diff --git a/tests/automake.mk b/tests/automake.mk
index bdf6828..0a4e9e6 100644
--- a/tests/automake.mk
+++ b/tests/automake.mk
@@ -106,7 +106,8 @@ SYSTEM_USERSPACE_TESTSUITE_AT = \
 
 SYSTEM_TESTSUITE_AT = \
 	tests/system-common-macros.at \
-	tests/system-traffic.at
+	tests/system-traffic.at \
+	tests/system-ovn.at
 
 TESTSUITE = $(srcdir)/tests/testsuite
 TESTSUITE_PATCH = $(srcdir)/tests/testsuite.patch
diff --git a/tests/system-kmod-testsuite.at b/tests/system-kmod-testsuite.at
index fc71a48..bdf57c8 100644
--- a/tests/system-kmod-testsuite.at
+++ b/tests/system-kmod-testsuite.at
@@ -23,3 +23,4 @@ m4_include([tests/system-common-macros.at])
 m4_include([tests/system-kmod-macros.at])
 
 m4_include([tests/system-traffic.at])
+m4_include([tests/system-ovn.at])
diff --git a/tests/system-ovn.at b/tests/system-ovn.at
new file mode 100644
index 0000000..b58a5b7
--- /dev/null
+++ b/tests/system-ovn.at
@@ -0,0 +1,141 @@
+AT_SETUP([ovn -- 2 LRs connected via LS, gateway router, NAT])
+AT_KEYWORDS([ovnnat])
+ovn_start
+
+OVS_TRAFFIC_VSWITCHD_START()
+ADD_BR([br-int])
+
+# Set external-ids in br-int needed for ovn-controller
+ovs-vsctl \
+        -- set Open_vSwitch . external-ids:system-id=hv1 \
+        -- set Open_vSwitch . external-ids:ovn-remote=unix:$ovs_base/ovn-sb/ovn-sb.sock \
+        -- set Open_vSwitch . external-ids:ovn-encap-type=geneve \
+        -- set Open_vSwitch . external-ids:ovn-encap-ip=169.0.0.1 \
+        -- set bridge br-int fail-mode=secure other-config:disable-in-band=true
+
+# Start ovn-controller
+start_daemon ovn-controller
+
+# Logical network:
+# Two LRs - R1 and R2 that are connected to each other via LS "join"
+# in 20.0.0.0/24 network. R1 has switchess foo (192.168.1.0/24) and
+# bar (192.168.2.0/24) connected to it. R2 has alice (172.16.1.0/24) connected
+# to it.  R2 is a gateway router on which we add NAT rules.
+
+ovn-nbctl create Logical_Router name=R1
+ovn-nbctl create Logical_Router name=R2 options:chassis=hv1
+
+ovn-nbctl ls-add foo
+ovn-nbctl ls-add bar
+ovn-nbctl ls-add alice
+ovn-nbctl ls-add join
+
+# Connect foo to R1
+ovn-nbctl lrp-add R1 foo 00:00:01:01:02:03 192.168.1.1/24
+ovn-nbctl lsp-add foo rp-foo -- set Logical_Switch_Port rp-foo \
+    type=router options:router-port=foo addresses=\"00:00:01:01:02:03\"
+
+# Connect bar to R1
+ovn-nbctl lrp-add R1 bar 00:00:01:01:02:04 192.168.2.1/24
+ovn-nbctl lsp-add bar rp-bar -- set Logical_Switch_Port rp-bar \
+    type=router options:router-port=bar addresses=\"00:00:01:01:02:04\"
+
+# Connect alice to R2
+ovn-nbctl lrp-add R2 alice 00:00:02:01:02:03 172.16.1.1/24
+ovn-nbctl lsp-add alice rp-alice -- set Logical_Switch_Port rp-alice \
+    type=router options:router-port=alice addresses=\"00:00:02:01:02:03\"
+
+# Connect R1 to join
+ovn-nbctl lrp-add R1 R1_join 00:00:04:01:02:03 20.0.0.1/24
+ovn-nbctl lsp-add join r1-join -- set Logical_Switch_Port r1-join \
+    type=router options:router-port=R1_join addresses='"00:00:04:01:02:03"'
+
+# Connect R2 to join
+ovn-nbctl lrp-add R2 R2_join 00:00:04:01:02:04 20.0.0.2/24
+ovn-nbctl lsp-add join r2-join -- set Logical_Switch_Port r2-join \
+    type=router options:router-port=R2_join addresses='"00:00:04:01:02:04"'
+
+# Static routes.
+ovn-nbctl lr-route-add R1 172.16.1.0/24 20.0.0.2
+ovn-nbctl lr-route-add R2 192.168.0.0/16 20.0.0.1
+
+# Logical port 'foo1' in switch 'foo'.
+ADD_NAMESPACES(foo1)
+ADD_VETH(foo1, foo1, br-int, "192.168.1.2/24", "f0:00:00:01:02:03", \
+         "192.168.1.1")
+ovn-nbctl lsp-add foo foo1 \
+-- lsp-set-addresses foo1 "f0:00:00:01:02:03 192.168.1.2"
+
+# Logical port 'alice1' in switch 'alice'.
+ADD_NAMESPACES(alice1)
+ADD_VETH(alice1, alice1, br-int, "172.16.1.2/24", "f0:00:00:01:02:04", \
+         "172.16.1.1")
+ovn-nbctl lsp-add alice alice1 \
+-- lsp-set-addresses alice1 "f0:00:00:01:02:04 172.16.1.2"
+
+# Logical port 'bar1' in switch 'bar'.
+ADD_NAMESPACES(bar1)
+ADD_VETH(bar1, bar1, br-int, "192.168.2.2/24", "f0:00:00:01:02:05", \
+"192.168.2.1")
+ovn-nbctl lsp-add bar bar1 \
+-- lsp-set-addresses bar1 "f0:00:00:01:02:05 192.168.2.2"
+
+# Add a DNAT rule.
+ovn-nbctl -- --id=@nat create nat type="dnat" logical_ip=192.168.1.2 \
+    external_ip=30.0.0.2 -- add logical_router R2 nat @nat
+
+# Add a SNAT rule
+ovn-nbctl -- --id=@nat create nat type="snat" logical_ip=192.168.2.2 \
+    external_ip=30.0.0.1 -- add logical_router R2 nat @nat
+
+# wait for ovn-controller to catch up.
+sleep 2
+
+# 'alice1' should be able to ping 'foo1' directly.
+NS_CHECK_EXEC([alice1], [ping -q -c 3 -i 0.3 -w 2 192.168.1.2 | FORMAT_PING], \
+[0], [dnl
+3 packets transmitted, 3 received, 0% packet loss, time 0ms
+])
+
+# North-South DNAT: 'alice1' should also be able to ping 'foo1' via 30.0.0.2
+NS_CHECK_EXEC([alice1], [ping -q -c 3 -i 0.3 -w 2 192.168.1.2 | FORMAT_PING], \
+[0], [dnl
+3 packets transmitted, 3 received, 0% packet loss, time 0ms
+])
+
+# South-North SNAT: 'bar1' pings 'alice1'. But 'alice1' receives traffic
+# from 30.0.0.1
+NS_CHECK_EXEC([bar1], [ping -q -c 3 -i 0.3 -w 2 172.16.1.2 | FORMAT_PING], \
+[0], [dnl
+3 packets transmitted, 3 received, 0% packet loss, time 0ms
+])
+
+# We verify that SNAT indeed happened via 'dump-conntrack' command.
+AT_CHECK([ovs-appctl dpctl/dump-conntrack | FORMAT_CT(30.0.0.1) | \
+sed -e 's/zone=[[0-9]]*/zone=<cleared>/'], [0], [dnl
+icmp,orig=(src=192.168.2.2,dst=172.16.1.2,id=<cleared>),reply=(src=172.16.1.2,dst=30.0.0.1,id=<cleared>),zone=<cleared>
+])
+
+# Add static routes to handle east-west NAT.
+ovn-nbctl lr-route-add R1 30.0.0.0/24 20.0.0.2
+
+# East-west DNAT and SNAT: 'bar1' pings 30.0.0.2. 'foo1' receives it.
+NS_CHECK_EXEC([bar1], [ping -q -c 3 -i 0.3 -w 2 30.0.0.2 | FORMAT_PING], \
+[0], [dnl
+3 packets transmitted, 3 received, 0% packet loss, time 0ms
+])
+
+OVS_APP_EXIT_AND_WAIT([ovn-controller])
+
+as ovn-sb
+OVS_APP_EXIT_AND_WAIT([ovsdb-server])
+
+as ovn-nb
+OVS_APP_EXIT_AND_WAIT([ovsdb-server])
+
+as northd
+OVS_APP_EXIT_AND_WAIT([ovn-northd])
+
+as
+OVS_TRAFFIC_VSWITCHD_STOP(["/failed to query port patch-.*/d"])
+AT_CLEANUP
