Service Manual

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 Networking OS Command Line Reference Guide.
Version Description
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.
Related
Commands
• show ip bgp neighbors — view the information the BGP neighbors exchange.
• show ip protocols — view information on routing protocols.
Border Gateway Protocol 452