Reference Guide

IPv6 Border Gateway Protocol (IPv6 BGP) | 743
Command Modes
ROUTER BGP
Usage
Information
This 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
incremented. Use the show ip bgp ipv6 unicast neighbors command to view the “failed enforce-first-as
check counter.
If enforce-first-as is disabled, it can be viewed via the show ip protocols command.
Related
Commands
Command
History
bgp fast-external-fallover
c e
Enable the fast external fallover feature, which immediately resets the BGP session if a link to a
directly connected external peer fails.
Syntax
bgp fast-external-fallover
To disable fast external fallover, enter no bgp fast-external-fallover.
Defaults
Enabled
Command Modes
ROUTER BGP
Command
History
Usage
Information
The bgp fast-external-fallover command appears in the show config command output.
bgp four-octet-as-support
c e
Enable 4-byte support for the BGP process
Syntax
bgp four-octet-as-support
To disable fast external fallover, enter no bgp four-octet-as-support.
Defaults
Disabled (supports 2-Byte format)
Command Modes
ROUTER BGP
show ip bgp ipv6 unicast
neighbors
Display IPv6 routing information exchanged by BGP neighbors.
show ip protocols View Information on routing protocols.
Version 8.4.2.1 Introduced on C-Series and S4810.
Version 8.2.1.0 Introduced on E-Series ExaScale
Version 7.4.1.0 Introduced on E-Series TeraScale
Version 8.4.2.1 Introduced on C-Series and S4810.
Version 8.2.1.0 Introduced on E-Series ExaScale
Version 7.4.1.0 Introduced on E-Series TeraScale