I wouldn't look at allowing a route in with the same AS as being non-standard. Protocol behavior has to be managed by the administrator based on their own network needs and requirements. One very common tweak that comes to mind is setting next hop self for advertising ebgp learned routes to ibgp neighbors.
In SP networks providing mpls vpn services its common to see the same AS used for all sites in a customer vpn and this requires that the PE routers advertise the routes and that the CE routers accept them etc. Similar to what Patrick said about GRE this could be a management nightmare just for ASN's. -Dan On Jun 10, 2013, at 12:07 PM, Bruce Pinsky <b...@whack.org> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Patrick W. Gilmore wrote: >> On Jun 10, 2013, at 13:36 , Bruce Pinsky <b...@whack.org> wrote: >>> Patrick W. Gilmore wrote: >> >>>>> however, providers a/b at site1 do not send us the two /24s from >>>>> site b.. >>>> >>>> This is probably incorrect. >>>> >>>> The providers are almost certainly sending you the prefixes, but your >>>> router is dropping them due to loop detection. To answer your later >>>> question, this is the definition of 'standard' as it is written into the >>>> RFC. >>>> >>>> Use the allow-as-in style command posted later in this thread to fix your >>>> router. >> >>> Or maintain "standard" behavior by running a GRE tunnel between the two >>> discontinuous sites and run iBGP over the tunnel. >> >> Standard how? I don't remember any such standard, but always willing to be >> educated. >> >> Also, as someone who helps run 2500 non-connected sites, I can't begin to >> imagine the mess of GRE that would require. (OK, not all are in the same >> ASN, but I like hyperbole. :) >> > > "Standard" in the sense of continuing to reject duplicate ASN in the AS > path and not using a BGP knob to allow unnatural behavior. > > If the networks he wishes to advertise for those sites are considered in > the same ASN, there should be continuity between those sites, either > physical or virtual. > > - -- > ========= > bep > > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v2.0.17 (MingW32) > Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ > > iEYEARECAAYFAlG2FdcACgkQE1XcgMgrtybZWQCg8CBl8406YFzmXxZgczPYk3z5 > sL0AoMe26Q+6vkyOEaEHjKb1BM2/W6DO > =AKb8 > -----END PGP SIGNATURE----- >
