peer public-as-only (BGP)

Function

The peer public-as-only command configures a device to delete private AS numbers (if any) from the AS_Path attribute before sending update packets.

The undo peer public-as-only command configures BGP to send BGP update packets with private AS numbers.

By default, private AS numbers can be contained in the BGP update packets to be advertised.

Format

peer { group-name | ipv4-address | ipv6-address } public-as-only [ force ]

undo peer { group-name | ipv4-address | ipv6-address } public-as-only

Parameters

Parameter	Description	Value
group-name	Specifies the name of a 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.
ipv4-address	Specifies the IPv4 address of a peer.	The value is in dotted decimal notation.
ipv6-address	Specifies the IPv6 address of a peer.	The address is a 32-digit hexadecimal number in the X:X:X:X:X:X:X:X format.
force	In the following two cases, BGP does not delete the private AS number after the command is used: The AS_Path of a route contains the AS number of the peer. In this case, deleting the private AS numbers may lead to a routing loop. The AS_Path list contains both public network AS numbers and private AS numbers, indicating that the route has passed through the public network. Deleting the private AS numbers may lead to a forwarding error. To enable the device to delete the private AS numbers from the AS_Path attribute before sending update packets even in the preceding scenarios, specify force in the command.	-

ipv4-address is valid only in the BGP view, BGP-IPv4 unicast address family view, BGP-VPN-Target family view, BGP-IPv6 unicast address family view, BGP-VPNv4 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.

Views

BGP view, BGP-IPv4 unicast address family view, BGP-VPN instance IPv4 address family view, BGP-VPN instance IPv6 address family view, BGP-VPNv4 address family view, BGP-IPv6 unicast address family view, BGP-VPN-Target family view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

In general, the number of an AS ranges from 1 to 4294967295. The public AS number ranges from 1 to 64511, and 65536 (1.0 in the format of x.y) to 4294967295 (65535.65535 in the format of x.y), and the private AS number ranges from 64512 to 65534. 65535 is used as the reserved AS number in certain circumstances.

Public AS numbers can be used on the Internet. Private AS numbers cannot be advertised to the Internet, and they are used only within ASs. If private AS numbers are advertised to the Internet, a routing loop may occur. After this command is configured, if the AS path attribute contains only private AS numbers, BGP deletes the private AS numbers and then advertises these update routes.

Prerequisites

A peer or peer group has been configured using the peer as-number command.

Configuration Impact

If the peer public-as-only command is run for a peer group, the peers of the peer group inherit the configuration.

Precautions

The command is applicable only to EBGP peers.

Example

# Configure BGP to send update packets without private AS numbers to the peer.

<sysname> system-view

[sysname] bgp 100

[sysname-bgp] peer 1.1.1.2 as-number 200

[sysname-bgp] ipv4-family unicast

[sysname-bgp-af-ipv4] peer 1.1.1.2 public-as-only

# Configure BGP to send update packets without private AS numbers to a peer group named test.

<sysname> system-view

[sysname] bgp 100

[sysname-bgp] group test external

[sysname-bgp] ipv6-family

[sysname-bgp-af-ipv6] peer test enable

[sysname-bgp-af-ipv6] peer test public-as-only