3Com S7902E, Configuration Manual

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Since a router can reside in only one AS, the router can run only one BGP process.
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You need to create a peer group before configuring it.
Specifying the Source Interface for TCP Connections
BGP uses TCP as the transport layer protocol. By default, BGP uses the output interface of the optimal
router to a peer as the source interface for establishing TCP connections to the peer. If a BGP router
has multiple links to a peer, when the source interface fails, BGP has to reestablish TCP connections,
causing network oscillation. Therefore, it is recommended to use a loopback interface as the source
interface to enhance stability of BGP connections.
Follow these steps to specify the source interface of TCP connections:
To do… Use the command… Remarks
Enter system view system-view
—
Enter BGP view bgp as-number
—
Specify the source interface for
establishing TCP connections
to a peer or peer group
peer { group-name |
ip-address }
connect-interface
interface-type
interface-number
Required
By default, BGP uses the
outbound interface of the best
route to the BGP peer/peer group
as the source interface for
establishing a TCP connection to
the peer/peer group.
To establish multiple BGP connections between two routers, you need to specify on the local router the
source interface for establishing TCP connections to each peer; otherwise, the local BGP router may
fail to establish TCP connections to a peer when using the outbound interface of the best route to the
peer as the source interface.
Allowing Establishment of eBGP Connection to a Non Directly Connected Peer/Peer
Group
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.
Follow these steps to allow establishment of eBGP connection to a non directly connected peer/peer
group:
To do… Use the command… Remarks
Enter system view system-view
—
Enter BGP view bgp as-number
—