3Com Switch 8800 Family Configuration Guide

BGP/MPLS VPN Configuration 547
Step 4: Configure MBGP to import VPN route of direct-connect CE
To advertise correct VPN route over public network to other PEs with which BGP
adjacency has been created, a PE must import the VPN routing information of the
direct-connect CE into its MBGP routing table.
For example, if a static route is used between PE and CE, PE must import a static
route in VPN-instance address family sub-view of MBGP (import-route static). If RIP
is run between PE and CE, PE must import an RIP route in VPN-instance view of
MBGP (import-route rip). If BGP is run between PE and CE, MBGP imports a
direct-connect route.
Perform the following configuration in VPN instance address family sub-view.
Step 5: Configure BGP as asynchronous.
Perform the following configuration in VPN instance address family sub-view.
By default, BGP is in asynchronous mode.
Step 6: Permit route loop configuration in Hub&Spoke networking (optional)
Generally speaking, PE-CE configuration is completed after you specify the AS
number of neighbor; for the rest configuration, you can keep the system default
values.
In the case of standard BGP, BGP tests routing loop via AS number to avoid
generating routing loop. In the case of Hub&Spoke networking, however, PE
carries the AS number of the local autonomous system when advertising the
routing information to CE, if EBGP is run between PE and CE. Accordingly, the
updated routing information will carry the AS number of the local autonomous
system when route update is received from CE. In this case, PE will not accept the
route update information.
This phenomenon can be avoided by executing the peer allow-as-loop
command, which makes the PE still receives the route update information
containing the local AS number from CE.
Tab le 542 Activate/deactivate peer (group)
Operation Command
Activate the peer (group) peer group-name enable
Deactivate the peer (group) undo peer group-name enable
Tab le 543 Import IGP route
Operation Command
Import IGP route import-route protocol [ process-id ] [ med med ]
Remove IGP route import undo import-route protocol
Tab le 544 Configure BGP asynchronous with IGP
Operation Command
Configure BGP asynchronous with IGP undo synchronization