[ovs-dev] [PATCH OVN] Add "disable_arp_nd_rsp" option to LSP

[Naveen Yerramneni]

This option can be used to enable/disable arp/nd reply flows.

Usecase:
=========
It is useful to reduce packet loss when VM is being migrated to
different AZ via VXLAN tunnel. Port is configured in both AZs
on different logical switches which are sharing same IP subnet.
In reality, the port is active on only one logical switch.
Skipping ARP/ND responder and letting the ARP/ND get flooded to
learn the location of the port.

Signed-off-by: Naveen Yerramneni <naveen.yerramn...@nutanix.com>
---
 northd/northd.c     | 10 +++++++++-
 tests/ovn-northd.at | 31 +++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/northd/northd.c b/northd/northd.c
index 952f8200d..4e070c0fe 100644
--- a/northd/northd.c
+++ b/northd/northd.c
@@ -1844,6 +1844,12 @@ localnet_can_learn_mac(const struct 
nbrec_logical_switch_port *nbsp)
     return smap_get_bool(&nbsp->options, "localnet_learn_fdb", false);
 }
 
+static bool
+lsp_disable_arp_nd_rsp(const struct nbrec_logical_switch_port *nbsp)
+{
+    return smap_get_bool(&nbsp->options, "disable_arp_nd_rsp", false);
+}
+
 static bool
 lsp_is_type_changed(const struct sbrec_port_binding *sb,
                 const struct nbrec_logical_switch_port *nbsp,
@@ -9921,7 +9927,9 @@ build_lswitch_arp_nd_responder_known_ips(struct ovn_port 
*op,
             return;
         }
 
-        if (lsp_is_external(op->nbsp) || op->has_unknown) {
+        if (lsp_is_external(op->nbsp) || op->has_unknown ||
+           (!strcmp(op->nbsp->type, "") &&
+            lsp_disable_arp_nd_rsp(op->nbsp))) {
             return;
         }
 
diff --git a/tests/ovn-northd.at b/tests/ovn-northd.at
index 9a0d418e4..9a36ee810 100644
--- a/tests/ovn-northd.at
+++ b/tests/ovn-northd.at
@@ -11094,5 +11094,36 @@ AT_CHECK([ovn-sbctl dump-flows S1 | grep pre_acl | sed 
's/table=./table=?/'], [0
 ])
 
 
+AT_CLEANUP
+])
+
+OVN_FOR_EACH_NORTHD_NO_HV([
+AT_SETUP([check options:disable_arp_nd_rsp for LSP])
+ovn_start NORTHD_TYPE
+ovn-nbctl ls-add S1
+ovn-nbctl --wait=sb lsp-add S1 S1-vm1
+ovn-nbctl --wait=sb lsp-set-addresses S1-vm1 "50:54:00:00:00:010 192.168.0.10 
fd00::10"
+
+ovn-sbctl dump-flows S1 > S1flows
+AT_CAPTURE_FILE([S1flows])
+
+AT_CHECK([grep -e "ls_in_arp_rsp" S1flows | sed 's/table=../table=??/'], [0], 
[dnl
+  table=??(ls_in_arp_rsp      ), priority=100  , match=(arp.tpa == 
192.168.0.10 && arp.op == 1 && inport == "S1-vm1"), action=(next;)
+  table=??(ls_in_arp_rsp      ), priority=100  , match=(nd_ns && ip6.dst == 
{fd00::10, ff02::1:ff00:10} && nd.target == fd00::10 && inport == "S1-vm1"), 
action=(next;)
+  table=??(ls_in_arp_rsp      ), priority=50   , match=(arp.tpa == 
192.168.0.10 && arp.op == 1), action=(eth.dst = eth.src; eth.src = 
50:54:00:00:00:10; arp.op = 2; /* ARP reply */ arp.tha = arp.sha; arp.sha = 
50:54:00:00:00:10; arp.tpa = arp.spa; arp.spa = 192.168.0.10; outport = inport; 
flags.loopback = 1; output;)
+  table=??(ls_in_arp_rsp      ), priority=50   , match=(nd_ns && ip6.dst == 
{fd00::10, ff02::1:ff00:10} && nd.target == fd00::10), action=(nd_na { eth.src 
= 50:54:00:00:00:10; ip6.src = fd00::10; nd.target = fd00::10; nd.tll = 
50:54:00:00:00:10; outport = inport; flags.loopback = 1; output; };)
+  table=??(ls_in_arp_rsp      ), priority=0    , match=(1), action=(next;)
+])
+
+#Set the disable_arp_nd_rsp option and verify the flow
+ovn-nbctl --wait=sb set logical_switch_port S1-vm1 
options:disable_arp_nd_rsp=true
+
+ovn-sbctl dump-flows S1 > S1flows
+AT_CAPTURE_FILE([S1flows])
+
+AT_CHECK([grep -e "ls_in_arp_rsp" S1flows | sed 's/table=../table=??/'], [0], 
[dnl
+  table=??(ls_in_arp_rsp      ), priority=0    , match=(1), action=(next;)
+])
+
 AT_CLEANUP
 ])
-- 
2.36.6

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