bgp_path multiple AS match on single rule

[Ondrej Zajicek]

On Mon, Jul 08, 2013 at 09:35:02AM +0300, Javor Kliachev wrote:
> Hello,
>
> I'm wondering, is there any way to configure following example to single  
> rule only.
>
> if bgp_path ~ [= * 100 * =] then return false;
> if bgp_path ~ [= * 200 * =] then return false;
> if bgp_path ~ [= * 300 * =] then return false;
> if bgp_path ~ [= * 400 * =] then return false;
>
> On this way, If we want to filter many ASs, it seems that we should  
> generate too much rows.

Well, you could replace that with this:

    if 10 ~ bgp_path then return false;

which is probably slightly faster, but you still need all the rows.
If you would test just for last (or first) ASN, you could use:

    if bgp_path.last ~ [10, 20, 30, 40, ... ] then return false;

Perhaps we should implement this:

    if bgp_path ~ [10, 20, 30, 40, ... ] then return false;

(i.e. check every ASN from bgp_path against set of numbers) That would
be simple to implement, consistent with our filtering features for
community lists and works fast for a large sets of ASN.

We don't support full regular expressions for bgp_path matching, just the
shell-like wildcard patterns.

-- 
Elen sila lumenn' omentielvo

Ondrej 'SanTiago' Zajicek (email: santiago at crfreenet.org)
OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
"To err is human -- to blame it on a computer is even more so."
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