acennami@neupath.com wrote:

That is what he is doing, however if he is advertising the two /19's, from two disconnected sites with the same ASN, they will not be able to reach each other as BGP will interpret this as a path loop.

Yup. I would presume, as they aren't connected, nor running iBGP, they would be running different ASN's. Anything else hurts.

On Wed, Dec 08, 2004 at 12:56:13PM -0500, Richard Irving wrote:

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Rolo Tomassi wrote:

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Hi all,

Please forgive the simplistic nature of the query..

Basically my company is multi-homed with 2 different providers in the UK, and advertising a /18. Now some colleaguges in another part of the world want to break that /18 into two /19's and advertise one /19 and we advertise the other. This is fine, however we are NOT running IBGP in the core, therefore the UK customers in the /19 will not be able to reach the other /19 as there would be a loop detected through EBGP.

Pardon my simplistic solution, try dropping the /18, and -only- advertise the corresponding /19 from each region.

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Now someone mentioned that we could use AS-LOOP-IN feature which will overcome this problem and allow us to route to each other via EBGP. I really think this is a bad idea but until we get an internal link - I dont see a way forward. So... anyone doing this currently in their network or have any "best practices" way round this. I want our company to be good Netizens but still be able to pass traffic between the 2 /19's.

See above. K.I.S.S. (No offense intended ;)

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Any help would be greatly appreciated.

Rolo !

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