[c-nsp] BGP Regex to allow ISP customers

[Dragan Jovicic]

It's been a while but, the following might do it

^(100_)+([0-9_]+)(_\2)*$

It matches any customer of 100 also accounting for case where both 100 and
customer are prepending.


On Tue, Oct 18, 2016 at 2:28 AM, Randy via cisco-nsp <
cisco-nsp at puck.nether.net> wrote:

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> ---------- Forwarded message ----------
> From: Randy <randy_94108 at yahoo.com>
> To: Nick Cutting <ncutting at edgetg.com>, Brandon Ewing <
> nicotine at warningg.com>, "cisco-nsp (cisco-nsp at puck.nether.net)" <
> cisco-nsp at puck.nether.net>
> Cc:
> Date: Tue, 18 Oct 2016 00:24:23 +0000 (UTC)
> Subject: Re: [c-nsp] BGP Regex to allow ISP customers
>
> ----- Original Message -----
> From: Nick Cutting <ncutting at edgetg.com>
> To: Brandon Ewing <nicotine at warningg.com>; "cisco-nsp (
> cisco-nsp at puck.nether.net)" <cisco-nsp at puck.nether.net>
> Sent: Monday, October 17, 2016 4:32 PM
> Subject: Re: [c-nsp] BGP Regex to allow ISP customers
>
> 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.
>
> From: Brandon Ewing [mailto:nicotine at warningg.com]
> Sent: Monday, October 17, 2016 5:45 PM
> To: cisco-nsp (cisco-nsp at puck.nether.net) <cisco-nsp at puck.nether.net>
> Cc: Nick Cutting <ncutting at edgetg.com>
> Subject: Re: [c-nsp] BGP Regex to allow ISP customers
>
>
> The original message is attached because it is signed.
>
>
> Hi,
> Perhaps something like this:
>
> ip as-path access-list 100 permit ^100_[0-9]*$
> ip as-path access-list 100 permit ^100_([0-9]+)_\1_\1$
>
> first line would match as100 only and as100 and it's customers while the
> second would allow three prepends from customers of as100. I am sure there
> is a better way to do this though...
>
>
> ./Randy
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