[c-nsp] BGP Regex to allow ISP customers

[Jon Lewis]

On Mon, 17 Oct 2016, Nick Cutting wrote:

> Thank you for your answer.
>
> The problem is I do not know the ASN's of the ISP's customers.
> Robert - I am afraid that this particular ISP does not have a community for this, nor can they send me just their customer routes.

Since you don't know the ISP's customer ASN's, if they're a small enough 
ISP (few to no peers, and just a couple of transits), you could do an 
as-path ACL like
deny _100_transitA_
deny _100_transitB_
deny _100_peer1_
etc., ending with
permit _100_

It's not really clear what you're trying to accomplish though.  If you 
just want customer routes from them, why not ask them to only send 
customer routes?  The obvious answer to which, I suppose, is that if they 
don't have communities that would indicate which routes are customer 
routes, they're probably incapable of making that route advertisement 
decision on their end.

----------------------------------------------------------------------
  Jon Lewis, MCP :)           |  I route
                              |  therefore you are
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