On 11/6/07, Tony Sarendal <[EMAIL PROTECTED]> wrote:
>
> New version. Less duplication and a nice feature as bonus.
> With softreconfig in enabled the looped prefixes are accepted
> into the Adj-RIB-In.
>
> This means that I can tell if my neighbor AS is using
> a path via myself. Either I'm tired or that is cool.
>
> router-02# bgpctl show rib 192.168.0.0
> flags: * = Valid, > = Selected, I = via IBGP, A = Announced
> origin: i = IGP, e = EGP, ? = Incomplete
>
> flags destination gateway lpref med aspath origin
> *> 192.168.0.0/16 192.168.100.5 100 0 65100 i
> * 192.168.0.0/16 172.17.1.1 100 0 65200 65100 i
> * 192.168.0.0/16 172.17.1.5 100 0 65200 65200 65200
> 65200 65100 i
> router-02#
>
> I now kill the peering that 65200 has to 65100, removing their
> direct path to 192.168.0.0/16.
>
> router-02# bgpctl show rib 192.168.0.0
> flags: * = Valid, > = Selected, I = via IBGP, A = Announced
> origin: i = IGP, e = EGP, ? = Incomplete
>
> flags destination gateway lpref med aspath origin
> *> 192.168.0.0/16 192.168.100.5 100 0 65100 i
> router-02#
>
> Sweet, the looping issue is gone.
> Here is the bonus:
>
> router-02# bgpctl show rib neigh 172.17.1.5 in | grep 65300
> * 172.17.0.2/32 172.17.1.5 100 0 65200 65300 i
> * 192.168.0.0/16 172.17.1.5 100 0 65200 65300 65100 i
> * 192.168.100.4/30 172.17.1.5 100 0 65200 65300 i
> router-02#
>
> I now see the paths that the peer uses my network to access.
> Note that this depends a bit on remote implementation.
> I think this works agains a cisco router.
>
> /Tony
>
>
> Index: rde.c
> ===================================================================
> RCS file: /cvs/src/usr.sbin/bgpd/rde.c,v
> retrieving revision 1.228
> diff -u -r1.228 rde.c
> --- rde.c 16 Sep 2007 15:20:50 -0000 1.228
> +++ rde.c 6 Nov 2007 17:08:50 -0000
> @@ -919,12 +919,6 @@
> /* shift to NLRI information */
> p += 2 + attrpath_len;
>
> - /* aspath needs to be loop free nota bene this is not a hard error
> */
> - if (peer->conf.ebgp && !aspath_loopfree(asp->aspath, conf->as)) {
> - error = 0;
> - goto done;
> - }
> -
> /* parse nlri prefix */
> while (nlri_len > 0) {
> if ((pos = rde_update_get_prefix(p, nlri_len, &prefix,
> @@ -977,10 +971,18 @@
> if (fasp == NULL)
> fasp = asp;
>
> - rde_update_log("update", peer,
> &fasp->nexthop->exit_nexthop,
> - &prefix, prefixlen);
> - path_update(peer, fasp, &prefix, prefixlen, F_LOCAL);
> -
> + rde_update_log("update", peer,
> + &fasp->nexthop->exit_nexthop,&prefix,
> + prefixlen);
> + /* handle an update with loop as a withdraw */
> + if (peer->conf.ebgp && !aspath_loopfree(asp->aspath,
> + conf->as))
> + prefix_remove(peer, &prefix, prefixlen,
> + F_LOCAL);
> + else
> + path_update(peer, fasp, &prefix, prefixlen,
> + F_LOCAL);
> +
> /* free modified aspath */
> if (fasp != asp)
> path_put(fasp);
> @@ -1075,9 +1077,15 @@
>
> rde_update_log("update", peer,
> &asp->nexthop->exit_nexthop,
> - &prefix, prefixlen);
> - path_update(peer, fasp, &prefix,
> prefixlen,
> - F_LOCAL);
> + &prefix, prefixlen);
> + /* handle an update with loop as a
> withdraw */
> + if (peer->conf.ebgp &&
> +
> !aspath_loopfree(asp->aspath,conf->as))
> + prefix_remove(peer, &prefix,
> + prefixlen,F_LOCAL);
> + else
> + path_update(peer, fasp, &prefix,
> + prefixlen,F_LOCAL);
>
> /* free modified aspath */
> if (fasp != asp)
> --
> ---
> Tony Sarendal - [EMAIL PROTECTED]
> IP/Unix
> -= The scorpion replied,
> "I couldn't help it, it's my nature" =-
>
>
Added is if course the drawback that a softreconfig inbound brings
back the behaviour I was trying to avoid...
Need to stick code into rde_softreconfig_in() if I want this, not nice.
