Avoid updating the NHGroup when mux state changes. (#126)

Port PR sonic-net/sonic-swss#3822
NHGroup update is not required during mux state updates. When a mux neighbor in a ECMP NexthopGroup changes state to standby we point the prefix route originally pointing to the ECMP nexthop group to any available active neighbor NH or tunnel NH and the original ECMP nexthopgroup remains unused, so this update is useless and uncessarily takes extra SAI calls. This fix also avoid creation of nexthop group with a mix of different types of NextHops which will allow platform that do not support such nexthop groups.

Signed-off-by: Manas Kumar Mandal <[email protected]>

Author: manamand2020

orchagent/muxorch.cpp

@@ -818,27 +818,6 @@ bool MuxNbrHandler::enable(bool update_rt)
         /* Increment ref count for new NHs */
         gNeighOrch->increaseNextHopRefCount(nh_key, num_routes);
 
-        /*
-         * Invalidate current nexthop group and update with new NH
-         * Ref count update is not required for tunnel NH IDs (nh_removed)
-         */
-        uint32_t nh_removed, nh_added;
-        if (!gRouteOrch->invalidnexthopinNextHopGroup(nh_key, nh_removed))
-        {
-            SWSS_LOG_ERROR("Removing existing NH failed for %s", nh_key.ip_address.to_string().c_str());
-            return false;
-        }
-
-        if (!gRouteOrch->validnexthopinNextHopGroup(nh_key, nh_added))
-        {
-            SWSS_LOG_ERROR("Adding NH failed for %s", nh_key.ip_address.to_string().c_str());
-            return false;
-        }
-        SWSS_LOG_INFO("Adding NH for %s, nh_added: %u", nh_key.ip_address.to_string().c_str(), nh_added);
-
-        /* Increment ref count for ECMP NH members */
-        gNeighOrch->increaseNextHopRefCount(nh_key, nh_added);
-
         if (update_rt)
         {
             updateTunnelRoute(nh_key, false);
@@ -892,24 +871,6 @@ bool MuxNbrHandler::disable(sai_object_id_t tnh)
         /* Decrement ref count for old NHs */
         gNeighOrch->decreaseNextHopRefCount(nh_key, num_routes);
 
-        /* Invalidate current nexthop group and update with new NH */
-        uint32_t nh_removed, nh_added;
-        if (!gRouteOrch->invalidnexthopinNextHopGroup(nh_key, nh_removed))
-        {
-            SWSS_LOG_ERROR("Removing existing NH failed for %s", nh_key.ip_address.to_string().c_str());
-            return false;
-        }
-        SWSS_LOG_INFO("Removing existing NH for %s, nh_removed: %u", nh_key.ip_address.to_string().c_str(), nh_removed);
-
-        /* Decrement ref count for ECMP NH members */
-        gNeighOrch->decreaseNextHopRefCount(nh_key, nh_removed);
-
-        if (!gRouteOrch->validnexthopinNextHopGroup(nh_key, nh_added))
-        {
-            SWSS_LOG_ERROR("Adding NH failed for %s", nh_key.ip_address.to_string().c_str());
-            return false;
-        }
-
         updateTunnelRoute(nh_key, true);
 
         it++;