For a given interconnection between the upstream ISPs for the two site, once the direct link goes down, the time required for site A to learn the new route to site B and vice versa would be different with the different proposed solutions, right? Thanks and best regards
On Sat, Jun 6, 2009 at 12:40 PM, Ivan Pepelnjak <i...@ioshints.info> wrote: > > To rephrase the OP's question, would it be BCP to acquire a > > second ASN, and without further de-aggregating, continue > > advertising each site's IP space to the DFZ, but from > > dissimilar ASs as opposed to the same one? > > This would definitely be the best approach. You're not introducing new IP > prefixes and you're not extending AS paths, so the net effect on the global > BGP routing is zero (OK, you might have to use the 4 byte AS number :). > > Just make sure that both ISPs you connect to allow you to advertise > "transit" prefixes. If site A public link goes down, but the private link > is > up, site B will advertise its own address space plus site A's address space > with an extra AS number in the AS path (and the upstream ISP might filter > that). > > Ivan > > http://www.ioshints.info/about > http://blog.ioshints.info/ > > > -- Muhammad Saqib Ilyas PhD Student, Computer Science and Engineering Lahore University of Management Sciences