peer allow-as-loop (BGP)
Function
The peer allow-as-loop command configures the repeating times of local AS number.
The undo peer allow-as-loop command cancels the function.
By default, it is not allowed to repeat the local AS number.
Format
peer { group-name | ipv4-address | ipv6-address } allow-as-loop [ number ] [ global-as [ vpn-as ] ]
undo peer { group-name | ipv4-address | ipv6-address } allow-as-loop [ number ] [ global-as [ vpn-as ] ]
Parameters
| Parameter | Description | Value |
|---|---|---|
group-name |
Specifies the name of the peer group. |
The name is a string of 1 to 47 characters without any space. It is case-sensitive. |
ipv4-address |
Specifies the IPv4 address of the peer. |
- |
ipv6-address |
Specifies the IPv6 address of the peer. |
- |
number |
Specifies the repeating times of local AS number. |
The value is an integer ranging from 1 to 10. By default, the value is 1. |
global-as |
Indicates a global AS number. |
- |
vpn-as |
Indicates a VPN instance AS number. |
- |
ipv4-address is valid only in the BGP view, BGP-IPv4 unicast address family view, BGP-IPv6 unicast address family view, BGP-VPNv4 address family view, BGP-VPN-Target address family view, and BGP-VPN instance IPv4 address family view.
ipv6-address is valid only in the BGP-IPv6 unicast address family view and BGP-VPN instance IPv6 address family view.
- The global-as and vpn-as parameters apply only to BGP VPN instance IPv4 and BGP VPN instance IPv6 address family views.
Views
BGP view, BGP-IPv4 unicast address family view, BGP-IPv6 unicast address family view, BGP-VPN instance IPv4 address family view, BGP-VPN instance IPv6 address family view, BGP-VPNv4 address family view, BGP-VPN-Target address family view
Usage Guidelines
Usage Scenario
BGP uses AS numbers to detect routing loops. In the Hub and Spoke networking, if EBGP runs between a Hub-PE and a Hub-CE on a Hub site, the route sent from the Hub-PE to the Hub-CE carries the AS number of the Hub-PE. If the Hub-CE sends a routing update to the Hub-PE, the Hub-PE will deny it because the routing update contains the AS number of the Hub-PE.
To ensure proper route transmission in the Hub and Spoke networking, configure all the BGP peers on the path, along which the Hub-CE advertises private network routes to the Spoke-CE, to accept the routes in which the AS number repeats once.
Configuration Impact
If the peer allow-as-loop command is run for a peer or peer group multiple times, the latest configuration overrides the previous one.