On 2010-04-08, at 12:42, Elmar K. Bins wrote:
jabley@hopcount.ca (Joe Abley) wrote:
1) Is a private AS typically used for the exchange side of the session? No. Also many exchange points do not run route servers at all, and expect participants to build bilateral BGP sessions directly between each other.
...which is a shame. Routeservers in place gives you a nice benefit upon hooking up to the exchange and before you have even found out who is on the grid (anyone have a list for NOTA?).
I've never had a problem getting a participant list for NOTA from Terremark. One down-side of route servers on a shared exchange fabric is that the layer-2 path through the exchange for the BGP sessions does not always match the layer-2 path through the exchange for traffic. This means that AS1 might continue to learn AS2's routes through the route server even though there's a layer-2 problem that prevents AS1 and AS2's peering routers from talking directly to each other. Hilarity may result. I've never seen such a problem on small exchanges where the layer-2 fabric is simple, but I have seen it more than once on larger, more complicated exchanges. My personal preference is to focus peering energy on bilats, and not to rely on a route server. But I understand the savings in opex that route servers can provide on busy exchanges. Joe