Added change to add 'peerType' as element in NEIGH_STATE_TABLE. (soni…

…c-net#15265)

What I did:
Added change to add 'peerType' as element in NEIGH_STATE_TABLE.
'peerType' can be i-BGP vs e-BGP determined based on local and remote AS number.

Why I did:
This is useful to filter neighbors in SONiC as internal vs external in chassis use-case (example: telemetry)

Verification:

Manual Verification
127.0.0.1:6379[6]> hgetall "NEIGH_STATE_TABLE|10.0.0.5"
1) "state"
2) "Established"
3) "peerType"
4) "e-BGP"
127.0.0.1:6379[6]> hgetall  "NEIGH_STATE_TABLE|2603:10e2:400::4"
1) "state"
2) "Established"
3) "peerType"
4) "i-BGP"

Also sonic-mgmt test case test_bgp_fact.py is enhanced:  Enhanced bgp_fact to validate NEIGH_STATE_TABLE element 'peerType' sonic-mgmt#8462

src/sonic-bgpcfgd/bgpmon/bgpmon.py

@@ -6,7 +6,8 @@
 
     Initial creation of this daemon is to assist SNMP agent in obtaining the
     BGP related information for its MIB support. The MIB that this daemon is
-    assisting is for the CiscoBgp4MIB (Neighbor state only). If there are other
+    assisting is for the CiscoBgp4MIB (Neighbor state only). Also for chassis use-case
+    it identify if the given BGP neighbors as i-BGP vs e-BGP. If there are other
     BGP related items that needs to be updated in a periodic manner in the
     future, then more can be added into this process.
 
@@ -68,7 +69,9 @@ def update_new_peer_states(self, peer_dict):
         peer_l = peer_dict["peers"].keys()
         self.new_peer_l.update(peer_l)
         for peer in peer_l:
-            self.new_peer_state[peer] = peer_dict["peers"][peer]["state"]
+            self.new_peer_state[peer] = (peer_dict["peers"][peer]["state"], 
+                                         peer_dict["peers"][peer]["remoteAs"],
+                                         peer_dict["peers"][peer]["localAs"])
 
     # Get a new snapshot of BGP neighbors and store them in the "new" location
     def get_all_neigh_states(self):
@@ -123,17 +126,19 @@ def update_neigh_states(self):
             key = "NEIGH_STATE_TABLE|%s" % peer
             if peer in self.peer_l:
                 # only update the entry if state changed
-                if self.peer_state[peer] != self.new_peer_state[peer]:
+                if self.peer_state[peer] != self.new_peer_state[peer][0]:
                     # state changed. Update state DB for this entry
-                    state = self.new_peer_state[peer]
-                    data[key] = {'state':state}
+                    state = self.new_peer_state[peer][0]
+                    peerType = "i-BGP" if self.new_peer_state[peer][1] == self.new_peer_state[peer][2] else "e-BGP"
+                    data[key] = {'state':state, 'peerType':peerType}
                     self.peer_state[peer] = state
                 # remove this neighbor from old set since it is accounted for
                 self.peer_l.remove(peer)
             else:
                 # New neighbor found case. Add to dictionary and state DB
-                state = self.new_peer_state[peer]
-                data[key] = {'state':state}
+                state = self.new_peer_state[peer][0]
+                peerType = "i-BGP" if self.new_peer_state[peer][1] == self.new_peer_state[peer][2] else "e-BGP"
+                data[key] = {'state':state, 'peerType':peerType}
                 self.peer_state[peer] = state
             if len(data) > PIPE_BATCH_MAX_COUNT:
                 self.flush_pipe(data)