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Re: Multi-homed BCP38

2014-01-09 12:57:54
On Thu, Jan 9, 2014 at 1:45 PM, John Levine <johnl(_at_)taugh(_dot_)com> wrote:
It looks like the sites John talked to are multihomed, NOT doing
routing at their edge (??), and yet wanting to filter? I don't think

that's not clear, from john's description at least.

I can ask (the meeting's not over yet) but I gather that these are
multihomed customers who don't do BGP.  The ISP knows what ranges it's
routing to the customer, but it doesn't know what ranges are routed to
the same customer by someone else.

if they don't do bgp .. .then you'd expect only static routing and
thus you know exactly what they ought to be sourcing.

There are pathological (aka: stupid) cases of multihomed to 2 isps,
getting static-routing of each isp's PA space on only that one ISP...
and default routing up both pipes... but really that's just broken and
dumb, so getting customers to fix this by filtering is a fine answer.

-chris

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