Deployment Guide

Command History
Version Description
9.9(0.0) Introduced on the FN IOM.
9.2(0.0) Introduced on the MXL 10/40GbE Switch IO Module.
Usage Information
This command is enabled by default, that is for all updates received from EBGP peers, BGP ensures that the rst
AS of the rst AS segment is always the AS of the peer. If not, the update is dropped and a counter is increments.
To view the “failed enforce-rst-as check” counter, use the show ip bgp neighbors command.
If you disable the enforce-first-as command, it can be viewed using the show ip protocols command.
Related Commands
show ip bgp neighbors — views the information the BGP neighbors exchange.
show ip protocols — views information on routing protocols.
bgp fast-external-failover
Enable the fast external failover feature, which immediately resets the BGP session if a link to a directly connected external peer fails.
Syntax
bgp fast-external-failover
To disable fast external failover, use the no bgp fast-external-failover command.
Defaults Enabled
Command Modes ROUTER BGP
Supported Modes Full–Switch
Command History
Version Description
9.9(0.0) Introduced on the FN IOM.
9.2(0.0) Introduced on the MXL 10/40GbE Switch IO Module.
Usage Information
The bgp fast-external-failover command appears in the show config command output.
bgp four-octet-as-support
Enable 4-byte support for the BGP process.
Syntax
bgp four-octet-as-support
To disable fast external failover, use the no bgp four-octet-as-support command.
Defaults Disabled (supports 2–byte format)
Command Modes ROUTER BGP
Supported Modes Full–Switch
Border Gateway Protocol IPv4 (BGPv4) 297