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Uses of BGP Communities

Well we do not use BGP communities here at work but I'm getting to know them for my BSCI exam.

1. Why are there separate well-known communities for no-export and local-AS? They both seem designed to do the same thing.

2. What's the use of non-well-known communities? It seems like they'd accomplish the same thing as route tagging.

Thanks.

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Bronze

Re: Uses of BGP Communities

Hi,

Local-AS will not advertise to other ASes within the confederation while No-Export will.

__

Edison.

8 REPLIES
Hall of Fame Super Bronze

Re: Uses of BGP Communities

1. Not the same thing.

No-Export:

Routes with this community are advertised to only peers in the same autonomous system or to only other subautonomous systems within a confederation. These routes are not advertised to external peers.

Local-AS:

Routes with community are advertised to only peers that are part of the local autonomous system or to only peers within a subautonomous system of a confederation. These routes are not advertised external peers or to other subautonomous systems within a confederation.

2. Yes, it's tagging of routes.

HTH,

__

Edison.

Re: Uses of BGP Communities

"No-Export:

Routes with this community are advertised to only peers in the same autonomous system or to only other subautonomous systems within a confederation. These routes are not advertised to external peers.

Local-AS:

Routes with community are advertised to only peers that are part of the local autonomous system or to only peers within a subautonomous system of a confederation. These routes are not advertised external peers or to other subautonomous systems within a confederation."

The difference then is....?

Hall of Fame Super Bronze

Re: Uses of BGP Communities

Hi,

Local-AS will not advertise to other ASes within the confederation while No-Export will.

__

Edison.

Re: Uses of BGP Communities

You mean other confederations within the AS?

Hall of Fame Super Bronze

Re: Uses of BGP Communities

A confederation is a group of sub-ASes, so the correct term is 'ASes within a confederation'.

__

Edison.

Re: Uses of BGP Communities

Hmmm, and here I thought a confederation WAS a sub-AS.

BGP is not for tiny networks.

Thanks for the xplanation.

Hall of Fame Super Bronze

Re: Uses of BGP Communities

New Member

Re: Uses of BGP Communities

Hello Edison,

Your above Post and Link extremely useful.

~Mirza.

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