[neighsync] Ignoring IPv4 link local addresses (sonic-net#2260)

* [neighsync] Ignoring IPv4 link local addresses Skipping over writing ipv4 link local neighbors to APPL_DB. This was causing link local neighbors to appear and led to long switchover times during mux state change. Signed-off-by: Nikola Dancejic <ndancejic@microsoft.com>
Ndancejic · Jun 10, 2022 · 3c134a4 · 3c134a4
1 parent eef993f
commit 3c134a4
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diff --git a/neighsyncd/neighsync.cpp b/neighsyncd/neighsync.cpp
@@ -74,7 +74,17 @@ void NeighSync::onMsg(int nlmsg_type, struct nl_object *obj)
     key+= ":";
 
     nl_addr2str(rtnl_neigh_get_dst(neigh), ipStr, MAX_ADDR_SIZE);
-    /* Ignore IPv6 link-local addresses as neighbors */
+
+    /* Ignore IPv4 link-local addresses as neighbors */
+    IpAddress ipAddress(ipStr);
+    if (family == IPV4_NAME && ipAddress.getAddrScope() == IpAddress::AddrScope::LINK_SCOPE)
+    {
+        SWSS_LOG_INFO("Link Local address received, ignoring for %s", ipStr);
+        return;
+    }
+
+
+    /* Ignore IPv6 link-local addresses as neighbors, if ipv6 link local mode is disabled */
     if (family == IPV6_NAME && IN6_IS_ADDR_LINKLOCAL(nl_addr_get_binary_addr(rtnl_neigh_get_dst(neigh))))
         return;
     /* Ignore IPv6 multicast link-local addresses as neighbors */

diff --git a/tests/test_neighbor.py b/tests/test_neighbor.py
@@ -413,6 +413,53 @@ def test_FlushResolveNeighborIpv4(self, dvs, testlog):
         (exitcode, output) = dvs.runcmd(['sh', '-c', "supervisorctl status nbrmgrd | awk '{print $2}'"])
         assert output == "RUNNING\n"
 
+    def test_Ipv4LinkLocalNeighbor(self, dvs, testlog):
+        self.setup_db(dvs)
+
+        # bring up interface
+        self.set_admin_status("Ethernet8", "up")
+
+        # create interface
+        self.create_l3_intf("Ethernet8", "")
+
+        # assign IP to interface
+        self.add_ip_address("Ethernet8", "10.0.0.1/24")
+
+        # add neighbor
+        self.add_neighbor("Ethernet8", "169.254.0.0", "00:01:02:03:04:05")
+
+        # check application database
+        tbl = swsscommon.Table(self.pdb, "NEIGH_TABLE:Ethernet8")
+        intf_entries = tbl.getKeys()
+        assert len(intf_entries) == 0
+
+        # check ASIC neighbor database
+        tbl = swsscommon.Table(self.adb, "ASIC_STATE:SAI_OBJECT_TYPE_NEIGHBOR_ENTRY")
+        intf_entries = tbl.getKeys()
+        assert len(intf_entries) == 0
+
+        # remove neighbor
+        self.remove_neighbor("Ethernet8", "169.254.0.0")
+
+        # remove IP from interface
+        self.remove_ip_address("Ethernet8", "10.0.0.1/24")
+
+        # remove interface
+        self.remove_l3_intf("Ethernet8")
+
+        # bring down interface
+        self.set_admin_status("Ethernet8", "down")
+
+        # check application database
+        tbl = swsscommon.Table(self.pdb, "NEIGH_TABLE:Ethernet8")
+        intf_entries = tbl.getKeys()
+        assert len(intf_entries) == 0
+
+        # check ASIC neighbor database
+        tbl = swsscommon.Table(self.adb, "ASIC_STATE:SAI_OBJECT_TYPE_NEIGHBOR_ENTRY")
+        intf_entries = tbl.getKeys()
+        assert len(intf_entries) == 0
+
 
 # Add Dummy always-pass test at end as workaroud
 # for issue when Flaky fail on final test it invokes module tear-down before retrying