Cisco MPLS-VPN MP-BGP as-override Configuration

Cisco MPLS-VPN MP-BGP as-override Configuration

• Topology
  
  
  
  
• Configuration Settings Overview

  The following consideration is necessary because each site uses the same AS Number.

  1. as-override

     Overwrite AS No. with the first AS No. in the AS-PATH list and advertise it to the external peer.
     Normally, when self AS is included in the AS-PATH list, it is considered to be looping and the route is not valid.
     But because AS No. of the extenal peer overwrites the other AS No., its AS No. is not included in the AS-PATH list.
     

  
  
• Dynagen Config File / Router Config

  1.  Dynagen .net file
  
  2.  P1
  
  3.  P2
  
  4.  PE2
  
  5.  PE3
  
  6.  CE1
  
  7.  CEA2
  
  8.  CEB2
  
  9.  CEA3
  
  10. CEB3
  
  11. PE11
  
  12. PE12
  
  13. C1
  

• show command

  PE2(R4) :
    sh bgp vpnv4 unicast vrf VA2
  PE3(R5) :
    sh bgp vpnv4 unicast vrf VA3
  CEA2(R7) :
    sh bgp ipv4 unicast
    sh ip route
  CEA3(R9) :
    sh bgp ipv4 unicast
    sh ip route
  
  1.  PE2
  
  2.  PE3
  
  3.  CEA2
  
  4.  CEA3