Inter-AS Option C with Route Reflectors

When the BGP/MPLS VPN peer is a route reflector (Figure 80), issue the neighbor next-hop-unchanged command to prevent the RR from rewriting the BGP next-hop attribute when the RR advertises routes to external neighbors. Issuing this command causes the VPN RR that is multihop peering with another RR in the AS to send the next hop unchanged for the VPN routes that it advertises.

Figure 80: Topology for Inter-AS Option C with Route Reflectors

neighbor next-hop-unchanged

• Use to prevent BGP from modifying the next hop sent to the BGP peer.
• Outbound route maps take precedence over this command, enabling prefixes that match the route map to be modified, regardless of this command.
• Takes effect immediately.
• Example

  host1:vr1(config-router-af)#neighbor next-hop-unchanged 10.24.15.32

• Issuing this command automatically removes the neighbor next-hop-self configuration (enabled or disabled) on the peer or peer group. Issuing the no or default version of this command has no effect on the neighbor next-hop-self configuration.
• Use the no version to reenable BGP to modify the next hop.
• See neighbor next-hop-unchanged.

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