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Author Topic: bgp peer address from within the advertised space possible?  (Read 2231 times)

enovation

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bgp peer address from within the advertised space possible?
« on: August 31, 2012, 09:56:21 AM »

Hi,

We are trying to use one router for the IPV6 (BGP) tunnel, and a different one for the BGP advertising. Since a BGP IPV6  tunnel does not come with an extra /64 that is routed over it, we are looking at ways to get this done.

I wonder, would it be possible in BGP to advertise the space from an address within that space?
In normal situations, advertising is done from the tunnel endpoint IPV6 address to its Point to Point counterpart.
HE has the information about the subnet of the space you advertise on record, so it could be possible that this subnet is routed in the tunnel anyway, regardless of it being advertised or not.
If that is the case, then when BGP is for some reason failing, the advertising router would not be locked out because the subnet would not be routed in the tunnel anymore.

Regards,

Maurice

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kcochran

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Re: bgp peer address from within the advertised space possible?
« Reply #1 on: August 31, 2012, 10:33:29 AM »

The prefixes you give at tunnel setup aren't routed to you.  They are collected and exist for filtering purposes.

Both BGP neighbors need to know the address of the other.  If you're not the ::2 address of the link /64, we'll never establish.  If you're more than one v6 hop away, we'll never establish, since the session is set eBGP without multi-hop.
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enovation

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Re: bgp peer address from within the advertised space possible?
« Reply #2 on: September 03, 2012, 01:34:24 AM »

Thank you, that is clear.
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