3Com Switch 8800 Advanced Software V5 Configuration Guide

436 CHAPTER 35: BGP CONFIGURATION
■ It is required to specify for a BGP router a router ID, a 32-bit unsigned integer
and the unique identifier of the router in the AS.
■ You must create a peer group before configuring basic functions for it. For
information about creating a peer group, refer to
“Configuring BGP Peer
Groups” on page 444.
■ You can specify a router ID manually. If not, the system selects an IP address as
the router ID. The selection sequence is the highest IP address among loopback
interface addresses; if not available, then the highest IP address of interfaces. It
is recommended to specify a loopback interface address as the router ID to
enhance network reliability. Only when the interface with the selected Router
ID or the manual Router ID is deleted will the system select another ID for the
router.
■ To guarantee updates sending in case of interface failure, you can specify the
source interface of updates as a loopback interface.
■ In general, direct physical links should be available between EBGP peers. If not,
you can use the peer ebgp-max-hop command to establish a TCP connection
over multiple hops between two peers. You do not need to use this command
for directly connected EBGP peers, which employ loopback interfaces for peer
relationship establishment.
Controlling Route
Distribution and
Reception
Prerequisites Before configuring this task, you have completed BGP basic configuration.
Configuring BGP Route
Redistribution
BGP can advertise the routing information of the local AS to peering ASs, but it
redistributes routing information from IGP into BGP routing table rather than
self-finding. During route redistribution, BGP can filter routing information
according to different routing protocols.
To configure BGP route redistribution, use the following commands:
To do... Use the command... Remarks
Enter system view system-view -
Enter BGP view bgp as-number -
Enable BGP to redistribute
default route into the BGP
routing table
default-route imported Optional
Not enabled by default
Redistribute routes from
another routing protocol for
advertisement
import-route protocol [
process-id [ med med-value |
route-policy
route-policy-name ] * ]
Required
Not redistributed by default
Advertise a network to the
BGP routing table
network ip-address [ mask |
mask-length ] [ short-cut |
route-policy
route-policy-name ]
Optional
Not advertised by default