Administrator Guide

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bgp enforce-first-as

Disable (or enable) enforce-first-as check for updates received from EBGP peers.

Syntax

bgp enforce-first-as

To turn off the default, use the no bgp enforce-first-as command.

Defaults Enabled

Command Modes ROUTER BGP

Command History

This guide is platform-specific. For command information about other platforms, see the relevant Dell EMC

Networking OS Command Line Reference Guide.

Version Description

9.10(0.1) Introduced on the S6010-ON and S4048T-ON.

9.10(0.0) Introduced on the S3148.

9.8(2.0) Introduced on the S3100 series.

9.8(0.0P5) Introduced on the S4048-ON.

9.8(0.0P2) Introduced on the S3048-ON.

9.7(0.0) Introduced on the S6000–ON.

9.0.2.0 Introduced on the S6000.

8.3.19.0 Introduced on the S4820T.

8.3.11.1 Introduced on the Z9000.

8.3.7.0 Introduced on the S4810.

7.8.1.0 Introduced on the S-Series.

7.7.1.0 Introduced on the C-Series.

7.4.1.0 Introduced.

Usage Information

This command is enabled by default, that is for all updates received from EBGP peers, BGP ensures that the first

AS of the first AS segment is always the AS of the peer. If not, the update is dropped and a counter is increments.

Use the show ip bgp neighbors command to view the “failed enforce-first-as check” counter.

If you disable the enforce-first-as command, it can be viewed using the show ip protocols command.

In the event of an enfore-first-as check failure, the existing BGP session is flapped.

Commands

• show ip bgp neighbors — view the information the BGP neighbors exchange.

• show ip protocols — view information on routing protocols.

bgp fast-external-fallover

Enable the fast external fallover feature, which immediately resets the BGP session if a link to a directly connected external peer fails.