Limit the number of ECMP paths to 128.

While processing received nexthops from control node, limit the number
to 128. Also, calculate the ksync buffer length based on number of components
in the composite NH.

Change-Id: I58e3d297d5f719ed1be245c6021c579bba3a9ea3
closes-bug: #1664896
(cherry picked from commit b3196b2)

src/vnsw/agent/controller/controller_peer.cc

@@ -674,6 +674,16 @@ void AgentXmppChannel::AddEcmpRoute(string vrf_name, IpAddress prefix_addr,
             continue;
         }
 
+        if (comp_nh_list.size() >= maximum_ecmp_paths) {
+            std::stringstream msg;
+            msg << "Nexthop paths for prefix "
+                << prefix_addr.to_string() << "/" << prefix_len
+                << " (" << item->entry.next_hops.next_hop.size()
+                << ") exceed the maximum supported, ignoring them";
+            CONTROLLER_TRACE(Trace, GetBgpPeerName(), vrf_name, msg.str());
+            break;
+        }
+
         uint32_t label = item->entry.next_hops.next_hop[i].label;
         if (agent_->router_id() == addr.to_v4()) {
             //Get local list of interface and append to the list

src/vnsw/agent/controller/controller_peer.h

@@ -28,6 +28,8 @@ class EcmpLoadBalance;
 
 class AgentXmppChannel {
 public:
+    static const uint32_t maximum_ecmp_paths = 128;
+
     AgentXmppChannel(Agent *agent,
                      const std::string &xmpp_server, 
                      const std::string &label_range, uint8_t xs_idx);

src/vnsw/agent/vrouter/ksync/nexthop_ksync.h

@@ -50,10 +50,7 @@ class NHKSyncEntry : public KSyncNetlinkDBEntry {
 
     int MsgLen() {
         // for larger component NH lists, increase message length
-        if (component_nh_list_.size() < 256)
-            return kDefaultNhMsgSize;
-        else
-            return 2 * kDefaultNhMsgSize;
+        return kDefaultNhMsgSize * ((component_nh_list_.size() / 128) + 1);
     }
 private:
     class KSyncComponentNH {