peer allow-as-loop (BGP-EVPN address family view)

Function

The peer allow-as-loop command sets the number of local AS number repetitions.

The undo peer allow-as-loop command cancels the configuration.

By default, the local AS number cannot be repeated.

Format

peer ipv4-address allow-as-loop [ number ]

undo peer ipv4-address allow-as-loop

Parameters

Parameter	Description	Value
ipv4-address	Specifies the IPv4 address of a peer.	The value is in dotted decimal notation.
number	Specifies the number of local AS number repetitions.	The value is an integer ranging from 1 to 10. The default value is 1.

Parameter

Description

Value

ipv4-address

Specifies the IPv4 address of a peer.

The value is in dotted decimal notation.

number

Specifies the number of local AS number repetitions.

The value is an integer ranging from 1 to 10. The default value is 1.

Views

BGP-EVPN address family view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
bgp	write

Usage Guidelines

Usage Scenario

BGP uses AS numbers to detect routing loops. The AS numbers in the AS_Path of each received route are matched against the local AS number configured using the bgp command and the fake AS number configured using the peer fake-as command. The largest number of times any of the configured AS numbers is repeated is considered as the maximum number. 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.

Prerequisites

The specified peer has been enabled in the BGP-EVPN address family view.

Configuration Impact

If the peer allow-as-loop command is run for a peer multiple times, the latest configuration overrides the previous one.

Precautions

The peer allow-as-loop command does not take effect on IBGP and BGP in the confederation. This command is used to check whether the routes received from EBGP peers or EBGP peers in the confederation have local ASs. If this command is not configured, the peer allow-as-loop 0 command is used by default. The AS-Loop check is not performed on IBGP and IBGP in the confederation. The minimum number of repetitions is 2, and the value 1 is not displayed.

Example

# Set the number of local AS number repetitions to 2 in the BGP-EVPN address family view.

<HUAWEI> system-view
[~HUAWEI] bgp 100
[*HUAWEI-bgp] peer 10.1.1.9 as-number 200
[*HUAWEI-bgp] l2vpn-family evpn
[*HUAWEI-bgp-af-evpn] peer 10.1.1.9 enable
[*HUAWEI-bgp-af-evpn] peer 10.1.1.9 allow-as-loop 2