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,
refer to the relevant Dell Networking OS Command Line Reference Guide.
The following is a list of the Dell Networking OS version history for this command.
Version Description
9.8(0.0) Introduced on the S3048–ON and S4048–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 — views the information the BGP neighbors exchange.
show ip protocols — views information on routing protocols.
Border Gateway Protocol
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