3Com Switch 8800 Family Configuration Guide

548 CHAPTER 49: BGP/MPLS VPN CONFIGURATION
Perform the following configuration in IPv4 instance sub-address family view.
By default, the received route update information is not allowed to generate loop
information.
Step 7: Configure BGP features.
Configuring PE-PE route exchanging
To exchange VPN-IPv4 routing information between PEs, you should configure
MP-IBGP on PEs.
Perform the following configuration in BGP view or PVN instance address family
sub-view.
1 Configure IBGP
These steps are often required.
Step 1: Configure BGP as asynchronous.
Step 2: Configure BGP neighbor.
Note that BGP adjacency is established through Loopback interface and the
sub-net mask must be 32 bits.
Step 3: Permit BGP session over any operable TCP interface.
In general, BGP uses the best local address in TCP connection. To keep TCP
connection available even when the interface involved fails, you can perform the
following configuration to permit BGP session over any interface through which
TCP connection with the peer can be set up. The command here is usually
executed together with the Loopback interface.
Perform the following configuration in VPNv4 sub-address family view.
BGP creates BGP adjacency to the peer end using specific interfaces, which is
usually the loopback interface. Because this interface is always in the up state,
thus it reduces the strike brought by network shock.
Tabl e 545 Configure to allow/disable routing loop
Operation Command
Configure to allow routing loop
peer { group-name | peer-address }
allow-as-loop asn-limit
Configure to disable routing loop
undo peer { group-name | peer-address }
allow-as-loop asn-limit
Tabl e 546 Permit BGP session over any operable TCP interface
Operation Command
Permit BGP session over any
operable TCP interface
peer { peer-address | group-name } connect-interface {
interface-type interface-number }
Use the best local address for
TCP connection
undo peer { peer-address | group-name }
connect-interface