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New Member

BGP As override

hello friends,

pls explain as-override feature in brief if possible please give me the example

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Silver

Re: BGP As override

Hello Sourabh,

neigh x.x.x.x as-override allows to a PE router to change the private ASN used by a CE node on an eBGP session running on a VRF access link.

the private ASN is changed in the PE ASN.

another CE node on another VRF (=connected to another PE node) will see the eBGP route coming from first site with an AS path of:

provider-ASN provider-ASN

instead of:

provider-ASN site1-ASN

this allows to use the same private ASN on all sites of a customer.

That is a clear management advantage for a service provider.

This because BGP by default doesn't accept BGP routes with an AS path attribute that contains local AS number.

Hope to help

Giuseppe

3 REPLIES
Hall of Fame Super Bronze

Re: BGP As override

Hall of Fame Super Silver

Re: BGP As override

Hello Sourabh,

neigh x.x.x.x as-override allows to a PE router to change the private ASN used by a CE node on an eBGP session running on a VRF access link.

the private ASN is changed in the PE ASN.

another CE node on another VRF (=connected to another PE node) will see the eBGP route coming from first site with an AS path of:

provider-ASN provider-ASN

instead of:

provider-ASN site1-ASN

this allows to use the same private ASN on all sites of a customer.

That is a clear management advantage for a service provider.

This because BGP by default doesn't accept BGP routes with an AS path attribute that contains local AS number.

Hope to help

Giuseppe

New Member

Re: BGP As override

thank you...Giuseppe, for providing nice expln.

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