3Com 3031 Command Reference Manual page 793

BGP/MPLS VPN Configuration Commands 793
In the case of standard BGP, BGP tests routing loop via AS number. 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 cannot receive the route update information.
This phenomenon can be avoided by using the peer allow-as-loop command,
which makes PE router allow the route update information received from CE to
contain AS number of itself. The allowed maximum number is controlled by using
the parameter asn-imit.
Example
Enable route loop detection in the received route updates.
[3Com-bgp] ipv4-family vpn-instance one
[3Com-bgp-af-vpn-instance] peer 1.1.1.1 allow-as-loop 1
peer as-number Syntax
peer { group-name | [ peer-address group group-name ] } as-number as-number
undo peer { group-name | [ peer-address group group-name] } as-number
as-number
View
BGP view, MBGP vpn-instance view
Parameter
group-name: Peer group name.
peer-address: IP address of a peer.
as-number: Peer end AS number of a peer (group).
Description
Using the peer as-number command, you can configure the remote AS number of
the specified peer (group). Using the undo peer as-number command, you can
remove the remote AS number of the specified peer (group).
By default, a peer of the peer (group) has no AS number.
Example
Set the remote AS number of the specified peer (group) to 100.
[3Com-bgp] peer test as-number 100
peer enable Syntax
peer group-name enable
undo peer group-name enable
View
BGP view, MBGP VPNv4 view