Cisco Cisco IOS Software Release 12.2(14)S
BGP Next Hop Propagation
Prerequisites for BGP Next Hop Propagation
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Cisco IOS Release 12.0(16)ST, 12.2, 12.2(14)S, and 12.0(22)S
Prerequisites for BGP Next Hop Propagation
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BGP peering has been established, and the next hop is accessible.
Restrictions for BGP Next Hop Propagation
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BGP Next Hop Propagation can be configured only between multihop eBGP peers. The follow error
message will be displayed if you attempt to configure this feature for a directly connect neighbor:
message will be displayed if you attempt to configure this feature for a directly connect neighbor:
%BGP: Can propagate the nexthop only to multi-hop EBGP neighbor
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Do not use the neighbor next-hop-self command to modify the next hop attribute for a route
reflector when this feature is enabled for a route reflector client. Using the neighbor next-hop-self
command on the route reflector will modify next hop attributes only for routes that are learned from
eBGP peers and not the intended routes that are being reflected from the route reflector clients. To
modify the next hop attribute when reflecting a route, use an outbound route map.
reflector when this feature is enabled for a route reflector client. Using the neighbor next-hop-self
command on the route reflector will modify next hop attributes only for routes that are learned from
eBGP peers and not the intended routes that are being reflected from the route reflector clients. To
modify the next hop attribute when reflecting a route, use an outbound route map.
Information About Next Hop Propagation
This section contains the following concepts:
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BGP Next Hop Propagation Overview
The BGP Next Hop Propagation feature provides additional flexibility when designing and migrating
networks. The BGP Next Hop Propagation feature allows a route reflector to modify the next hop
attribute for a reflected route and allows BGP to send an update to an eBGP multihop peer with the next
hop attribute unchanged.
networks. The BGP Next Hop Propagation feature allows a route reflector to modify the next hop
attribute for a reflected route and allows BGP to send an update to an eBGP multihop peer with the next
hop attribute unchanged.
Caution
Incorrectly setting BGP attributes for a route reflector can cause inconsistent routing, routing loops,
or a loss of connectivity. Setting BGP attributes for a route reflector should be attempted only by an
experienced network operator.
or a loss of connectivity. Setting BGP attributes for a route reflector should be attempted only by an
experienced network operator.
The configuration of this feature in conjunction with the iBGP Multipath Load Sharing feature allows
you to use an outbound route map to include BGP route reflectors in the forwarding path.
you to use an outbound route map to include BGP route reflectors in the forwarding path.
Benefits of BGP Next Hop Propagation
The BGP Next Hop Propagation feature allows you to perform the following tasks:
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Bring the route reflector into the forwarding path, which can be used with the iBGP Multipath Load
Sharing feature to configure load balancing.
Sharing feature to configure load balancing.
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Configure interprovider Multiprotocol Label Switching (MPLS) Virtual Private Networks (VPNs)
by not modifying the next hop attribute when advertising routes to an eBGP peer.
by not modifying the next hop attribute when advertising routes to an eBGP peer.