Route Server Filters at IXPs and 4-byte ASNs

Jared Mauch jared at
Wed Feb 5 16:04:26 UTC 2014

On Feb 5, 2014, at 9:21 AM, Jeffrey Haas <jhaas at> wrote:

> The wide comms draft (and flex comms, where some of the ideas were pulled in
> from) was intended to address the messier case where the meaning of a
> community was already structured.  To pick on one of the items in the list:
> Coding these using regexes is a PITA, both as an implementor of the
> underlying policy and as a sender who has to remember what the magic value
> means.  Ideally the operator should end up with something simple: 
> Tell AS209, Do not announce to AS foo. Prepend N times to PST peers. Etc.
> Right now, these things are magic values.

When possible (e.g.: here at AS2914) we have used things like this:

65500:nnn	do not announce to peer

where the NNN is the peer ASN.  Using such literal numbering is easier for
the humans involved.  The ability to see what route is learned from specific ASN
is also helpful, as things like AS_PATH are just a bit-string that can be arbitrarily
set and sent by a peer.

I will try to keep my eye open for the draft.

(perhaps see you in Atlanta or London).

- Jared

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