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BGP route not advertised when the source interface IP address is same as next hop address

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TitleBGP route not advertised when the source interface IP address is same as next hop address
Symptoms
When BGP source interface IP address is same as destination address, then, peer switch will not learn the route through BGP
 
Environment
  • BGP
  • Summit All
  • EXOS
Cause
User-added image

If 1.1.1.1 is configured as the source-interface-address, then the loopback route 1.1.1.1 is not advertised to the peer. The route destination address is the same as BGP next hop. Such a route does not add to the forwarding table of the peer, and so it does not make sense to advertise the route to the peer.
 
SW-1
configure bgp add network 1.1.1.1/32
configure bgp neighbor 2.2.2.2 source-interface ipaddress 1.1.1.1
 
SW-2 # show bgp routes all 

Routes:
     Destination         Peer            Next-Hop        LPref Weight MED        AS-Path
----------------------------------------------------------------------------------------

Flags: (*) Preferred BGP route, (>) Active, (d) Suppressed, (h) History
       (s) Stale, (m) Multipath, (u) Unfeasible

Origin: (?) Incomplete, (e) EGP, (i) IGP

BGP Route Statistics 
  Total Rxed Routes : 0
  Feasible Routes   : 0
  Active Routes     : 0
  Rejected Routes   : 0
  Unfeasible Routes : 0
Route Statistics on Session Type 
  Routes from Int Peer: 0 
  Routes from Ext Peer: 0


 
Resolution
This is expect behavior, Change the BGP source interface ip address as other address which different from the  BGP next hop address. Then the route will be advertised through BGP.
disable bgp neighbor 2.2.2.2
configure bgp neighbor 2.2.2.2 source-interface ipaddress 11.11.11.11 
enable bgp neighbor 2.2.2.2

 
Additional notes
Related log:
 
11/23/2016 07:54:15.11 <Info:BGP.PolicyMgr.RtNotAdvertDstIPSameNH> The destination address is the same as the next hop that would be advertised. Such a route does not add to the forwarding table of the peer, and so it does not make sense to advertise the route to the peer.

 

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