Cisco Cisco IOS Software Release 12.0(3)S

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BGP Enforce the First Autonomous System Path

The BGP Enforce the First Autonomous System Path feature is used to configure a Border Gateway
Protocol (BGP) routing process to discard updates received from an external BGP (eBGP) peers that do
not list their autonomous system (AS) number as the first AS path segment in the AS_PATH attribute of
the incoming route.

Feature History for BGP Enforce the First Autonomous System Path feature

Finding Support Information for Platforms and Cisco IOS Software Images

Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image
support. Access Cisco Feature Navigator at

http://www.cisco.com/go/fn

. You must have an account on

Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at
the login dialog box and follow the instructions that appear.

Contents

•

How to Enable First AS Path Verification, page 2

•

Configuration Example for First AS Path Verification, page 2

•

Additional References, page 3

•

Command Reference, page 4

Release

Modification

12.0(3)S This

feature was introduced.

12.0(26)S

The default behavior for this feature was changed to enabled in Cisco IOS
Release 12.0(26)S.

12.2(18)S

This feature was integrated into Cisco IOS Release 12.2(18)S.

12.3(2)

This feature was integrated into Cisco IOS Release 12.3(2).

12.3(2)T

This feature was integrated into Cisco IOS Release 12.3(2)T.