[124988] in North American Network Operators' Group
Re: Peering Exchange Configurations
daemon@ATHENA.MIT.EDU (Joe Abley)
Thu Apr 8 12:49:36 2010
From: Joe Abley <jabley@hopcount.ca>
In-Reply-To: <20100408164216.GP1403@ronin.4ever.de>
Date: Thu, 8 Apr 2010 12:47:45 -0400
To: Elmar K. Bins <elmi@4ever.de>
X-SA-Exim-Mail-From: jabley@hopcount.ca
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On 2010-04-08, at 12:42, Elmar K. Bins wrote:
> jabley@hopcount.ca (Joe Abley) wrote:
>=20
>>> 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.
>=20
> ...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
