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On Feb 19, 2012 1:15 AM, "Michael Mol" <mikemol@×××××.com> wrote: |
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> |
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> (Sorry for the top-post...I'm mobile atm.) |
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> |
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> My understanding is that core network operators filter ASs for which they |
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don't have a contract for transit. I.e, if I were to get my own PI space, |
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I'd have to pay tier 1 networks (or pay someone to ride on *their* |
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contract) for a contract to have packets destined for my AS to be able to |
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reach me across their network. |
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> |
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Well, yes, but it's the other way around. |
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It's an operator saying "I don't want traffic for $AS_LIST" or "I want |
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traffic only for $AS_LIST". The contents of AS_LIST is set by the operator |
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on the receiving side statically, based on the transit contract. |
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The routers, being the workhorse brutes that they are, don't waste time |
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checking on contracts. |
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So, if a neighbor router suddenly advertise it has a 1-hop distance to |
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*any* AS... the router will immediately begin switching packets toward that |
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neighbor. |
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Rgds, |
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