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

Format

peer group-name allow-as-loop [ number ]

undo peer group-name allow-as-loop

Parameters

Parameter	Description	Value
group-name	Specifies the name of a BGP EVPN peer group.	The name is a string of 1 to 47 case-sensitive characters, with spaces not supported. When double quotation marks are used around the string, spaces are allowed in the string.
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

group-name

Specifies the name of a BGP EVPN peer group.

The name is a string of 1 to 47 case-sensitive characters, with spaces not supported. When double quotation marks are used around the string, spaces are allowed in the string.

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 group has been enabled in the BGP-EVPN address family view.

Configuration Impact

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

Precautions

The peer allow-as-loop command does not apply to IBGP peers or sub-confederation BGP peers. The command only checks whether routes received from EBGP peers and sub-confederation EBGP peers carry the local AS number. If the command is not run, the implementation is equivalent to the peer allow-as-loop 0 configuration. The minimum value is 2 and the value 1 has no configuration display.

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] group gp external
[*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 gp enable
[*HUAWEI-bgp-af-evpn] peer 10.1.1.9 group gp
[*HUAWEI-bgp-af-evpn] peer gp allow-as-loop 2