-tests/tests/forwarding/ip_fwd_full_cksum.ksh b/usr/src/test/net-tests/tests/forwarding/ip_fwd_full_cksum.ksh
new file mode 100644
index 0000000000..57c9e2d271
--- /dev/null
+++ b/usr/src/test/net-tests/tests/forwarding/ip_fwd_full_cksum.ksh
@@ -0,0 +1,38 @@
+#!/usr/bin/ksh
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+
+#
+# Copyright 2019 Joyent, Inc.
+#
+
+if [[ -z $NET_TESTS ]]; then
+	echo "NET_TESTS not set" >&2
+	exit 1
+fi
+
+. $NET_TESTS/tests/net_common
+. $NET_TESTS/config/ip_forwarding.config
+
+if [[ -z "$NT_CLIENT" ]]; then
+	fail "NT_CLIENT must be set"
+fi
+
+if [[ -z "$NT_ROUTER" ]]; then
+	fail "NT_ROUTER must be set"
+fi
+
+if [[ -z "$NT_SERVER" ]]; then
+	fail "NT_SERVER must be set"
+fi
+
+export NT_TNAME=$(basename $0)
+$NET_TESTS/tests/forwarding/ip_forwarding -fuv $NT_CLIENT $NT_ROUTER $NT_SERVER
+exit $?
diff --git a/usr/src/test/net-tests/tests/forwarding/ip_fwd_full_cksum_lso.ksh b/usr/src/test/net-tests/tests/forwarding/ip_fwd_full_cksum_lso.ksh
new file mode 100644
index 0000000000..a9b6f98a46
--- /dev/null
+++ b/usr/src/test/net-tests/tests/forwarding/ip_fwd_full_cksum_lso.ksh
@@ -0,0 +1,38 @@
+#!/usr/bin/ksh
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+
+#
+# Copyright 2019 Joyent, Inc.
+#
+
+if [[ -z $NET_TESTS ]]; then
+	echo "NET_TESTS not set" >&2
+	exit 1
+fi
+
+. $NET_TESTS/tests/net_common
+. $NET_TESTS/config/ip_forwarding.config
+
+if [[ -z "$NT_CLIENT" ]]; then
+	fail "NT_CLIENT must be set"
+fi
+
+if [[ -z "$NT_ROUTER" ]]; then
+	fail "NT_ROUTER must be set"
+fi
+
+if [[ -z "$NT_SERVER" ]]; then
+	fail "NT_SERVER must be set"
+fi
+
+export NT_TNAME=$(basename $0)
+$NET_TESTS/tests/forwarding/ip_forwarding -fluv $NT_CLIENT $NT_ROUTER $NT_SERVER
+exit $?
diff --git a/usr/src/test/net-tests/tests/forwarding/ip_fwd_no_cksum.ksh b/usr/src/test/net-tests/tests/forwarding/ip_fwd_no_cksum.ksh
new file mode 100644
index 0000000000..ad593568d0
--- /dev/null
+++ b/usr/src/test/net-tests/tests/forwarding/ip_fwd_no_cksum.ksh
@@ -0,0 +1,38 @@
+#!/usr/bin/ksh
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+
+#
+# Copyright 2019 Joyent, Inc.
+#
+
+if [[ -z $NET_TESTS ]]; then
+	echo "NET_TESTS not set" >&2
+	exit 1
+fi
+
+. $NET_TESTS/tests/net_common
+. $NET_TESTS/config/ip_forwarding.config
+
+if [[ -z "$NT_CLIENT" ]]; then
+	fail "NT_CLIENT must be set"
+fi
+
+if [[ -z "$NT_ROUTER" ]]; then
+	fail "NT_ROUTER must be set"
+fi
+
+if [[ -z "$NT_SERVER" ]]; then
+	fail "NT_SERVER must be set"
+fi
+
+export NT_TNAME=$(basename $0)
+$NET_TESTS/tests/forwarding/ip_forwarding -uv $NT_CLIENT $NT_ROUTER $NT_SERVER
+exit $?
diff --git a/usr/src/test/net-tests/tests/forwarding/ip_fwd_partial_cksum.ksh b/usr/src/test/net-tests/tests/forwarding/ip_fwd_partial_cksum.ksh
new file mode 100644
index 0000000000..b7d51ab224
--- /dev/null
+++ b/usr/src/test/net-tests/tests/forwarding/ip_fwd_partial_cksum.ksh
@@ -0,0 +1,38 @@
+#!/usr/bin/ksh
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+
+#
+# Copyright 2019 Joyent, Inc.
+#
+
+if [[ -z $NET_TESTS ]]; then
+	echo "NET_TESTS not set" >&2
+	exit 1
+fi
+
+. $NET_TESTS/tests/net_common
+. $NET_TESTS/config/ip_forwarding.config
+
+if [[ -z "$NT_CLIENT" ]]; then
+	fail "NT_CLIENT must be set"
+fi
+
+if [[ -z "$NT_ROUTER" ]]; then
+	fail "NT_ROUTER must be set"
+fi
+
+if [[ -z "$NT_SERVER" ]]; then
+	fail "NT_SERVER must be set"
+fi
+
+export NT_TNAME=$(basename $0)
+$NET_TESTS/tests/forwarding/ip_forwarding -puv $NT_CLIENT $NT_ROUTER $NT_SERVER
+exit $?
diff --git a/usr/src/test/net-tests/tests/forwarding/ip_fwd_partial_cksum_lso.ksh b/usr/src/test/net-tests/tests/forwarding/ip_fwd_partial_cksum_lso.ksh
new file mode 100644
index 0000000000..426c6d3614
--- /dev/null
+++ b/usr/src/test/net-tests/tests/forwarding/ip_fwd_partial_cksum_lso.ksh
@@ -0,0 +1,38 @@
+#!/usr/bin/ksh
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+
+#
+# Copyright 2019 Joyent, Inc.
+#
+
+if [[ -z $NET_TESTS ]]; then
+	echo "NET_TESTS not set" >&2
+	exit 1
+fi
+
+. $NET_TESTS/tests/net_common
+. $NET_TESTS/config/ip_forwarding.config
+
+if [[ -z "$NT_CLIENT" ]]; then
+	fail "NT_CLIENT must be set"
+fi
+
+if [[ -z "$NT_ROUTER" ]]; then
+	fail "NT_ROUTER must be set"
+fi
+
+if [[ -z "$NT_SERVER" ]]; then
+	fail "NT_SERVER must be set"
+fi
+
+export NT_TNAME=$(basename $0)
+$NET_TESTS/tests/forwarding/ip_forwarding -pluv $NT_CLIENT $NT_ROUTER $NT_SERVER
+exit $?
diff --git a/usr/src/test/net-tests/tests/net_common.ksh b/usr/src/test/net-tests/tests/net_common.ksh
new file mode 100644
index 0000000000..8465ead088
--- /dev/null
+++ b/usr/src/test/net-tests/tests/net_common.ksh
@@ -0,0 +1,631 @@
+#!/usr/bin/ksh
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+
+#
+# Copyright 2019 Joyent, Inc.
+#
+
+#
+# Functions shared across the network tests.
+#
+
+DEBUG=0
+
+function dbg
+{
+	typeset msg="$*"
+	if (($DEBUG == 1)); then
+		echo "DBG [$nt_tname]: $msg"
+	fi
+}
+
+function fail
+{
+	typeset msg="$*"
+	echo "FAIL [$nt_tname]: $msg" >&2
+	exit 1
+}
+
+function maybe_fail
+{
+	typeset msg=$1
+
+	if ((BAIL == 1)); then
+		fail "$msg"
+	else
+		dbg "$msg"
+		return 1
+	fi
+}
+
+function zone_exists
+{
+	typeset name=$1
+
+	if (($# != 1)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	dbg "checking for existence of zone: $name"
+	if zoneadm -z $name list > /dev/null 2>&1; then
+		dbg "found zone: $name"
+		return 0
+	else
+		dbg "zone not found: $name"
+		return 1
+	fi
+}
+
+function zone_running
+{
+	typeset name=$1
+	typeset state=$(zoneadm -z $name list -p | awk -F: '{ print $3 }')
+	typeset err="zone $name is not running"
+
+	if (($# != 1)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	dbg "check if zone $name is running"
+	dbg "state of zone $name: $state"
+	if [[ "$state" == "running" ]]; then
+		dbg "zone $name is running"
+		return 0
+	fi
+
+	maybe_fail "$err"
+}
+
+function simnet_exists
+{
+	typeset name=$1
+
+	if (($# != 1)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	if dladm show-simnet $name > /dev/null 2>&1; then
+		dbg "simnet $name found"
+		return 0
+	else
+		dbg "simnet $name not found"
+		return 1
+	fi
+}
+
+function create_simnet
+{
+	typeset name=$1
+	typeset err="failed to create simnet $name"
+
+	if (($# != 1)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	dbg "creating simnet $name"
+	if simnet_exists $name; then
+		dbg "simnet $name already exists"
+		maybe_fail "$err"
+		return 1
+	fi
+
+	if dladm create-simnet > /dev/null $name; then
+		dbg "created simnet $name"
+		return 0
+	fi
+
+	maybe_fail "$err"
+}
+
+function delete_simnet
+{
+	typeset name=$1
+	typeset err="failed to delete simnet $name"
+
+	if (($# != 1)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	dbg "deleting simnet $name"
+	if ! simnet_exists $name; then
+		dbg "simnet $name doesn't exist"
+		return 1
+	fi
+
+	if dladm delete-simnet $name; then
+		dbg "simnet $name deleted"
+		return 0
+	fi
+
+	maybe_fail "$err"
+}
+
+function link_simnets
+{
+	typeset sim1=$1
+	typeset sim2=$2
+	typeset err="failed to link simnet $sim1 to $sim2"
+
+	if (($# != 2)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	dbg "linking simnet $sim1 to $sim2"
+	if dladm modify-simnet -p $sim2 $sim1 > /dev/null; then
+		dbg "linked simnet $sim1 to $sim2"
+		return 0
+	fi
+
+	maybe_fail "$err"
+}
+
+function vnic_exists
+{
+	typeset name=$1
+	typeset vid=$2
+	typeset over=$3
+	typeset zone=$4
+
+	if (($# != 4)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	if dladm show-vnic -z $zone $name > /dev/null 2>&1; then
+		typeset avid=$(dladm show-vnic -z $zone -p -o vid $name)
+		typeset aover=$(dladm show-vnic -z $zone -p -o over $name)
+		if (($avid == $vid)) && [ $aover == $over ]; then
+			return 0
+		else
+			return 1
+		fi
+	else
+		return 1
+	fi
+}
+
+function create_vnic
+{
+	typeset name=$1
+	typeset over=$2
+	typeset vid=$3
+	typeset zone=$4
+	typeset r=1
+	typeset vid_opt=""
+	typeset vnic_info="$name, vid: $vid, over: $over, zone: $zone"
+	typeset err="failed to create VNIC: $vnic_info"
+
+	if (($# != 4)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	if ((vid != 0)); then
+		vid_opt="-v $vid"
+	fi
+
+	dbg "creating VNIC: $vnic_info"
+	if dladm create-vnic -t -p zone=$zone -l $over \
+		 $vid_opt $name > /dev/null 2>&1
+	then
+		dbg "created VNIC: $vnic_info"
+		return 0
+	fi
+
+	maybe_fail "$err"
+}
+
+function delete_vnic
+{
+	typeset name=$1
+	typeset over=$2
+	typeset vid=$3
+	typeset zone=$4
+	typeset vnic_info="$name, vid: $vid, over: $over, zone: $zone"
+	typeset err1="failed to assign VNIC $name from $zone to GZ"
+	typeset err2="failed to delete VNIC: $vnic_info"
+
+	if (($# != 4)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	if ! vnic_exists $name $vid $over $zone; then
+		dbg "VNIC doesn't exist: $vnic_info"
+		return 0
+	fi
+
+	dbg "assigning VNIC $name from $zone to GZ"
+	if ! dladm set-linkprop -t -z $zone -p zone=global $name; then
+		maybe_fail "$err1"
+		return 1
+	fi
+
+	dbg "deleting VNIC: $vnic_info"
+	if dladm delete-vnic $name > /dev/null; then
+		dbg "deleted VNIC: $vnic_info"
+		return 0
+	fi
+
+	maybe_fail "$err2"
+}
+
+function create_addr
+{
+	typeset zone=$1
+	typeset vnic=$2
+	typeset ip=$3
+	typeset ipname=${vnic}/v4
+
+	if (($# != 3)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	if zlogin $zone ipadm create-addr -t -T static -a $ip \
+		  $ipname > /dev/null
+	then
+		dbg "created addr $ipname ($ip) in zone $zone"
+		return 0
+	fi
+
+	maybe_fail "failed to create addr $ipname ($ip) in zone $zone"
+}
+
+function create_addr6
+{
+	typeset zone=$1
+	typeset vnic=$2
+	typeset ip=$3
+	typeset ll_name=${vnic}/v6
+	typeset uni_name=${vnic}/v6add
+	typeset err1="failed to create link-local addr $ll_name in zone $zone"
+	typeset err2="failed to create unicast addr $uni_name in zone $zone"
+
+	if (($# != 3)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	if zlogin $zone ipadm create-addr -t -T addrconf $ll_name; then
+		dbg "created link-local addr $ll_name in zone $zone"
+	else
+		maybe_fail "$err1"
+		return 1
+	fi
+
+	if zlogin $zone ipadm create-addr -t -T static -a $ip/64 $uni_name; then
+		dbg "created unicast addr $uni_name in zone $zone"
+	else
+		maybe_fail "$err2"
+	fi
+}
+
+function delete_addr
+{
+	typeset zone=$1
+	typeset ifname=$2
+	typeset version=$3
+	typeset ipname=$ifname/$version
+
+	if (($# != 3)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	if zlogin $zone ipadm show-addr $ipname > /dev/null 2>&1; then
+		if zlogin $zone ipadm delete-addr $ipname > /dev/null; then
+			dbg "deleted addr $ipname in zone $zone"
+		else
+			maybe_fail "failed to delete addr $ipname in zone $zone"
+			return 1
+		fi
+	else
+		dbg "addr $ipname doesn't exist in zone $zone"
+	fi
+
+	if [[ "v6" == "$version" ]]; then
+		typeset ipname=$ifname/v6add
+		typeset err="failed to delete addr $ipname in zone $zone"
+
+		if zlogin $zone ipadm show-addr $ipname > /dev/null 2>&1; then
+			if zlogin $zone ipadm delete-addr $ipname > /dev/null
+			then
+				dbg "deleted addr $ipname in zone $zone"
+			else
+				maybe_fail "$err"
+			fi
+		else
+			dbg "addr $ipname doesn't exist in zone $zone"
+		fi
+	fi
+}
+
+function delete_if
+{
+	typeset zone=$1
+	typeset ifname=$2
+	typeset err="failed to delete interface $ifname in zone $zone"
+
+	if (($# != 2)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	if zlogin $zone ipadm show-if $ifname > /dev/null 2>&1; then
+		if zlogin $zone ipadm delete-if $ifname > /dev/null; then
+			dbg "deleted interface $ifname in zone $zone"
+		else
+			maybe_fail "$err"
+		fi
+	else
+		dbg "interface $ifname doesn't exist in zone $zone"
+	fi
+}
+
+function ip_fwd_enable
+{
+	typeset zone=$1
+
+	if (($# != 1)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	if zlogin $zone routeadm -p ipv4-forwarding | \
+			egrep 'current=enabled' > /dev/null
+	then
+		dbg "IPv4 forwarding already enabled for $zone"
+	else
+		if zlogin $zone routeadm -ue ipv4-forwarding; then
+			dbg "enabled IPv4 forwarding for $zone"
+		else
+			maybe_fail "failed to enable IPv4 forwarding for $zone"
+			return 1
+		fi
+	fi
+
+	if zlogin $zone routeadm -p ipv6-forwarding | \
+			egrep 'current=enabled' > /dev/null
+	then
+		dbg "IPv6 forwarding already enabled for $zone"
+	else
+		if zlogin $zone routeadm -ue ipv6-forwarding; then
+			dbg "enabled IPv6 forwarding for $zone"
+		else
+			maybe_fail "failed to enable IPv6 forwarding for $zone"
+		fi
+	fi
+}
+
+function ip_fwd_disable
+{
+	typeset zone=$1
+
+	if (($# != 1)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	if zlogin $zone routeadm -p ipv4-forwarding | \
+			egrep 'current=disabled' > /dev/null
+	then
+		dbg "IPv4 forwarding already disabled for $zone"
+	else
+		if zlogin $zone routeadm -ud ipv4-forwarding; then
+			dbg "disabled IPv4 forwarding in $zone"
+		else
+			maybe_fail "failed to disable IPv4 forwarding in $zone"
+			return 1
+		fi
+	fi
+
+	if zlogin $zone routeadm -p ipv6-forwarding | \
+			egrep 'current=disabled' > /dev/null
+	then
+		dbg "IPv6 forwarding already disabled for $zone"
+	else
+		if zlogin $zone routeadm -ud ipv6-forwarding; then
+			dbg "disabled IPv6 forwarding in $zone"
+		else
+			maybe_fail "failed to disable IPv6 forwarding in $zone"
+		fi
+	fi
+}
+
+function add_route
+{
+	typeset zone=$1
+	typeset dest=$2
+	typeset net=$3
+	typeset gateway=$4
+
+	if (($# != 4)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	if zlogin $zone route -n add $net $gateway > /dev/null; then
+		dbg "added route $gateway => $net to $zone"
+		return 0
+	fi
+
+	maybe_fail "failed to add route $gateway => $net to $zone"
+}
+
+function add_route6
+{
+	typeset zone=$1
+	typeset dest=$2
+	typeset net=$3
+	typeset gateway=$4
+
+	if (($# != 4)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	if zlogin $zone route -n add -inet6 $net $gateway > /dev/null
+	then
+		dbg "added route $gateway => $net to $zone"
+		return 0
+	fi
+
+	maybe_fail "failed to add route $gateway => $net to $zone"
+}
+
+function rm_route
+{
+	typeset zone=$1
+	typeset dest=$2
+	typeset net=$3
+	typeset gateway=$4
+	typeset gw=$(zlogin $zone route -n get $dest | \
+			     grep gateway | awk '{ print $2 }')
+	typeset err="failed to remove route $gateway => $net from $zone"
+
+	if (($# != 4)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	if [[ "$gw" == "$gateway" ]]; then
+		if zlogin $zone route -n delete $net $gateway > /dev/null
+		then
+			dbg "removed route $gateway => $net from $zone"
+		else
+			maybe_fail "$err"
+		fi
+	else
+		dbg "$zone already lacked route $gateway => $net"
+	fi
+}
+
+function rm_route6
+{
+	typeset zone=$1
+	typeset dest=$2
+	typeset net=$3
+	typeset gateway=$4
+	typeset gw=$(zlogin $zone route -n get -inet6 $dest | \
+			     grep gateway | awk '{ print $2 }')
+	typeset err="failed to remove route $gateway => $net from $zone"
+
+	if (($# != 4)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	if [[ "$gw" == "$gateway" ]]; then
+		if zlogin $zone route -n delete -inet6 $net $gateway > /dev/null
+		then
+			dbg "removed route $gateway => $net from $zone"
+		else
+			maybe_fail "$err"
+		fi
+	else
+		dbg "$zone already lacked route $gateway => $net"
+	fi
+}
+
+function set_linkprop
+{
+	typeset link=$1
+	typeset prop=$2
+	typeset val=$3
+	typeset err="failed to set $link prop: $prop=$val"
+
+	if (($# != 3)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	dbg "attempt to set $link prop: $prop=$val"
+	if dladm set-linkprop -p $prop=$val $link; then
+		dbg "set $link prop: $prop=$val"
+		return 0
+	fi
+
+	maybe_fail "$err"
+}
+
+function ping
+{
+	typeset zone=$1
+	typeset src=$2
+	typeset dst=$3
+	typeset info="$src -> $dst"
+
+	if (($# != 3)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	dbg "ping: $info"
+	if zlogin $zone ping $dst > /dev/null 2>&1; then
+		dbg "successful ping: $info"
+		return 0
+	fi
+
+	maybe_fail "could not ping: $info"
+}
+
+function ping_udp
+{
+	typeset client=$1
+	typeset client_ip=$2
+	typeset server_ip=$3
+	typeset size=$4
+	typeset num=$5
+	typeset info="$client_ip -> $server_ip (size: $size)"
+
+	if (($# != 5)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	dbg "UDP ping: $info"
+	if zlogin $client ping -ns -U $server_ip $size $num > /dev/null; then
+		dbg "UDP ping passed: $info"
+		return 0
+	fi
+
+	maybe_fail "UDP ping failed: $info"
+}
+
+function start_server
+{
+	typeset zone=$1
+	typeset type=$2
+	typeset ip=$3
+	typeset port=$4
+	typeset ofile=$5
+
+	if (($# != 5)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	dbg "start server $rfile"
+	zlogin $zone \
+	       /usr/bin/socat -u ${type}-LISTEN:$port,bind=[$ip],reuseaddr \
+	       CREATE:$ofile &
+	listener_ppid=$!
+	dbg "listener PPID: $listener_ppid, zone $zone"
+}
+
+function wait_for_pid
+{
+	typeset pid=$1
+	typeset seconds=$2
+	typeset s=0
+
+	if (($# != 2)); then
+		fail "$0: incorrect number of args provided"
+	fi
+
+	while true; do
+		if kill -0 $pid > /dev/null 2>&1; then
+			if ((seconds == s)); then
+				maybe_fail "timed out waiting for pid $pid"
+				return 1
+			fi
+			dbg "waiting for pid $pid"
+			sleep 1
+			((s++))
+		else
+			return 0
+		fi
+	done
+}
diff --git a/usr/src/uts/common/inet/ip/ip6.c b/usr/src/uts/common/inet/ip/ip6.c
index 9c7f6b4000..afaf01024f 100644
--- a/usr/src/uts/common/inet/ip/ip6.c
+++ b/usr/src/uts/common/inet/ip/ip6.c
@@ -22,6 +22,7 @@
  * Copyright (c) 1991, 2010, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 1990 Mentat Inc.
  * Copyright 2017 OmniTI Computer Consulting, Inc. All rights reserved.
+ * Copyright 2019 Joyent, Inc.
  */
 
 #include <sys/types.h>
@@ -2730,108 +2731,15 @@ done:
 }
 
 /*
- * Try to determine where and what are the IPv6 header length and
- * pointer to nexthdr value for the upper layer protocol (or an
- * unknown next hdr).
- *
- * Parameters returns a pointer to the nexthdr value;
- * Must handle malformed packets of various sorts.
- * Function returns failure for malformed cases.
- */
-boolean_t
-ip_hdr_length_nexthdr_v6(mblk_t *mp, ip6_t *ip6h, uint16_t *hdr_length_ptr,
-    uint8_t **nexthdrpp)
-{
-	uint16_t length;
-	uint_t	ehdrlen;
-	uint8_t	*nexthdrp;
-	uint8_t *whereptr;
-	uint8_t *endptr;
-	ip6_dest_t *desthdr;
-	ip6_rthdr_t *rthdr;
-	ip6_frag_t *fraghdr;
-
-	ASSERT(IPH_HDR_VERSION(ip6h) == IPV6_VERSION);
-	length = IPV6_HDR_LEN;
-	whereptr = ((uint8_t *)&ip6h[1]); /* point to next hdr */
-	endptr = mp->b_wptr;
-
-	nexthdrp = &ip6h->ip6_nxt;
-	while (whereptr < endptr) {
-		/* Is there enough left for len + nexthdr? */
-		if (whereptr + MIN_EHDR_LEN > endptr)
-			break;
-
-		switch (*nexthdrp) {
-		case IPPROTO_HOPOPTS:
-		case IPPROTO_DSTOPTS:
-			/* Assumes the headers are identical for hbh and dst */
-			desthdr = (ip6_dest_t *)whereptr;
-			ehdrlen = 8 * (desthdr->ip6d_len + 1);
-			if ((uchar_t *)desthdr +  ehdrlen > endptr)
-				return (B_FALSE);
-			nexthdrp = &desthdr->ip6d_nxt;
-			break;
-		case IPPROTO_ROUTING:
-			rthdr = (ip6_rthdr_t *)whereptr;
-			ehdrlen =  8 * (rthdr->ip6r_len + 1);
-			if ((uchar_t *)rthdr +  ehdrlen > endptr)
-				return (B_FALSE);
-			nexthdrp = &rthdr->ip6r_nxt;
-			break;
-		case IPPROTO_FRAGMENT:
-			fraghdr = (ip6_frag_t *)whereptr;
-			ehdrlen = sizeof (ip6_frag_t);
-			if ((uchar_t *)&fraghdr[1] > endptr)
-				return (B_FALSE);
-			nexthdrp = &fraghdr->ip6f_nxt;
-			break;
-		case IPPROTO_NONE:
-			/* No next header means we're finished */
-		default:
-			*hdr_length_ptr = length;
-			*nexthdrpp = nexthdrp;
-			return (B_TRUE);
-		}
-		length += ehdrlen;
-		whereptr += ehdrlen;
-		*hdr_length_ptr = length;
-		*nexthdrpp = nexthdrp;
-	}
-	switch (*nexthdrp) {
-	case IPPROTO_HOPOPTS:
-	case IPPROTO_DSTOPTS:
-	case IPPROTO_ROUTING:
-	case IPPROTO_FRAGMENT:
-		/*
-		 * If any know extension headers are still to be processed,
-		 * the packet's malformed (or at least all the IP header(s) are
-		 * not in the same mblk - and that should never happen.
-		 */
-		return (B_FALSE);
-
-	default:
-		/*
-		 * If we get here, we know that all of the IP headers were in
-		 * the same mblk, even if the ULP header is in the next mblk.
-		 */
-		*hdr_length_ptr = length;
-		*nexthdrpp = nexthdrp;
-		return (B_TRUE);
-	}
-}
-
-/*
  * Return the length of the IPv6 related headers (including extension headers)
  * Returns a length even if the packet is malformed.
  */
-int
+uint16_t
 ip_hdr_length_v6(mblk_t *mp, ip6_t *ip6h)
 {
 	uint16_t hdr_len;
-	uint8_t	*nexthdrp;
 
-	(void) ip_hdr_length_nexthdr_v6(mp, ip6h, &hdr_len, &nexthdrp);
+	(void) ip_hdr_length_nexthdr_v6(mp, ip6h, &hdr_len, NULL);
 	return (hdr_len);
 }
 
diff --git a/usr/src/uts/common/inet/ip/ip6_input.c b/usr/src/uts/common/inet/ip/ip6_input.c
index 96cc281da5..284eab8a70 100644
--- a/usr/src/uts/common/inet/ip/ip6_input.c
+++ b/usr/src/uts/common/inet/ip/ip6_input.c
@@ -977,9 +977,6 @@ ire_recv_forward_v6(ire_t *ire, mblk_t *mp, void *iph_arg, ip_recv_attr_t *ira)
 		ira->ira_pktlen = ntohs(ip6h->ip6_plen) + IPV6_HDR_LEN;
 	}
 
-	/* Packet is being forwarded. Turning off hwcksum flag. */
-	DB_CKSUMFLAGS(mp) = 0;
-
 	/*
 	 * Per RFC 3513 section 2.5.2, we must not forward packets with
 	 * an unspecified source address.
@@ -1101,7 +1098,14 @@ ip_forward_xmit_v6(nce_t *nce, mblk_t *mp, ip6_t *ip6h, ip_recv_attr_t *ira,
 
 	BUMP_MIB(dst_ill->ill_ip_mib, ipIfStatsHCOutForwDatagrams);
 
-	if (pkt_len > mtu) {
+	/*
+	 * If the packet arrived via MAC-loopback then it might be an
+	 * LSO packet; in this case the MAC layer will take care to
+	 * segment it. Otherwise, we have a normal packet that is
+	 * being forwarded from a source interface with an MTU larger
+	 * than the destination's; in this case IP must fragment it.
+	 */
+	if (pkt_len > mtu && (DB_CKSUMFLAGS(mp) & HW_LSO) == 0) {
 		BUMP_MIB(dst_ill->ill_ip_mib, ipIfStatsOutFragFails);
 		ip_drop_output("ipIfStatsOutFragFails", mp, dst_ill);
 		if (iraflags & IRAF_SYSTEM_LABELED) {
diff --git a/usr/src/uts/common/inet/ip/ip_input.c b/usr/src/uts/common/inet/ip/ip_input.c
index e2e7dca22c..7cfffbc84b 100644
--- a/usr/src/uts/common/inet/ip/ip_input.c
+++ b/usr/src/uts/common/inet/ip/ip_input.c
@@ -1003,8 +1003,26 @@ ire_recv_forward_v4(ire_t *ire, mblk_t *mp, void *iph_arg, ip_recv_attr_t *ira)
 		ira->ira_pktlen = ntohs(ipha->ipha_length);
 	}
 
-	/* Packet is being forwarded. Turning off hwcksum flag. */
-	DB_CKSUMFLAGS(mp) = 0;
+	/*
+	 * The packet came here via MAC-loopback so we must reinstate
+	 * its hardware IP header checksum request.
+	 *
+	 * IP input clears the HCK_IPV4_HDRCKSUM_OK flag. Since
+	 * HCK_IPV4_HDRCKSUM_OK and HCK_IPV4_HDRCKSUM use the same
+	 * value, we end up clearing the client's request to use
+	 * hardware IP header checksum offload. We check for
+	 * HW_LOCAL_MAC and an IP header checksum value of zero as an
+	 * indicator that this packet requires reinstatement of the
+	 * HCK_IPV4_HDRCKSUM flag. That said, zero is a valid
+	 * checksum, and given hardware that doesn't support IP header
+	 * checksum offload, this could result in the checksum being
+	 * computed twice. This is fine because the checksum value is
+	 * zero, and thus will retain its value on recalculation.
+	 */
+	if (((DB_CKSUMFLAGS(mp) & HW_LOCAL_MAC) != 0) &&
+	    ipha->ipha_hdr_checksum == 0) {
+		DB_CKSUMFLAGS(mp) |= HCK_IPV4_HDRCKSUM;
+	}
 
 	/*
 	 * Martian Address Filtering [RFC 1812, Section 5.3.7]
@@ -1138,9 +1156,17 @@ ip_forward_xmit_v4(nce_t *nce, ill_t *ill, mblk_t *mp, ipha_t *ipha,
 		return;
 	}
 	ipha->ipha_ttl--;
-	/* Adjust the checksum to reflect the ttl decrement. */
-	sum = (int)ipha->ipha_hdr_checksum + IP_HDR_CSUM_TTL_ADJUST;
-	ipha->ipha_hdr_checksum = (uint16_t)(sum + (sum >> 16));
+	/*
+	 * Adjust the checksum to reflect the TTL decrement unless
+	 * the packet expects IP header checksum offload; in which
+	 * case we delay its calculation until later. Such a packet
+	 * occurs when it travels via MAC-loopback over a link
+	 * exposing HCKSUM_IPHDRCKSUM.
+	 */
+	if ((DB_CKSUMFLAGS(mp) & HCK_IPV4_HDRCKSUM) == 0) {
+		sum = (int)ipha->ipha_hdr_checksum + IP_HDR_CSUM_TTL_ADJUST;
+		ipha->ipha_hdr_checksum = (uint16_t)(sum + (sum >> 16));
+	}
 
 	/* Check if there are options to update */
 	if (iraflags & IRAF_IPV4_OPTIONS) {
@@ -1175,7 +1201,14 @@ ip_forward_xmit_v4(nce_t *nce, ill_t *ill, mblk_t *mp, ipha_t *ipha,
 
 	ixaflags = IXAF_IS_IPV4 | IXAF_NO_DEV_FLOW_CTL;
 
-	if (pkt_len > mtu) {
+	/*
+	 * If the packet arrived via MAC-loopback, then it might be an
+	 * LSO packet; in this case the MAC layer will take care to
+	 * segment it. Otherwise, we have a normal packet that is
+	 * being forwarded from a source interface with an MTU larger
+	 * than the desination's; in this case IP must fragment it.
+	 */
+	if (pkt_len > mtu && (DB_CKSUMFLAGS(mp) & HW_LSO) == 0) {
 		/*
 		 * It needs fragging on its way out.  If we haven't
 		 * verified the header checksum yet we do it now since
diff --git a/usr/src/uts/common/inet/ip6.h b/usr/src/uts/common/inet/ip6.h
index 4f5b81c12f..01c25b52b5 100644
--- a/usr/src/uts/common/inet/ip6.h
+++ b/usr/src/uts/common/inet/ip6.h
@@ -23,6 +23,7 @@
  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  * Copyright 2014 Nexenta Systems, Inc.  All rights reserved.
+ * Copyright 2019 Joyent, Inc.
  */
 
 #ifndef	_INET_IP6_H
@@ -255,7 +256,7 @@ extern in6_addr_t ip_get_dst_v6(ip6_t *, const mblk_t *, boolean_t *);
 extern ip6_rthdr_t	*ip_find_rthdr_v6(ip6_t *, uint8_t *);
 extern boolean_t	ip_hdr_length_nexthdr_v6(mblk_t *, ip6_t *,
     uint16_t *, uint8_t **);
-extern int	ip_hdr_length_v6(mblk_t *, ip6_t *);
+extern uint16_t	ip_hdr_length_v6(mblk_t *, ip6_t *);
 extern uint32_t	ip_massage_options_v6(ip6_t *, ip6_rthdr_t *, netstack_t *);
 extern void	ip_forward_xmit_v6(nce_t *, mblk_t *, ip6_t *, ip_recv_attr_t *,
     uint32_t, uint32_t);
diff --git a/usr/src/uts/common/io/bridge.c b/usr/src/uts/common/io/bridge.c
index 375d166972..276ad238f2 100644
--- a/usr/src/uts/common/io/bridge.c
+++ b/usr/src/uts/common/io/bridge.c
@@ -23,7 +23,7 @@
  * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  * Copyright (c) 2016 by Delphix. All rights reserved.
- * Copyright 2018 Joyent, Inc.
+ * Copyright 2019 Joyent, Inc.
  */
 
 /*
@@ -2033,7 +2033,7 @@ done:
 
 				KIINCR(bki_forwards);
 				KLPINCR(blpsend, bkl_xmit);
-				MAC_RING_TX(blpsend->bl_mh, NULL, mpsend,
+				mpsend = mac_ring_tx(blpsend->bl_mh, NULL,
 				    mpsend);
 				freemsg(mpsend);
 				mpsend = next;
@@ -2189,7 +2189,7 @@ done:
 					    mpcopy);
 				}
 
-				MAC_RING_TX(blpsend->bl_mh, NULL, mpsend,
+				mpsend = mac_ring_tx(blpsend->bl_mh, NULL,
 				    mpsend);
 				freemsg(mpsend);
 				mpsend = next;
@@ -2571,7 +2571,7 @@ bridge_xmit_cb(mac_handle_t mh, mac_ring_handle_t rh, mblk_t *mpnext)
 	    (blp->bl_flags & BLF_SDUFAIL)))) {
 		KIINCR(bki_sent);
 		KLINCR(bkl_xmit);
-		MAC_RING_TX(blp->bl_mh, rh, mpnext, mp);
+		mp = mac_ring_tx(blp->bl_mh, rh, mpnext);
 		return (mp);
 	}
 
@@ -2629,7 +2629,7 @@ bridge_xmit_cb(mac_handle_t mh, mac_ring_handle_t rh, mblk_t *mpnext)
 			    B_FALSE, B_TRUE);
 		}
 		if (mp != NULL) {
-			MAC_RING_TX(blp->bl_mh, rh, mp, mp);
+			mp = mac_ring_tx(blp->bl_mh, rh, mp);
 			if (mp == NULL) {
 				KIINCR(bki_sent);
 				KLINCR(bkl_xmit);
@@ -2695,7 +2695,7 @@ bridge_trill_decaps(bridge_link_t *blp, mblk_t *mp, uint16_t ingress_nick)
 			/* Deliver a copy locally as well */
 			if ((mpcopy = copymsg(mp)) != NULL)
 				mac_rx_common(blp->bl_mh, NULL, mpcopy);
-			MAC_RING_TX(blp->bl_mh, NULL, mp, mp);
+			mp = mac_ring_tx(blp->bl_mh, NULL, mp);
 		}
 		if (mp == NULL) {
 			KIINCR(bki_sent);
@@ -2716,7 +2716,7 @@ bridge_trill_output(bridge_link_t *blp, mblk_t *mp)
 	bridge_inst_t *bip = blp->bl_inst;	/* used by macros */
 
 	mac_trill_snoop(blp->bl_mh, mp);
-	MAC_RING_TX(blp->bl_mh, NULL, mp, mp);
+	mp = mac_ring_tx(blp->bl_mh, NULL, mp);
 	if (mp == NULL) {
 		KIINCR(bki_sent);
 		KLINCR(bkl_xmit);
diff --git a/usr/src/uts/common/io/fcoe/fcoe_fc.c b/usr/src/uts/common/io/fcoe/fcoe_fc.c
index 42764e48d6..54402b027f 100644
--- a/usr/src/uts/common/io/fcoe/fcoe_fc.c
+++ b/usr/src/uts/common/io/fcoe/fcoe_fc.c
@@ -22,6 +22,7 @@
 /*
  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
+ * Copyright 2019 Joyent, Inc.
  */
 
 /*
@@ -39,6 +40,7 @@
 #include <sys/fcntl.h>
 #include <sys/unistd.h>
 #include <sys/mac_client.h>
+#include <sys/strsubr.h>
 
 /*
  * FCoE header files
@@ -209,6 +211,7 @@ tx_frame:
 	ret_cookie = mac_tx(mac->fm_cli_handle, FRM2MBLK(frm), 0,
 	    MAC_TX_NO_ENQUEUE, &ret_mblk);
 	if (ret_cookie != (mac_tx_cookie_t)NULL) {
+		frm->frm_netb = ret_mblk;
 		mutex_enter(&mac->fm_mutex);
 		(void) cv_reltimedwait(&mac->fm_tx_cv, &mac->fm_mutex,
 		    drv_usectohz(100000), TR_CLOCK_TICK);
@@ -265,7 +268,7 @@ fcoe_alloc_netb(fcoe_port_t *eport, uint32_t fc_frame_size, uint8_t **ppfc)
 static void
 fcoe_free_netb(void *netb)
 {
-	freeb((mblk_t *)netb);
+	freemsgchain((mblk_t *)netb);
 }
 
 fcoe_frame_t *
diff --git a/usr/src/uts/common/io/mac/mac.c b/usr/src/uts/common/io/mac/mac.c
index 12d1e9809c..e748e6d57b 100644
--- a/usr/src/uts/common/io/mac/mac.c
+++ b/usr/src/uts/common/io/mac/mac.c
@@ -1935,8 +1935,7 @@ mac_hwring_send_priv(mac_client_handle_t mch, mac_ring_handle_t rh, mblk_t *mp)
 	mac_client_impl_t *mcip = (mac_client_impl_t *)mch;
 	mac_impl_t *mip = mcip->mci_mip;
 
-	MAC_TX(mip, rh, mp, mcip);
-	return (mp);
+	return (mac_provider_tx(mip, rh, mp, mcip));
 }
 
 /*
@@ -4713,9 +4712,9 @@ mac_group_remmac(mac_group_t *group, const uint8_t *addr)
 }
 
 /*
- * This is the entry point for packets transmitted through the bridging code.
- * If no bridge is in place, MAC_RING_TX transmits using tx ring. The 'rh'
- * pointer may be NULL to select the default ring.
+ * This is the entry point for packets transmitted through the bridge
+ * code. If no bridge is in place, mac_ring_tx() transmits via the tx
+ * ring. The 'rh' pointer may be NULL to select the default ring.
  */
 mblk_t *
 mac_bridge_tx(mac_impl_t *mip, mac_ring_handle_t rh, mblk_t *mp)
@@ -4732,7 +4731,7 @@ mac_bridge_tx(mac_impl_t *mip, mac_ring_handle_t rh, mblk_t *mp)
 		mac_bridge_ref_cb(mh, B_TRUE);
 	mutex_exit(&mip->mi_bridge_lock);
 	if (mh == NULL) {
-		MAC_RING_TX(mip, rh, mp, mp);
+		mp = mac_ring_tx((mac_handle_t)mip, rh, mp);
 	} else {
 		mp = mac_bridge_tx_cb(mh, rh, mp);
 		mac_bridge_ref_cb(mh, B_FALSE);
@@ -8786,3 +8785,52 @@ mac_led_set(mac_handle_t mh, mac_led_mode_t desired)
 
 	return (ret);
 }
+
+/*
+ * Send packets through the Tx ring ('mrh') or through the default
+ * handler if no ring is specified. Before passing the packet down to
+ * the MAC provider, emulate any hardware offloads which have been
+ * requested but are not supported by the provider.
+ */
+mblk_t *
+mac_ring_tx(mac_handle_t mh, mac_ring_handle_t mrh, mblk_t *mp)
+{
+	mac_impl_t *mip = (mac_impl_t *)mh;
+
+	if (mrh == NULL)
+		mrh = mip->mi_default_tx_ring;
+
+	if (mrh == NULL)
+		return (mip->mi_tx(mip->mi_driver, mp));
+	else
+		return (mac_hwring_tx(mrh, mp));
+}
+
+/*
+ * This is the final stop before reaching the underlying MAC provider.
+ * This is also where the bridging hook is inserted. Packets that are
+ * bridged will return through mac_bridge_tx(), with rh nulled out if
+ * the bridge chooses to send output on a different link due to
+ * forwarding.
+ */
+mblk_t *
+mac_provider_tx(mac_impl_t *mip, mac_ring_handle_t rh, mblk_t *mp,
+    mac_client_impl_t *mcip)
+{
+	/*
+	 * If there is a bound Hybrid I/O share, send packets through
+	 * the default tx ring. When there's a bound Hybrid I/O share,
+	 * the tx rings of this client are mapped in the guest domain
+	 * and not accessible from here.
+	 */
+	if (mcip->mci_state_flags & MCIS_SHARE_BOUND)
+		rh = mip->mi_default_tx_ring;
+
+	if (mip->mi_promisc_list != NULL)
+		mac_promisc_dispatch(mip, mp, mcip);
+
+	if (mip->mi_bridge_link == NULL)
+		return (mac_ring_tx((mac_handle_t)mip, rh, mp));
+	else
+		return (mac_bridge_tx(mip, rh, mp));
+}
diff --git a/usr/src/uts/common/io/mac/mac_bcast.c b/usr/src/uts/common/io/mac/mac_bcast.c
index 3b674be1d0..5302b89196 100644
--- a/usr/src/uts/common/io/mac/mac_bcast.c
+++ b/usr/src/uts/common/io/mac/mac_bcast.c
@@ -240,7 +240,8 @@ mac_bcast_send(void *arg1, void *arg2, mblk_t *mp_chain, boolean_t is_loopback)
 		MCIP_STAT_UPDATE(src_mcip, brdcstxmt, 1);
 		MCIP_STAT_UPDATE(src_mcip, brdcstxmtbytes, msgdsize(mp_chain));
 
-		MAC_TX(mip, mip->mi_default_tx_ring, mp_chain, src_mcip);
+		mp_chain = mac_provider_tx(mip, mip->mi_default_tx_ring,
+		    mp_chain, src_mcip);
 		if (mp_chain != NULL)
 			freemsgchain(mp_chain);
 	} else {
diff --git a/usr/src/uts/common/io/mac/mac_client.c b/usr/src/uts/common/io/mac/mac_client.c
index 50316bb81e..d2444094a9 100644
--- a/usr/src/uts/common/io/mac/mac_client.c
+++ b/usr/src/uts/common/io/mac/mac_client.c
@@ -3582,7 +3582,9 @@ mac_tx(mac_client_handle_t mch, mblk_t *mp_chain, uintptr_t hint,
 	srs_tx = &srs->srs_tx;
 	if (srs_tx->st_mode == SRS_TX_DEFAULT &&
 	    (srs->srs_state & SRS_ENQUEUED) == 0 &&
-	    mip->mi_nactiveclients == 1 && mp_chain->b_next == NULL) {
+	    mip->mi_nactiveclients == 1 &&
+	    mp_chain->b_next == NULL &&
+	    (DB_CKSUMFLAGS(mp_chain) & HW_LSO) == 0) {
 		uint64_t	obytes;
 
 		/*
@@ -3623,8 +3625,9 @@ mac_tx(mac_client_handle_t mch, mblk_t *mp_chain, uintptr_t hint,
 		 * receiver -- mark the packet accordingly.
 		 */
 		DB_CKSUMFLAGS(mp_chain) |= HW_LOCAL_MAC;
+		mp_chain = mac_provider_tx(mip, srs_tx->st_arg2, mp_chain,
+		    mcip);
 
-		MAC_TX(mip, srs_tx->st_arg2, mp_chain, mcip);
 		if (mp_chain == NULL) {
 			cookie = 0;
 			SRS_TX_STAT_UPDATE(srs, opackets, 1);
@@ -3636,7 +3639,74 @@ mac_tx(mac_client_handle_t mch, mblk_t *mp_chain, uintptr_t hint,
 			mutex_exit(&srs->srs_lock);
 		}
 	} else {
-		cookie = srs_tx->st_func(srs, mp_chain, hint, flag, ret_mp);
+		mblk_t *mp = mp_chain;
+		mblk_t *new_head = NULL;
+		mblk_t *new_tail = NULL;
+
+		/*
+		 * There are occasions where the packets arriving here
+		 * may request hardware offloads that are not
+		 * available from the underlying MAC provider. This
+		 * currently only happens when a packet is sent across
+		 * the MAC-loopback path of one MAC and then forwarded
+		 * (via IP) to another MAC that lacks one or more of
+		 * the hardware offloads provided by the first one.
+		 * However, in the future, we may choose to pretend
+		 * all MAC providers support all offloads, performing
+		 * emulation on Tx as needed.
+		 *
+		 * We iterate each mblk in-turn, emulating hardware
+		 * offloads as required. From this process, we create
+		 * a new chain. The new chain may be the same as the
+		 * original chain (no hardware emulation needed), a
+		 * collection of new mblks (hardware emulation
+		 * needed), or a mix. At this point, the chain is safe
+		 * for consumption by the underlying MAC provider and
+		 * is passed down to the SRS.
+		 */
+		while (mp != NULL) {
+			mblk_t *next = mp->b_next;
+			mblk_t *tail = NULL;
+			const uint16_t needed =
+			    (DB_CKSUMFLAGS(mp) ^ mip->mi_tx_cksum_flags) &
+			    DB_CKSUMFLAGS(mp);
+
+			mp->b_next = NULL;
+
+			if (needed != 0) {
+				mac_emul_t emul = 0;
+
+				if (needed & HCK_IPV4_HDRCKSUM)
+					emul |= MAC_IPCKSUM_EMUL;
+				if (needed & (HCK_PARTIALCKSUM | HCK_FULLCKSUM))
+					emul |= MAC_HWCKSUM_EMUL;
+				if (needed & HW_LSO)
+					emul = MAC_LSO_EMUL;
+
+				mac_hw_emul(&mp, &tail, NULL, emul);
+
+				if (mp == NULL) {
+					mp = next;
+					continue;
+				}
+			}
+
+			if (new_head == NULL) {
+				new_head = mp;
+			} else {
+				new_tail->b_next = mp;
+			}
+
+			new_tail = (tail == NULL) ? mp : tail;
+			mp = next;
+		}
+
+		if (new_head == NULL) {
+			cookie = 0;
+			goto done;
+		}
+
+		cookie = srs_tx->st_func(srs, new_head, hint, flag, ret_mp);
 	}
 
 done:
diff --git a/usr/src/uts/common/io/mac/mac_provider.c b/usr/src/uts/common/io/mac/mac_provider.c
index cb1a76aef6..99f2f3431e 100644
--- a/usr/src/uts/common/io/mac/mac_provider.c
+++ b/usr/src/uts/common/io/mac/mac_provider.c
@@ -112,6 +112,37 @@ mac_free(mac_register_t *mregp)
 }
 
 /*
+ * Convert a MAC's offload features into the equivalent DB_CKSUMFLAGS
+ * value.
+ */
+static uint16_t
+mac_features_to_flags(mac_handle_t mh)
+{
+	uint16_t flags = 0;
+	uint32_t cap_sum = 0;
+	mac_capab_lso_t cap_lso;
+
+	if (mac_capab_get(mh, MAC_CAPAB_HCKSUM, &cap_sum)) {
+		if (cap_sum & HCKSUM_IPHDRCKSUM)
+			flags |= HCK_IPV4_HDRCKSUM;
+
+		if (cap_sum & HCKSUM_INET_PARTIAL)
+			flags |= HCK_PARTIALCKSUM;
+		else if (cap_sum & (HCKSUM_INET_FULL_V4 | HCKSUM_INET_FULL_V6))
+			flags |= HCK_FULLCKSUM;
+	}
+
+	/*
+	 * We don't need the information stored in 'cap_lso', but we
+	 * need to pass a non-NULL pointer to appease the driver.
+	 */
+	if (mac_capab_get(mh, MAC_CAPAB_LSO, &cap_lso))
+		flags |= HW_LSO;
+
+	return (flags);
+}
+
+/*
  * mac_register() is how drivers register new MACs with the GLDv3
  * framework.  The mregp argument is allocated by drivers using the
  * mac_alloc() function, and can be freed using mac_free() immediately upon
@@ -341,9 +372,13 @@ mac_register(mac_register_t *mregp, mac_handle_t *mhp)
 	    mip, 0, &p0, TS_RUN, minclsyspri);
 
 	/*
-	 * Initialize the capabilities
+	 * Cache the DB_CKSUMFLAGS that this MAC supports.
 	 */
+	mip->mi_tx_cksum_flags = mac_features_to_flags((mac_handle_t)mip);
 
+	/*
+	 * Initialize the capabilities
+	 */
 	bzero(&mip->mi_rx_rings_cap, sizeof (mac_capab_rings_t));
 	bzero(&mip->mi_tx_rings_cap, sizeof (mac_capab_rings_t));
 
diff --git a/usr/src/uts/common/io/mac/mac_sched.c b/usr/src/uts/common/io/mac/mac_sched.c
index 0e62f828a9..c4086d6bb6 100644
--- a/usr/src/uts/common/io/mac/mac_sched.c
+++ b/usr/src/uts/common/io/mac/mac_sched.c
@@ -1348,7 +1348,7 @@ int mac_srs_worker_wakeup_ticks = 0;
 		mutex_exit(&srs->srs_bw->mac_bw_lock);
 
 #define	MAC_TX_SRS_DROP_MESSAGE(srs, chain, cookie, s) {	\
-	mac_drop_pkt((chain), (s));				\
+	mac_drop_chain((chain), (s));				\
 	/* increment freed stats */				\
 	(srs)->srs_tx.st_stat.mts_sdrops++;			\
 	(cookie) = (mac_tx_cookie_t)(srs);			\
@@ -4355,7 +4355,7 @@ mac_tx_send(mac_client_handle_t mch, mac_ring_handle_t ring, mblk_t *mp_chain,
 			 */
 			DB_CKSUMFLAGS(mp) |= HW_LOCAL_MAC;
 			CHECK_VID_AND_ADD_TAG(mp);
-			MAC_TX(mip, ring, mp, src_mcip);
+			mp = mac_provider_tx(mip, ring, mp, src_mcip);
 
 			/*
 			 * If the driver is out of descriptors and does a
@@ -4467,7 +4467,7 @@ mac_tx_send(mac_client_handle_t mch, mac_ring_handle_t ring, mblk_t *mp_chain,
 			 * Unknown destination, send via the underlying
 			 * NIC.
 			 */
-			MAC_TX(mip, ring, mp, src_mcip);
+			mp = mac_provider_tx(mip, ring, mp, src_mcip);
 			if (mp != NULL) {
 				/*
 				 * Adjust for the last packet that
diff --git a/usr/src/uts/common/io/mac/mac_util.c b/usr/src/uts/common/io/mac/mac_util.c
index 334d1d034b..61671a8886 100644
--- a/usr/src/uts/common/io/mac/mac_util.c
+++ b/usr/src/uts/common/io/mac/mac_util.c
@@ -50,6 +50,7 @@
 #include <inet/ipsecah.h>
 #include <inet/tcp.h>
 #include <inet/udp_impl.h>
+#include <inet/sctp_ip.h>
 
 /*
  * The next two functions are used for dropping packets or chains of
@@ -157,6 +158,208 @@ mac_copymsgchain_cksum(mblk_t *mp)
 }
 
 /*
+ * Calculate the ULP checksum for IPv4. Return true if the calculation
+ * was successful, or false if an error occurred. If the later, place
+ * an error message into '*err'.
+ */
+static boolean_t
+mac_sw_cksum_ipv4(mblk_t *mp, uint32_t ip_hdr_offset, ipha_t *ipha,
+    const char **err)
+{
+	const uint8_t proto = ipha->ipha_protocol;
+	size_t len;
+	const uint32_t ip_hdr_sz = IPH_HDR_LENGTH(ipha);
+	/* ULP offset from start of L2. */
+	const uint32_t ulp_offset = ip_hdr_offset + ip_hdr_sz;
+	ipaddr_t src, dst;
+	uint32_t cksum;
+	uint16_t *up;
+
+	/*
+	 * We need a pointer to the ULP checksum. We're assuming the
+	 * ULP checksum pointer resides in the first mblk. Our native
+	 * TCP stack should always put the headers in the first mblk,
+	 * but currently we have no way to guarantee that other
+	 * clients don't spread headers (or even header fields) across
+	 * mblks.
+	 */
+	switch (proto) {
+	case IPPROTO_TCP:
+		ASSERT3U(MBLKL(mp), >=, (ulp_offset + sizeof (tcph_t)));
+		if (MBLKL(mp) < (ulp_offset + sizeof (tcph_t))) {
+			*err = "mblk doesn't contain TCP header";
+			goto bail;
+		}
+
+		up = IPH_TCPH_CHECKSUMP(ipha, ip_hdr_sz);
+		cksum = IP_TCP_CSUM_COMP;
+		break;
+
+	case IPPROTO_UDP:
+		ASSERT3U(MBLKL(mp), >=, (ulp_offset + sizeof (udpha_t)));
+		if (MBLKL(mp) < (ulp_offset + sizeof (udpha_t))) {
+			*err = "mblk doesn't contain UDP header";
+			goto bail;
+		}
+
+		up = IPH_UDPH_CHECKSUMP(ipha, ip_hdr_sz);
+		cksum = IP_UDP_CSUM_COMP;
+		break;
+
+	case IPPROTO_SCTP: {
+		sctp_hdr_t *sctph;
+
+		ASSERT3U(MBLKL(mp), >=, (ulp_offset + sizeof (sctp_hdr_t)));
+		if (MBLKL(mp) < (ulp_offset + sizeof (sctp_hdr_t))) {
+			*err = "mblk doesn't contain SCTP header";
+			goto bail;
+		}
+
+		sctph = (sctp_hdr_t *)(mp->b_rptr + ulp_offset);
+		sctph->sh_chksum = 0;
+		sctph->sh_chksum = sctp_cksum(mp, ulp_offset);
+		return (B_TRUE);
+	}
+
+	default:
+		*err = "unexpected protocol";
+		goto bail;
+
+	}
+
+	/* Pseudo-header checksum. */
+	src = ipha->ipha_src;
+	dst = ipha->ipha_dst;
+	len = ntohs(ipha->ipha_length) - ip_hdr_sz;
+
+	cksum += (dst >> 16) + (dst & 0xFFFF) + (src >> 16) + (src & 0xFFFF);
+	cksum += htons(len);
+
+	/*
+	 * We have already accounted for the pseudo checksum above.
+	 * Make sure the ULP checksum field is zero before computing
+	 * the rest.
+	 */
+	*up = 0;
+	cksum = IP_CSUM(mp, ulp_offset, cksum);
+	*up = (uint16_t)(cksum ? cksum : ~cksum);
+
+	return (B_TRUE);
+
+bail:
+	return (B_FALSE);
+}
+
+/*
+ * Calculate the ULP checksum for IPv6. Return true if the calculation
+ * was successful, or false if an error occurred. If the later, place
+ * an error message into '*err'.
+ */
+static boolean_t
+mac_sw_cksum_ipv6(mblk_t *mp, uint32_t ip_hdr_offset, const char **err)
+{
+	ip6_t* ip6h = (ip6_t *)(mp->b_rptr + ip_hdr_offset);
+	const uint8_t proto = ip6h->ip6_nxt;
+	const uint16_t *iphs = (uint16_t *)ip6h;
+	/* ULP offset from start of L2. */
+	uint32_t ulp_offset;
+	size_t len;
+	uint32_t cksum;
+	uint16_t *up;
+	uint16_t ip_hdr_sz;
+
+	if (!ip_hdr_length_nexthdr_v6(mp, ip6h, &ip_hdr_sz, NULL)) {
+		*err = "malformed IPv6 header";
+		goto bail;
+	}
+
+	ulp_offset = ip_hdr_offset + ip_hdr_sz;
+
+	/*
+	 * We need a pointer to the ULP checksum. We're assuming the
+	 * ULP checksum pointer resides in the first mblk. Our native
+	 * TCP stack should always put the headers in the first mblk,
+	 * but currently we have no way to guarantee that other
+	 * clients don't spread headers (or even header fields) across
+	 * mblks.
+	 */
+	switch (proto) {
+	case IPPROTO_TCP:
+		ASSERT3U(MBLKL(mp), >=, (ulp_offset + sizeof (tcph_t)));
+		if (MBLKL(mp) < (ulp_offset + sizeof (tcph_t))) {
+			*err = "mblk doesn't contain TCP header";
+			goto bail;
+		}
+
+		up = IPH_TCPH_CHECKSUMP(ip6h, ip_hdr_sz);
+		cksum = IP_TCP_CSUM_COMP;
+		break;
+
+	case IPPROTO_UDP:
+		ASSERT3U(MBLKL(mp), >=, (ulp_offset + sizeof (udpha_t)));
+		if (MBLKL(mp) < (ulp_offset + sizeof (udpha_t))) {
+			*err = "mblk doesn't contain UDP header";
+			goto bail;
+		}
+
+		up = IPH_UDPH_CHECKSUMP(ip6h, ip_hdr_sz);
+		cksum = IP_UDP_CSUM_COMP;
+		break;
+
+	case IPPROTO_SCTP: {
+		sctp_hdr_t *sctph;
+
+		ASSERT3U(MBLKL(mp), >=, (ulp_offset + sizeof (sctp_hdr_t)));
+		if (MBLKL(mp) < (ulp_offset + sizeof (sctp_hdr_t))) {
+			*err = "mblk doesn't contain SCTP header";
+			goto bail;
+		}
+
+		sctph = (sctp_hdr_t *)(mp->b_rptr + ulp_offset);
+		/*
+		 * Zero out the checksum field to ensure proper
+		 * checksum calculation.
+		 */
+		sctph->sh_chksum = 0;
+		sctph->sh_chksum = sctp_cksum(mp, ulp_offset);
+		return (B_TRUE);
+	}
+
+	default:
+		*err = "unexpected protocol";
+		goto bail;
+	}
+
+	/*
+	 * The payload length includes the payload and the IPv6
+	 * extension headers; the idea is to subtract the extension
+	 * header length to get the real payload length.
+	 */
+	len = ntohs(ip6h->ip6_plen) - (ip_hdr_sz - IPV6_HDR_LEN);
+	cksum += len;
+
+	/*
+	 * We accumulate the pseudo header checksum in cksum; then we
+	 * call IP_CSUM to compute the checksum over the payload.
+	 */
+	cksum += iphs[4] + iphs[5] + iphs[6] + iphs[7] + iphs[8] + iphs[9] +
+	    iphs[10] + iphs[11] + iphs[12] + iphs[13] + iphs[14] + iphs[15] +
+	    iphs[16] + iphs[17] + iphs[18] + iphs[19];
+	cksum = IP_CSUM(mp, ulp_offset, cksum);
+
+	/* For UDP/IPv6 a zero UDP checksum is not allowed. Change to 0xffff */
+	if (proto == IPPROTO_UDP && cksum == 0)
+		cksum = ~cksum;
+
+	*up = (uint16_t)cksum;
+
+	return (B_TRUE);
+
+bail:
+	return (B_FALSE);
+}
+
+/*
  * Perform software checksum on a single message, if needed. The
  * emulation performed is determined by an intersection of the mblk's
  * flags and the emul flags requested. The emul flags are documented
@@ -167,12 +370,10 @@ mac_sw_cksum(mblk_t *mp, mac_emul_t emul)
 {
 	mblk_t *skipped_hdr = NULL;
 	uint32_t flags, start, stuff, end, value;
-	uint16_t len;
-	uint32_t offset;
+	uint32_t ip_hdr_offset;
 	uint16_t etype;
+	size_t ip_hdr_sz;
 	struct ether_header *ehp;
-	ipha_t *ipha;
-	uint8_t proto;
 	const char *err = "";
 
 	/*
@@ -202,21 +403,31 @@ mac_sw_cksum(mblk_t *mp, mac_emul_t emul)
 
 		evhp = (struct ether_vlan_header *)mp->b_rptr;
 		etype = ntohs(evhp->ether_type);
-		offset = sizeof (struct ether_vlan_header);
+		ip_hdr_offset = sizeof (struct ether_vlan_header);
 	} else {
 		etype = ntohs(ehp->ether_type);
-		offset = sizeof (struct ether_header);
+		ip_hdr_offset = sizeof (struct ether_header);
 	}
 
 	/*
-	 * If this packet isn't IPv4, then leave it alone. We still
-	 * need to add IPv6 support and we don't want to affect non-IP
-	 * traffic like ARP.
+	 * If this packet isn't IP, then leave it alone. We don't want
+	 * to affect non-IP traffic like ARP. Assume the IP header
+	 * doesn't include any options, for now. We will use the
+	 * correct size later after we know there are enough bytes to
+	 * at least fill out the basic header.
 	 */
-	if (etype != ETHERTYPE_IP)
+	switch (etype) {
+	case ETHERTYPE_IP:
+		ip_hdr_sz = sizeof (ipha_t);
+		break;
+	case ETHERTYPE_IPV6:
+		ip_hdr_sz = sizeof (ip6_t);
+		break;
+	default:
 		return (mp);
+	}
 
-	ASSERT3U(MBLKL(mp), >=, offset);
+	ASSERT3U(MBLKL(mp), >=, ip_hdr_offset);
 
 	/*
 	 * If the first mblk of this packet contains only the ethernet
@@ -224,8 +435,8 @@ mac_sw_cksum(mblk_t *mp, mac_emul_t emul)
 	 * contained in only a single mblk can then use the fastpaths
 	 * tuned to that possibility.
 	 */
-	if (MBLKL(mp) == offset) {
-		offset -= MBLKL(mp);
+	if (MBLKL(mp) == ip_hdr_offset) {
+		ip_hdr_offset -= MBLKL(mp);
 		/* This is guaranteed by mac_hw_emul(). */
 		ASSERT3P(mp->b_cont, !=, NULL);
 		skipped_hdr = mp;
@@ -238,8 +449,8 @@ mac_sw_cksum(mblk_t *mp, mac_emul_t emul)
 	 * this assumption but it's prudent to guard our future
 	 * clients that might not honor this contract.
 	 */
-	ASSERT3U(MBLKL(mp), >=, offset + sizeof (ipha_t));
-	if (MBLKL(mp) < (offset + sizeof (ipha_t))) {
+	ASSERT3U(MBLKL(mp), >=, ip_hdr_offset + ip_hdr_sz);
+	if (MBLKL(mp) < (ip_hdr_offset + ip_hdr_sz)) {
 		err = "mblk doesn't contain IP header";
 		goto bail;
 	}
@@ -268,86 +479,12 @@ mac_sw_cksum(mblk_t *mp, mac_emul_t emul)
 		mp = tmp;
 	}
 
-	ipha = (ipha_t *)(mp->b_rptr + offset);
+	if (etype == ETHERTYPE_IP) {
+		ipha_t *ipha = (ipha_t *)(mp->b_rptr + ip_hdr_offset);
 
-	/*
-	 * This code assumes a "simple" IP header (20 bytes, no
-	 * options). IPv4 options are mostly a historic artifact. The
-	 * one slight exception is Router Alert, but we don't expect
-	 * such a packet to land here.
-	 */
-	proto = ipha->ipha_protocol;
-	ASSERT(ipha->ipha_version_and_hdr_length == IP_SIMPLE_HDR_VERSION);
-	if (ipha->ipha_version_and_hdr_length != IP_SIMPLE_HDR_VERSION) {
-		err = "not simple IP header";
-		goto bail;
-	}
-
-	switch (proto) {
-	case IPPROTO_TCP:
-		ASSERT3U(MBLKL(mp), >=,
-		    (offset + sizeof (ipha_t) + sizeof (tcph_t)));
-		if (MBLKL(mp) < (offset + sizeof (ipha_t) + sizeof (tcph_t))) {
-			err = "mblk doesn't contain TCP header";
-			goto bail;
-		}
-		break;
-
-	case IPPROTO_UDP:
-		ASSERT3U(MBLKL(mp), >=,
-		    (offset + sizeof (ipha_t) + sizeof (udpha_t)));
-		if (MBLKL(mp) < (offset + sizeof (ipha_t) + sizeof (udpha_t))) {
-			err = "mblk doesn't contain UDP header";
-			goto bail;
-		}
-		break;
-
-	default:
-		err = "unexpected protocol";
-		goto bail;
-	}
-
-	if (flags & (HCK_FULLCKSUM | HCK_IPV4_HDRCKSUM)) {
 		if ((flags & HCK_FULLCKSUM) && (emul & MAC_HWCKSUM_EMUL)) {
-			ipaddr_t src, dst;
-			uint32_t cksum;
-			uint16_t *up;
-
-			/* Get a pointer to the ULP checksum. */
-			switch (proto) {
-			case IPPROTO_TCP:
-				/* LINTED: improper alignment cast */
-				up = IPH_TCPH_CHECKSUMP(ipha,
-				    IP_SIMPLE_HDR_LENGTH);
-				break;
-
-			case IPPROTO_UDP:
-				/* LINTED: improper alignment cast */
-				up = IPH_UDPH_CHECKSUMP(ipha,
-				    IP_SIMPLE_HDR_LENGTH);
-				break;
-			}
-
-			/* Pseudo-header checksum. */
-			src = ipha->ipha_src;
-			dst = ipha->ipha_dst;
-			len = ntohs(ipha->ipha_length) - IP_SIMPLE_HDR_LENGTH;
-
-			cksum = (dst >> 16) + (dst & 0xFFFF) +
-			    (src >> 16) + (src & 0xFFFF);
-			cksum += htons(len);
-
-			/*
-			 * The checksum value stored in the packet
-			 * needs to be correct. Compute it here.
-			 */
-			*up = 0;
-			cksum += (((proto) == IPPROTO_UDP) ?
-			    IP_UDP_CSUM_COMP : IP_TCP_CSUM_COMP);
-			cksum = IP_CSUM(mp, IP_SIMPLE_HDR_LENGTH +
-			    offset, cksum);
-			*(up) = (uint16_t)(cksum ? cksum : ~cksum);
-
+			if (!mac_sw_cksum_ipv4(mp, ip_hdr_offset, ipha, &err))
+				goto bail;
 		}
 
 		/* We always update the ULP checksum flags. */
@@ -358,47 +495,54 @@ mac_sw_cksum(mblk_t *mp, mac_emul_t emul)
 		}
 
 		/*
-		 * Out of paranoia, and for the sake of correctness,
-		 * we won't calulate the IP header checksum if it's
-		 * already populated. While unlikely, it's possible to
-		 * write code that might end up calling mac_sw_cksum()
-		 * twice on the same mblk (performing both LSO and
-		 * checksum emualtion in a single mblk chain loop --
-		 * the LSO emulation inserts a new chain into the
-		 * existing chain and then the loop iterates back over
-		 * the new segments and emulates the checksum a second
-		 * time). Normally this wouldn't be a problem, because
-		 * the HCK_*_OK flags are supposed to indicate that we
+		 * While unlikely, it's possible to write code that
+		 * might end up calling mac_sw_cksum() twice on the
+		 * same mblk (performing both LSO and checksum
+		 * emualtion in a single mblk chain loop -- the LSO
+		 * emulation inserts a new chain into the existing
+		 * chain and then the loop iterates back over the new
+		 * segments and emulates the checksum a second time).
+		 * Normally this wouldn't be a problem, because the
+		 * HCK_*_OK flags are supposed to indicate that we
 		 * don't need to do peform the work. But
 		 * HCK_IPV4_HDRCKSUM and HCK_IPV4_HDRCKSUM_OK have the
 		 * same value; so we cannot use these flags to
 		 * determine if the IP header checksum has already
-		 * been calculated or not. Luckily, if IP requests
-		 * HCK_IPV4_HDRCKSUM, then the IP header checksum will
-		 * be zero. So this test works just as well as
-		 * checking the flag. However, in the future, we
+		 * been calculated or not. For this reason, we zero
+		 * out the the checksum first. In the future, we
 		 * should fix the HCK_* flags.
 		 */
-		if ((flags & HCK_IPV4_HDRCKSUM) && (emul & MAC_HWCKSUM_EMULS) &&
-		    ipha->ipha_hdr_checksum == 0) {
+		if ((flags & HCK_IPV4_HDRCKSUM) && (emul & MAC_HWCKSUM_EMULS)) {
+			ipha->ipha_hdr_checksum = 0;
 			ipha->ipha_hdr_checksum = (uint16_t)ip_csum_hdr(ipha);
 			flags &= ~HCK_IPV4_HDRCKSUM;
 			flags |= HCK_IPV4_HDRCKSUM_OK;
 		}
+	} else if (etype == ETHERTYPE_IPV6) {
+		/* There is no IP header checksum for IPv6. */
+		if ((flags & HCK_FULLCKSUM) && (emul & MAC_HWCKSUM_EMUL)) {
+			if (!mac_sw_cksum_ipv6(mp, ip_hdr_offset, &err))
+				goto bail;
+			flags &= ~HCK_FULLCKSUM;
+			flags |= HCK_FULLCKSUM_OK;
+			value = 0;
+		}
 	}
 
+	/*
+	 * Partial checksum is the same for both IPv4 and IPv6.
+	 */
 	if ((flags & HCK_PARTIALCKSUM) && (emul & MAC_HWCKSUM_EMUL)) {
 		uint16_t *up, partial, cksum;
 		uchar_t *ipp; /* ptr to beginning of IP header */
 
-		ipp = mp->b_rptr + offset;
-		/* LINTED: cast may result in improper alignment */
+		ipp = mp->b_rptr + ip_hdr_offset;
 		up = (uint16_t *)((uchar_t *)ipp + stuff);
 		partial = *up;
 		*up = 0;
 
 		ASSERT3S(end, >, start);
-		cksum = ~IP_CSUM_PARTIAL(mp, offset + start, partial);
+		cksum = ~IP_CSUM_PARTIAL(mp, ip_hdr_offset + start, partial);
 		*up = cksum != 0 ? cksum : ~cksum;
 	}
 
@@ -1169,13 +1313,8 @@ fail:
  *    can't directly handle LSO packets or packets without fully
  *    calculated checksums.
  *
- * 2. A way for MAC providers (drivers) to offer LSO even when the
- *    underlying HW can't or won't supply LSO offload.
- *
- * At the time of this writing no provider is making use of this
- * function. However, the plan for the future is to always assume LSO
- * is available and then add SW LSO emulation to all providers that
- * don't support it in HW.
+ * 2. A way for MAC to offer hardware offloads when the underlying
+ *    hardware can't or won't.
  */
 void
 mac_hw_emul(mblk_t **mp_chain, mblk_t **otail, uint_t *ocount, mac_emul_t emul)
diff --git a/usr/src/uts/common/io/simnet/simnet.c b/usr/src/uts/common/io/simnet/simnet.c
index 9bfe2fe7cf..8459a02d46 100644
--- a/usr/src/uts/common/io/simnet/simnet.c
+++ b/usr/src/uts/common/io/simnet/simnet.c
@@ -22,7 +22,7 @@
  * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  *
- * Copyright 2018 Joyent, Inc.
+ * Copyright 2019 Joyent, Inc.
  */
 
 /*
@@ -53,6 +53,7 @@
 #include <sys/atomic.h>
 #include <sys/mac_wifi.h>
 #include <sys/mac_impl.h>
+#include <sys/pattr.h>
 #include <inet/wifi_ioctl.h>
 #include <sys/thread.h>
 #include <sys/synch.h>
@@ -109,14 +110,15 @@ static int simnet_m_stat(void *, uint_t, uint64_t *);
 static void simnet_m_ioctl(void *, queue_t *, mblk_t *);
 static mblk_t *simnet_m_tx(void *, mblk_t *);
 static int simnet_m_setprop(void *, const char *, mac_prop_id_t,
-    uint_t, const void *);
+    const uint_t, const void *);
 static int simnet_m_getprop(void *, const char *, mac_prop_id_t,
     uint_t, void *);
 static void simnet_m_propinfo(void *, const char *, mac_prop_id_t,
     mac_prop_info_handle_t);
+static boolean_t simnet_m_getcapab(void *, mac_capab_t, void *);
 
 static mac_callbacks_t simnet_m_callbacks = {
-	(MC_IOCTL | MC_SETPROP | MC_GETPROP | MC_PROPINFO),
+	(MC_IOCTL | MC_GETCAPAB | MC_SETPROP | MC_GETPROP | MC_PROPINFO),
 	simnet_m_stat,
 	simnet_m_start,
 	simnet_m_stop,
@@ -126,7 +128,7 @@ static mac_callbacks_t simnet_m_callbacks = {
 	simnet_m_tx,
 	NULL,
 	simnet_m_ioctl,
-	NULL,
+	simnet_m_getcapab,
 	NULL,
 	NULL,
 	simnet_m_setprop,
@@ -673,6 +675,13 @@ simnet_thread_unref(simnet_dev_t *sdev)
 	mutex_exit(&sdev->sd_instlock);
 }
 
+/*
+ * TODO: Add properties to set Rx checksum flag behavior.
+ *
+ * o HCK_IPV4_HDRCKSUM_OK.
+ * o HCK_PARTIALCKSUM.
+ * o HCK_FULLCKSUM_OK.
+ */
 static void
 simnet_rx(void *arg)
 {
@@ -685,7 +694,7 @@ simnet_rx(void *arg)
 
 	/* Check for valid packet header */
 	if (mac_header_info(sdev->sd_mh, mp, &hdr_info) != 0) {
-		freemsg(mp);
+		mac_drop_pkt(mp, "invalid L2 header");
 		sdev->sd_stats.recv_errors++;
 		goto rx_done;
 	}
@@ -727,13 +736,13 @@ simnet_m_tx(void *arg, mblk_t *mp_chain)
 	simnet_dev_t *sdev = arg;
 	simnet_dev_t *sdev_rx;
 	mblk_t *mpnext = mp_chain;
-	mblk_t *mp;
+	mblk_t *mp, *nmp;
 
 	rw_enter(&simnet_dev_lock, RW_READER);
 	if ((sdev_rx = sdev->sd_peer_dev) == NULL) {
 		/* Discard packets when no peer exists */
 		rw_exit(&simnet_dev_lock);
-		freemsgchain(mp_chain);
+		mac_drop_chain(mp_chain, "no peer");
 		return (NULL);
 	}
 
@@ -750,20 +759,20 @@ simnet_m_tx(void *arg, mblk_t *mp_chain)
 	 */
 	if (!simnet_thread_ref(sdev_rx)) {
 		rw_exit(&simnet_dev_lock);
-		freemsgchain(mp_chain);
+		mac_drop_chain(mp_chain, "simnet peer dev not ready");
 		return (NULL);
 	}
 	rw_exit(&simnet_dev_lock);
 
 	if (!simnet_thread_ref(sdev)) {
 		simnet_thread_unref(sdev_rx);
-		freemsgchain(mp_chain);
+		mac_drop_chain(mp_chain, "simnet dev not ready");
 		return (NULL);
 	}
 
 	while ((mp = mpnext) != NULL) {
-		int len;
-		int size;
+		size_t len;
+		size_t size;
 		mblk_t *mp_new;
 		mblk_t *mp_tmp;
 
@@ -777,7 +786,7 @@ simnet_m_tx(void *arg, mblk_t *mp_chain)
 			mp_new = allocb(size, BPRI_HI);
 			if (mp_new == NULL) {
 				sdev->sd_stats.xmit_errors++;
-				freemsg(mp);
+				mac_drop_pkt(mp, "allocb failed");
 				continue;
 			}
 			bzero(mp_new->b_wptr, size);
@@ -791,19 +800,36 @@ simnet_m_tx(void *arg, mblk_t *mp_chain)
 		}
 
 		/* Pullup packet into a single mblk */
-		if (!pullupmsg(mp, -1)) {
+		if ((nmp = msgpullup(mp, -1)) == NULL) {
 			sdev->sd_stats.xmit_errors++;
-			freemsg(mp);
+			mac_drop_pkt(mp, "msgpullup failed");
 			continue;
+		} else {
+			mac_hcksum_clone(mp, nmp);
+			freemsg(mp);
+			mp = nmp;
 		}
 
 		/* Hold reference for taskq receive processing per-pkt */
 		if (!simnet_thread_ref(sdev_rx)) {
-			freemsg(mp);
-			freemsgchain(mpnext);
+			mac_drop_pkt(mp, "failed to get thread ref");
+			mac_drop_chain(mpnext, "failed to get thread ref");
 			break;
 		}
 
+		mac_hw_emul(&mp, NULL, NULL,
+		    MAC_IPCKSUM_EMUL | MAC_HWCKSUM_EMUL | MAC_LSO_EMUL);
+		if (mp == NULL) {
+			sdev->sd_stats.xmit_errors++;
+			continue;
+		}
+
+		/*
+		 * Remember, we are emulating a real NIC here; the
+		 * checksum flags can't make the trip across the link.
+		 */
+		DB_CKSUMFLAGS(mp) = 0;
+
 		/* Use taskq for pkt receive to avoid kernel stack explosion */
 		mp->b_next = (mblk_t *)sdev_rx;
 		if (ddi_taskq_dispatch(simnet_rxq, simnet_rx, mp,
@@ -882,6 +908,43 @@ simnet_m_ioctl(void *arg, queue_t *q, mblk_t *mp)
 	miocack(q, mp, msgdsize(mp1), rc);
 }
 
+static boolean_t
+simnet_m_getcapab(void *arg, mac_capab_t cap, void *cap_data)
+{
+	simnet_dev_t *sdev = arg;
+	const uint_t tcp_cksums = HCKSUM_INET_FULL_V4 | HCKSUM_INET_PARTIAL;
+
+	switch (cap) {
+	case MAC_CAPAB_HCKSUM: {
+		uint32_t *tx_cksum_flags = cap_data;
+		*tx_cksum_flags = sdev->sd_tx_cksum;
+		break;
+	}
+	case MAC_CAPAB_LSO: {
+		mac_capab_lso_t *cap_lso = cap_data;
+
+		if (sdev->sd_lso &&
+		    (sdev->sd_tx_cksum & HCKSUM_IPHDRCKSUM) != 0 &&
+		    (sdev->sd_tx_cksum & tcp_cksums) != 0) {
+			/*
+			 * The LSO configuration is hardwried for now,
+			 * but there's no reason we couldn't also make
+			 * this configurable in the future.
+			 */
+			cap_lso->lso_flags = LSO_TX_BASIC_TCP_IPV4;
+			cap_lso->lso_basic_tcp_ipv4.lso_max = SD_LSO_MAXLEN;
+			break;
+		} else {
+			return (B_FALSE);
+		}
+	}
+	default:
+		return (B_FALSE);
+	}
+
+	return (B_TRUE);
+}
+
 static int
 simnet_m_stat(void *arg, uint_t stat, uint64_t *val)
 {
@@ -1138,20 +1201,20 @@ set_wl_esslist_priv_prop(simnet_wifidev_t *wdev, uint_t pr_valsize,
 }
 
 static int
-simnet_set_priv_prop(simnet_dev_t *sdev, const char *pr_name,
-    uint_t pr_valsize, const void *pr_val)
+simnet_set_priv_prop_wifi(simnet_dev_t *sdev, const char *name,
+    const uint_t len, const void *val)
 {
 	simnet_wifidev_t *wdev = sdev->sd_wifidev;
 	long result;
 
-	if (strcmp(pr_name, "_wl_esslist") == 0) {
-		if (pr_val == NULL)
+	if (strcmp(name, "_wl_esslist") == 0) {
+		if (val == NULL)
 			return (EINVAL);
-		return (set_wl_esslist_priv_prop(wdev, pr_valsize, pr_val));
-	} else if (strcmp(pr_name, "_wl_connected") == 0) {
-		if (pr_val == NULL)
+		return (set_wl_esslist_priv_prop(wdev, len, val));
+	} else if (strcmp(name, "_wl_connected") == 0) {
+		if (val == NULL)
 			return (EINVAL);
-		(void) ddi_strtol(pr_val, (char **)NULL, 0, &result);
+		(void) ddi_strtol(val, (char **)NULL, 0, &result);
 		wdev->swd_linkstatus = ((result == 1) ?
 		    WL_CONNECTED:WL_NOTCONNECTED);
 		return (0);
@@ -1160,37 +1223,76 @@ simnet_set_priv_prop(simnet_dev_t *sdev, const char *pr_name,
 	return (EINVAL);
 }
 
+/* ARGSUSED */
 static int
-simnet_m_setprop(void *arg, const char *pr_name, mac_prop_id_t wldp_pr_num,
-    uint_t wldp_length, const void *wldp_buf)
+simnet_set_priv_prop_ether(simnet_dev_t *sdev, const char *name,
+    const uint_t len, const void *val)
 {
-	simnet_dev_t *sdev = arg;
-	simnet_wifidev_t *wdev = sdev->sd_wifidev;
-	int err = 0;
-	uint32_t mtu;
+	if (strcmp(name, SD_PROP_TX_ULP_CKSUM) == 0) {
+		if (val == NULL)
+			return (EINVAL);
 
-	switch (wldp_pr_num) {
-	case MAC_PROP_MTU:
-		(void) memcpy(&mtu, wldp_buf, sizeof (mtu));
-		if (mtu > ETHERMIN && mtu < SIMNET_MAX_MTU)
-			return (mac_maxsdu_update(sdev->sd_mh, mtu));
-		else
+		/*
+		 * Remember, full and partial checksum are mutually
+		 * exclusive.
+		 */
+		if (strcmp(val, "none") == 0) {
+			sdev->sd_tx_cksum &= ~HCKSUM_INET_FULL_V4;
+		} else if (strcmp(val, "fullv4") == 0) {
+			sdev->sd_tx_cksum &= ~HCKSUM_INET_PARTIAL;
+			sdev->sd_tx_cksum |= HCKSUM_INET_FULL_V4;
+		} else if (strcmp(val, "partial") == 0) {
+			sdev->sd_tx_cksum &= HCKSUM_INET_FULL_V4;
+			sdev->sd_tx_cksum |= HCKSUM_INET_PARTIAL;
+		} else {
 			return (EINVAL);
-	default:
-		break;
+		}
+
+		return (0);
+	} else if (strcmp(name, SD_PROP_TX_IP_CKSUM) == 0) {
+		if (val == NULL)
+			return (EINVAL);
+
+		if (strcmp(val, "off") == 0) {
+			sdev->sd_tx_cksum &= ~HCKSUM_IPHDRCKSUM;
+		} else if (strcmp(val, "on") == 0) {
+			sdev->sd_tx_cksum |= HCKSUM_IPHDRCKSUM;
+		} else {
+			return (EINVAL);
+		}
+
+		return (0);
+	} else if (strcmp(name, SD_PROP_LSO) == 0) {
+		if (val == NULL)
+			return (EINVAL);
+
+		if (strcmp(val, "off") == 0) {
+			sdev->sd_lso = B_FALSE;
+		} else if (strcmp(val, "on") == 0) {
+			sdev->sd_lso = B_TRUE;
+		} else {
+			return (EINVAL);
+		}
+
+		return (0);
 	}
 
-	if (sdev->sd_type == DL_ETHER)
-		return (ENOTSUP);
+	return (ENOTSUP);
+}
+
+static int
+simnet_setprop_wifi(simnet_dev_t *sdev, const char *name,
+    const mac_prop_id_t num, const uint_t len, const void *val)
+{
+	int err = 0;
+	simnet_wifidev_t *wdev = sdev->sd_wifidev;
 
-	/* mac_prop_id */
-	switch (wldp_pr_num) {
+	switch (num) {
 	case MAC_PROP_WL_ESSID: {
 		int i;
 		wl_ess_conf_t *wls;
 
-		(void) memcpy(&wdev->swd_essid, wldp_buf,
-		    sizeof (wl_essid_t));
+		(void) memcpy(&wdev->swd_essid, val, sizeof (wl_essid_t));
 		wdev->swd_linkstatus = WL_CONNECTED;
 
 		/* Lookup the signal strength of the connected ESSID */
@@ -1205,8 +1307,7 @@ simnet_m_setprop(void *arg, const char *pr_name, mac_prop_id_t wldp_pr_num,
 		break;
 	}
 	case MAC_PROP_WL_BSSID: {
-		(void) memcpy(&wdev->swd_bssid, wldp_buf,
-		    sizeof (wl_bssid_t));
+		(void) memcpy(&wdev->swd_bssid, val, sizeof (wl_bssid_t));
 		break;
 	}
 	case MAC_PROP_WL_PHY_CONFIG:
@@ -1217,10 +1318,10 @@ simnet_m_setprop(void *arg, const char *pr_name, mac_prop_id_t wldp_pr_num,
 	case MAC_PROP_WL_DESIRED_RATES:
 		break;
 	case MAC_PROP_PRIVATE:
-		err = simnet_set_priv_prop(sdev, pr_name,
-		    wldp_length, wldp_buf);
+		err = simnet_set_priv_prop_wifi(sdev, name, len, val);
 		break;
 	default:
+		err = EINVAL;
 		break;
 	}
 
@@ -1228,66 +1329,147 @@ simnet_m_setprop(void *arg, const char *pr_name, mac_prop_id_t wldp_pr_num,
 }
 
 static int
-simnet_get_priv_prop(simnet_dev_t *sdev, const char *pr_name,
-    uint_t pr_valsize, void *pr_val)
+simnet_setprop_ether(simnet_dev_t *sdev, const char *name,
+    const mac_prop_id_t num, const uint_t len, const void *val)
 {
-	simnet_wifidev_t *wdev = sdev->sd_wifidev;
 	int err = 0;
-	int value;
 
-	if (strcmp(pr_name, "_wl_esslist") == 0) {
-		/* Returns num of _wl_ess_conf_t that have been set */
-		value = wdev->swd_esslist_num;
-	} else if (strcmp(pr_name, "_wl_connected") == 0) {
-		value = ((wdev->swd_linkstatus == WL_CONNECTED) ? 1:0);
-	} else {
-		err = ENOTSUP;
+	switch (num) {
+	case MAC_PROP_PRIVATE:
+		err = simnet_set_priv_prop_ether(sdev, name, len, val);
+		break;
+	default:
+		err = EINVAL;
+		break;
 	}
 
-	if (err == 0)
-		(void) snprintf(pr_val, pr_valsize, "%d", value);
 	return (err);
 }
 
 static int
-simnet_m_getprop(void *arg, const char *pr_name, mac_prop_id_t wldp_pr_num,
-    uint_t wldp_length, void *wldp_buf)
+simnet_m_setprop(void *arg, const char *name, mac_prop_id_t num,
+    const uint_t len, const void *val)
 {
 	simnet_dev_t *sdev = arg;
-	simnet_wifidev_t *wdev = sdev->sd_wifidev;
 	int err = 0;
-	int i;
+	uint32_t mtu;
 
-	if (sdev->sd_type == DL_ETHER)
+	switch (num) {
+	case MAC_PROP_MTU:
+		(void) memcpy(&mtu, val, sizeof (mtu));
+		if (mtu > ETHERMIN && mtu < SIMNET_MAX_MTU)
+			return (mac_maxsdu_update(sdev->sd_mh, mtu));
+		else
+			return (EINVAL);
+	default:
+		break;
+	}
+
+	switch (sdev->sd_type) {
+	case DL_ETHER:
+		err = simnet_setprop_ether(sdev, name, num, len, val);
+		break;
+	case DL_WIFI:
+		err = simnet_setprop_wifi(sdev, name, num, len, val);
+		break;
+	default:
+		err = EINVAL;
+		break;
+	}
+
+	return (err);
+}
+
+static int
+simnet_get_priv_prop_wifi(const simnet_dev_t *sdev, const char *name,
+    const uint_t len, void *val)
+{
+	simnet_wifidev_t *wdev = sdev->sd_wifidev;
+	int ret, value;
+
+	if (strcmp(name, "_wl_esslist") == 0) {
+		/* Returns num of _wl_ess_conf_t that have been set */
+		value = wdev->swd_esslist_num;
+	} else if (strcmp(name, "_wl_connected") == 0) {
+		value = ((wdev->swd_linkstatus == WL_CONNECTED) ? 1:0);
+	} else {
 		return (ENOTSUP);
+	}
+
+	ret = snprintf(val, len, "%d", value);
 
-	/* mac_prop_id */
-	switch (wldp_pr_num) {
+	if (ret < 0 || ret >= len)
+		return (EOVERFLOW);
+
+	return (0);
+}
+
+static int
+simnet_get_priv_prop_ether(const simnet_dev_t *sdev, const char *name,
+    const uint_t len, void *val)
+{
+	int ret;
+	char *value;
+
+	if (strcmp(name, SD_PROP_TX_ULP_CKSUM) == 0) {
+		if ((sdev->sd_tx_cksum & HCKSUM_INET_FULL_V4) != 0) {
+			value = "fullv4";
+		} else if ((sdev->sd_tx_cksum & HCKSUM_INET_PARTIAL) != 0) {
+			value = "partial";
+		} else {
+			value = "none";
+		}
+	} else if (strcmp(name, SD_PROP_TX_IP_CKSUM) == 0) {
+		if ((sdev->sd_tx_cksum & HCKSUM_IPHDRCKSUM) != 0) {
+			value = "on";
+		} else {
+			value = "off";
+		}
+	} else if (strcmp(name, SD_PROP_LSO) == 0) {
+		value = sdev->sd_lso ? "on" : "off";
+	} else {
+		return (ENOTSUP);
+	}
+
+	ret = snprintf(val, len, "%s", value);
+
+	if (ret < 0 || ret >= len) {
+		return (EOVERFLOW);
+	}
+
+	return (0);
+}
+
+static int
+simnet_getprop_wifi(const simnet_dev_t *sdev, const char *name,
+    const mac_prop_id_t num, const uint_t len, void *val)
+{
+	const simnet_wifidev_t *wdev = sdev->sd_wifidev;
+	int err = 0;
+
+	switch (num) {
 	case MAC_PROP_WL_ESSID:
-		(void) memcpy(wldp_buf, &wdev->swd_essid,
-		    sizeof (wl_essid_t));
+		(void) memcpy(val, &wdev->swd_essid, sizeof (wl_essid_t));
 		break;
 	case MAC_PROP_WL_BSSID:
-		(void) memcpy(wldp_buf, &wdev->swd_bssid,
-		    sizeof (wl_bssid_t));
+		(void) memcpy(val, &wdev->swd_bssid, sizeof (wl_bssid_t));
 		break;
 	case MAC_PROP_WL_PHY_CONFIG:
 	case MAC_PROP_WL_AUTH_MODE:
 	case MAC_PROP_WL_ENCRYPTION:
 		break;
 	case MAC_PROP_WL_LINKSTATUS:
-		(void) memcpy(wldp_buf, &wdev->swd_linkstatus,
+		(void) memcpy(val, &wdev->swd_linkstatus,
 		    sizeof (wdev->swd_linkstatus));
 		break;
 	case MAC_PROP_WL_ESS_LIST: {
 		wl_ess_conf_t *w_ess_conf;
 
-		((wl_ess_list_t *)wldp_buf)->wl_ess_list_num =
-		    wdev->swd_esslist_num;
+		((wl_ess_list_t *)val)->wl_ess_list_num = wdev->swd_esslist_num;
 		/* LINTED E_BAD_PTR_CAST_ALIGN */
-		w_ess_conf = (wl_ess_conf_t *)((char *)wldp_buf +
+		w_ess_conf = (wl_ess_conf_t *)((char *)val +
 		    offsetof(wl_ess_list_t, wl_ess_list_ess));
-		for (i = 0; i < wdev->swd_esslist_num; i++) {
+		for (uint_t i = 0; i < wdev->swd_esslist_num; i++) {
 			(void) memcpy(w_ess_conf, wdev->swd_esslist[i],
 			    sizeof (wl_ess_conf_t));
 			w_ess_conf++;
@@ -1295,18 +1477,17 @@ simnet_m_getprop(void *arg, const char *pr_name, mac_prop_id_t wldp_pr_num,
 		break;
 	}
 	case MAC_PROP_WL_RSSI:
-		*(wl_rssi_t *)wldp_buf = wdev->swd_rssi;
+		*(wl_rssi_t *)val = wdev->swd_rssi;
 		break;
 	case MAC_PROP_WL_RADIO:
-		*(wl_radio_t *)wldp_buf = B_TRUE;
+		*(wl_radio_t *)val = B_TRUE;
 		break;
 	case MAC_PROP_WL_POWER_MODE:
 		break;
 	case MAC_PROP_WL_DESIRED_RATES:
 		break;
 	case MAC_PROP_PRIVATE:
-		err = simnet_get_priv_prop(sdev, pr_name, wldp_length,
-		    wldp_buf);
+		err = simnet_get_priv_prop_wifi(sdev, name, len, val);
 		break;
 	default:
 		err = ENOTSUP;
@@ -1316,14 +1497,54 @@ simnet_m_getprop(void *arg, const char *pr_name, mac_prop_id_t wldp_pr_num,
 	return (err);
 }
 
+static int
+simnet_getprop_ether(const simnet_dev_t *sdev, const char *name,
+    const mac_prop_id_t num, const uint_t len, void *val)
+{
+	int err = 0;
+
+	switch (num) {
+	case MAC_PROP_PRIVATE:
+		err = simnet_get_priv_prop_ether(sdev, name, len, val);
+		break;
+	default:
+		err = ENOTSUP;
+		break;
+	}
+
+	return (err);
+}
+
+static int
+simnet_m_getprop(void *arg, const char *name, const mac_prop_id_t num,
+    const uint_t len, void *val)
+{
+	const simnet_dev_t *sdev = arg;
+	int err = 0;
+
+	switch (sdev->sd_type) {
+	case DL_ETHER:
+		err = simnet_getprop_ether(sdev, name, num, len, val);
+		break;
+	case DL_WIFI:
+		err = simnet_getprop_wifi(sdev, name, num, len, val);
+		break;
+	default:
+		err = EINVAL;
+		break;
+	}
+
+	return (err);
+}
+
 static void
-simnet_priv_propinfo(const char *pr_name, mac_prop_info_handle_t prh)
+simnet_priv_propinfo_wifi(const char *name, mac_prop_info_handle_t prh)
 {
 	char valstr[MAXNAMELEN];
 
 	bzero(valstr, sizeof (valstr));
 
-	if (strcmp(pr_name, "_wl_esslist") == 0) {
+	if (strcmp(name, "_wl_esslist") == 0) {
 		(void) snprintf(valstr, sizeof (valstr), "%d", 0);
 	}
 
@@ -1332,15 +1553,10 @@ simnet_priv_propinfo(const char *pr_name, mac_prop_info_handle_t prh)
 }
 
 static void
-simnet_m_propinfo(void *arg, const char *pr_name, mac_prop_id_t wldp_pr_num,
+simnet_propinfo_wifi(const char *name, const mac_prop_id_t num,
     mac_prop_info_handle_t prh)
 {
-	simnet_dev_t *sdev = arg;
-
-	if (sdev->sd_type == DL_ETHER)
-		return;
-
-	switch (wldp_pr_num) {
+	switch (num) {
 	case MAC_PROP_WL_BSSTYPE:
 	case MAC_PROP_WL_ESS_LIST:
 	case MAC_PROP_WL_SUPPORTED_RATES:
@@ -1348,7 +1564,53 @@ simnet_m_propinfo(void *arg, const char *pr_name, mac_prop_id_t wldp_pr_num,
 		mac_prop_info_set_perm(prh, MAC_PROP_PERM_READ);
 		break;
 	case MAC_PROP_PRIVATE:
-		simnet_priv_propinfo(pr_name, prh);
+		simnet_priv_propinfo_wifi(name, prh);
+		break;
+	}
+}
+
+static void
+simnet_priv_propinfo_ether(const char *name, mac_prop_info_handle_t prh)
+{
+	if (strcmp(name, SD_PROP_TX_ULP_CKSUM) == 0 ||
+	    strcmp(name, SD_PROP_TX_IP_CKSUM) == 0 ||
+	    strcmp(name, SD_PROP_LSO) == 0) {
+		mac_prop_info_set_perm(prh, MAC_PROP_PERM_RW);
+	}
+
+	if (strcmp(name, SD_PROP_TX_ULP_CKSUM) == 0) {
+		mac_prop_info_set_default_str(prh, "none");
+	}
+
+	if (strcmp(name, SD_PROP_TX_IP_CKSUM) == 0 ||
+	    strcmp(name, SD_PROP_LSO) == 0) {
+		mac_prop_info_set_default_str(prh, "off");
+	}
+}
+
+static void
+simnet_propinfo_ether(const char *name, const mac_prop_id_t num,
+    mac_prop_info_handle_t prh)
+{
+	switch (num) {
+	case MAC_PROP_PRIVATE:
+		simnet_priv_propinfo_ether(name, prh);
+		break;
+	}
+}
+
+static void
+simnet_m_propinfo(void *arg, const char *name, const mac_prop_id_t num,
+    const mac_prop_info_handle_t prh)
+{
+	simnet_dev_t *sdev = arg;
+
+	switch (sdev->sd_type) {
+	case DL_ETHER:
+		simnet_propinfo_ether(name, num, prh);
+		break;
+	case DL_WIFI:
+		simnet_propinfo_wifi(name, num, prh);
 		break;
 	}
 }
diff --git a/usr/src/uts/common/io/simnet/simnet_impl.h b/usr/src/uts/common/io/simnet/simnet_impl.h
index 74dcba5113..659cb10d9b 100644
--- a/usr/src/uts/common/io/simnet/simnet_impl.h
+++ b/usr/src/uts/common/io/simnet/simnet_impl.h
@@ -21,6 +21,7 @@
 /*
  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
+ * Copyright 2019 Joyent, Inc.
  */
 
 #ifndef	_SYS_SIMNET_IMPL_H
@@ -84,13 +85,23 @@ typedef struct simnet_dev {
 	uint_t			sd_mac_len;
 	uchar_t			sd_mac_addr[MAXMACADDRLEN];
 	simnet_stats_t		sd_stats;
+
+	/* Capabilities */
+	uint_t			sd_tx_cksum;
+	boolean_t		sd_lso;
 } simnet_dev_t;
 
+/* Simnet dladm private properties. */
+#define	SD_PROP_TX_ULP_CKSUM	"_tx_ulp_cksum"
+#define	SD_PROP_TX_IP_CKSUM	"_tx_ipv4_cksum"
+#define	SD_PROP_LSO		"_lso"
+
 /* Simnet device flags */
 #define	SDF_SHUTDOWN	0x00000001	/* Device shutdown, no new ops */
 #define	SDF_STARTED	0x00000002	/* Device started, allow ops */
 
 #define	SIMNET_MAX_MTU	9000		/* Max MTU supported by simnet driver */
+#define	SD_LSO_MAXLEN	65535		/* Max LSO supported by simnet driver */
 
 #ifdef	__cplusplus
 }
diff --git a/usr/src/uts/common/os/ip_cksum.c b/usr/src/uts/common/os/ip_cksum.c
index 1fa1c9425b..0a237e86ec 100644
--- a/usr/src/uts/common/os/ip_cksum.c
+++ b/usr/src/uts/common/os/ip_cksum.c
@@ -21,6 +21,7 @@
 /*
  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
+ * Copyright 2019 Joyent, Inc.
  */
 /* Copyright (c) 1990 Mentat Inc. */
 
@@ -34,6 +35,7 @@
 #include <sys/vtrace.h>
 #include <inet/sctp_crc32.h>
 #include <inet/ip.h>
+#include <inet/ip6.h>
 
 #include <sys/multidata.h>
 #include <sys/multidata_impl.h>
@@ -556,3 +558,109 @@ ip_csum_hdr(ipha_t *ipha)
 		sum = 0;
 	return ((uint16_t)sum);
 }
+
+/*
+ * This function takes an mblk and IPv6 header as input and returns
+ * three pieces of information.
+ *
+ * 'hdr_length_ptr': The IPv6 header length including extension headers.
+ *
+ * 'nethdrpp': A pointer to the "next hedader" value, aka the
+ *             transport header. This argument may be set to NULL if
+ *             only the length is desired.
+ *
+ * return: Whether or not the header was malformed.
+ *
+ * This function assumes the IPv6 header along with all extensions are
+ * contained solely in this mblk: i.e., there is no b_cont walking.
+ */
+boolean_t
+ip_hdr_length_nexthdr_v6(mblk_t *mp, ip6_t *ip6h, uint16_t *hdr_length_ptr,
+    uint8_t **nexthdrpp)
+{
+	uint16_t length;
+	uint_t	ehdrlen;
+	uint8_t	*nexthdrp;
+	uint8_t *whereptr;
+	uint8_t *endptr;
+	ip6_dest_t *desthdr;
+	ip6_rthdr_t *rthdr;
+	ip6_frag_t *fraghdr;
+
+	ASSERT(IPH_HDR_VERSION(ip6h) == IPV6_VERSION);
+	length = IPV6_HDR_LEN;
+	whereptr = ((uint8_t *)&ip6h[1]); /* point to next hdr */
+	endptr = mp->b_wptr;
+
+	nexthdrp = &ip6h->ip6_nxt;
+	while (whereptr < endptr) {
+		/* Is there enough left for len + nexthdr? */
+		if (whereptr + MIN_EHDR_LEN > endptr)
+			break;
+
+		switch (*nexthdrp) {
+		case IPPROTO_HOPOPTS:
+		case IPPROTO_DSTOPTS:
+			/* Assumes the headers are identical for hbh and dst */
+			desthdr = (ip6_dest_t *)whereptr;
+			ehdrlen = 8 * (desthdr->ip6d_len + 1);
+			if ((uchar_t *)desthdr +  ehdrlen > endptr)
+				return (B_FALSE);
+			nexthdrp = &desthdr->ip6d_nxt;
+			break;
+		case IPPROTO_ROUTING:
+			rthdr = (ip6_rthdr_t *)whereptr;
+			ehdrlen =  8 * (rthdr->ip6r_len + 1);
+			if ((uchar_t *)rthdr +  ehdrlen > endptr)
+				return (B_FALSE);
+			nexthdrp = &rthdr->ip6r_nxt;
+			break;
+		case IPPROTO_FRAGMENT:
+			fraghdr = (ip6_frag_t *)whereptr;
+			ehdrlen = sizeof (ip6_frag_t);
+			if ((uchar_t *)&fraghdr[1] > endptr)
+				return (B_FALSE);
+			nexthdrp = &fraghdr->ip6f_nxt;
+			break;
+		case IPPROTO_NONE:
+			/* No next header means we're finished */
+		default:
+			*hdr_length_ptr = length;
+
+			if (nexthdrpp != NULL)
+				*nexthdrpp = nexthdrp;
+
+			return (B_TRUE);
+		}
+		length += ehdrlen;
+		whereptr += ehdrlen;
+		*hdr_length_ptr = length;
+
+		if (nexthdrpp != NULL)
+			*nexthdrpp = nexthdrp;
+	}
+	switch (*nexthdrp) {
+	case IPPROTO_HOPOPTS:
+	case IPPROTO_DSTOPTS:
+	case IPPROTO_ROUTING:
+	case IPPROTO_FRAGMENT:
+		/*
+		 * If any know extension headers are still to be processed,
+		 * the packet's malformed (or at least all the IP header(s) are
+		 * not in the same mblk - and that should never happen.
+		 */
+		return (B_FALSE);
+
+	default:
+		/*
+		 * If we get here, we know that all of the IP headers were in
+		 * the same mblk, even if the ULP header is in the next mblk.
+		 */
+		*hdr_length_ptr = length;
+
+		if (nexthdrpp != NULL)
+			*nexthdrpp = nexthdrp;
+
+		return (B_TRUE);
+	}
+}
diff --git a/usr/src/uts/common/sys/mac_impl.h b/usr/src/uts/common/sys/mac_impl.h
index ce09304699..26c535fb42 100644
--- a/usr/src/uts/common/sys/mac_impl.h
+++ b/usr/src/uts/common/sys/mac_impl.h
@@ -35,6 +35,7 @@
 #include <net/if.h>
 #include <sys/mac_flow_impl.h>
 #include <netinet/ip6.h>
+#include <sys/pattr.h>
 
 #ifdef	__cplusplus
 extern "C" {
@@ -289,54 +290,6 @@ struct mac_group_s {
 #define	GROUP_INTR_ENABLE_FUNC(g)	(g)->mrg_info.mgi_intr.mi_enable
 #define	GROUP_INTR_DISABLE_FUNC(g)	(g)->mrg_info.mgi_intr.mi_disable
 
-#define	MAC_RING_TX(mhp, rh, mp, rest) {				\
-	mac_ring_handle_t mrh = rh;					\
-	mac_impl_t *mimpl = (mac_impl_t *)mhp;				\
-	/*								\
-	 * Send packets through a selected tx ring, or through the	\
-	 * default handler if there is no selected ring.		\
-	 */								\
-	if (mrh == NULL)						\
-		mrh = mimpl->mi_default_tx_ring;			\
-	if (mrh == NULL) {						\
-		rest = mimpl->mi_tx(mimpl->mi_driver, mp);		\
-	} else {							\
-		rest = mac_hwring_tx(mrh, mp);				\
-	}								\
-}
-
-/*
- * This is the final stop before reaching the underlying driver
- * or aggregation, so this is where the bridging hook is implemented.
- * Packets that are bridged will return through mac_bridge_tx(), with
- * rh nulled out if the bridge chooses to send output on a different
- * link due to forwarding.
- */
-#define	MAC_TX(mip, rh, mp, src_mcip) {					\
-	mac_ring_handle_t	rhandle = (rh);				\
-	/*								\
-	 * If there is a bound Hybrid I/O share, send packets through	\
-	 * the default tx ring. (When there's a bound Hybrid I/O share,	\
-	 * the tx rings of this client are mapped in the guest domain	\
-	 * and not accessible from here.)				\
-	 */								\
-	_NOTE(CONSTANTCONDITION)					\
-	if ((src_mcip)->mci_state_flags & MCIS_SHARE_BOUND)		\
-		rhandle = (mip)->mi_default_tx_ring;			\
-	if (mip->mi_promisc_list != NULL)				\
-		mac_promisc_dispatch(mip, mp, src_mcip);		\
-	/*								\
-	 * Grab the proper transmit pointer and handle. Special		\
-	 * optimization: we can test mi_bridge_link itself atomically,	\
-	 * and if that indicates no bridge send packets through tx ring.\
-	 */								\
-	if (mip->mi_bridge_link == NULL) {				\
-		MAC_RING_TX(mip, rhandle, mp, mp);			\
-	} else {							\
-		mp = mac_bridge_tx(mip, rhandle, mp);			\
-	}								\
-}
-
 /* mci_tx_flag */
 #define	MCI_TX_QUIESCE	0x1
 
@@ -485,6 +438,9 @@ struct mac_impl_s {
 	mac_led_mode_t		mi_led_modes;
 	mac_capab_led_t		mi_led;
 
+	/* Cache of the Tx DB_CKSUMFLAGS that this MAC supports. */
+	uint16_t		mi_tx_cksum_flags; /* WO */
+
 	/*
 	 * MAC address and VLAN lists. SL protected.
 	 */
@@ -743,6 +699,9 @@ extern void mac_packet_print(mac_handle_t, mblk_t *);
 extern void mac_rx_deliver(void *, mac_resource_handle_t, mblk_t *,
     mac_header_info_t *);
 extern void mac_tx_notify(mac_impl_t *);
+extern mblk_t *mac_ring_tx(mac_handle_t, mac_ring_handle_t, mblk_t *);
+extern mblk_t *mac_provider_tx(mac_impl_t *, mac_ring_handle_t, mblk_t *,
+    mac_client_impl_t *);
 
 extern void mac_callback_add(mac_cb_info_t *, mac_cb_t **, mac_cb_t *);
 extern boolean_t mac_callback_remove(mac_cb_info_t *, mac_cb_t **, mac_cb_t *);