ibgp and regexp

[Ramin Malekghasemi]

Hi i have to router A and B 

Router A and B have same Asnumber 

Router A is uplink Router B 

In router A how used  regexp ??

used show ip bgp regexp . 

only show me ebgp prefixs doonot show my ibgp prefixs origin is router B

[MHM Cisco World]

This link not cover all cases

Thanks 

MHM

[MHM Cisco World]

Can I see show ip bgp

MHM

[M02@rt37]

Hello @Ramin Malekghasemi 

Try this command:

show ip bgp regexp _[0-9]+$

This command will show prefixes where the last AS is an external one (eBGP-learned prefixes).

[Ramin Malekghasemi]

test this only show me ebgp prefix

[paul driver]

Hello
You could also try the below, this should show all prefixes with a populated as-path seq

sh ip bgp regexp .+

[Ramin Malekghasemi]

Test this too show only ebgp prefixes

[Harold Ritter]

Hi @Ramin Malekghasemi ,

If you only want to see prefixes originated in the local AS, you need to use the following command:

sh ip bgp regexp ^$

Regards,

[paul driver]

Hell
that what you wanted wasn’t it-these if you want local routes then as stated by @Harold Ritter   reg expression  ^$ will show local routes 

[MHM Cisco World]

Use 

_ x $ 

Where x is the AS of ibgp

MHM

[Harold Ritter]

Hi @MHM Cisco World ,

Bear in mind that the AS number is not inserted when the update is being sent to an iBGP neighbour, but rather when it is being sent to an eBGP neighbor. The command you are suggesting will therefore not show the prefixes originated by the local AS, unlike ^$ would.

Regards,

[MHM Cisco World · Accepted solution]

Locally originate Vs originate in AS 

        ^$              Vs         _ x $

I think this different' I will try both in lab 

If I have time 

Thanks 

MHM

[Harold Ritter]

Hi @MHM Cisco World ,

Whether a prefix is locally originated or by another router in the same AS, the local AS number will not show. The local AS number is only added to the AS path when the update is sent to a neighbor in a remote AS.

Regards,

[MHM Cisco World]