On Fri, 21 Nov 2014 11:07:49 +0200, Mark Tinka <mark.tinka@seacom.mu> said: >> We own an AS number and our IP space but at the last minute >> learned our state network is advertising our network using two >> different ASNs (neither ours) This will work, as in the BGP path selection algorithm will work as designed in this situation. But it also means that the routing policy is out of your control which is kind of the point of having an ASN! It also makes it harder to track down who is operationally responsible for that address space since it appears to the outside world to be in two (or three! different places). I'd say don't do this unless you really have no choice. > Why aren't you originating your own prefixes and ASN by > yourselves, since you own both? Good question. We (AS60241) almost ended up doing similarly for a while. Because of a close association with the universities in Scotland, we discussed the possibility of transit via JANET. This turned out to be difficult because they run a whole bunch of private ASNs internally -- unlike in North America where universities typically have their own real one. So it would have been us -> private stuff -> AS786 and for some reason that I forget they were unable to remove private ASNs from the path. The best that might have been possible would be to have had them announce our networks with synchronisation on, which would have meant the outside world would have seen them originating in both AS786 and AS60241. Icky. We (mutually) decided against this. Just to say that there are strange, but not completely unreasonable circumstances in which this can happen... -w