3com 8807 Guia De Referência

Use the peer allow-as-loop command to allow loop in the route updates in the 
Hub & Spoke networking mode.

Use the undo peer allow-as-loop command to prohibit loop in the route 
updates.

By default, loop is prohibited in the received routing updates; by using the peer 
allow-as-loop command, loop is allowed in the received routing updates. The 
default value of asn-limit argument is 3.

Standard BGP tests loop using AS number. However, on a Hub & Spoke network 
running EBGP between PE and CE, PE carries its own AS number when advertising 
route information to CE. Accordingly, the updated route information will contain 
PE’s AS number when it is sent from CE. In this case, PE will not accept the route 
updates.

You can avoid this by using the peer allow-as-loop command, which makes PE 
router allow the route updates from CE to contain its AS number. You can define 
asn-imit to control the maximum times for which AS number is received by PE.

# Enable route loop.

[3Com-bgp] ipv4-family vpnv4

 

[3Com-bgp-af-vpn] peer 1.1.1.1 allow-as-loop 1 

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

VPN-instance sub-address family view

group-name: Name of a peer group, consisting of 1 to 47 alphanumeric 
characters.

peer-address: IP address of peer group.

as-number: Opposite AS number of a peer (group).

Use the peer as-number command to configure the opposite AS number of a 
specified peer (group).

Use the undo peer as-number command to remove the opposite AS number of 
a specified peer (group).

By default, the opposite end of a peer (group) has no AS number.