[124982] in North American Network Operators' Group
Re: Peering Exchange Configurations
daemon@ATHENA.MIT.EDU (Joe Abley)
Thu Apr 8 12:30:28 2010
From: Joe Abley <jabley@hopcount.ca>
In-Reply-To: <9A0CBD30-7766-4773-9B40-20A28F4415EA@gmail.com>
Date: Thu, 8 Apr 2010 12:29:57 -0400
To: Brad Fleming <bdflemin@gmail.com>
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 12:02, Brad Fleming 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.
> 2) Are RFC1918 IPs typically used for the p2p links into the exchange?
No. Participants in an exchange typically number their exchange-facing =
interfaces out of a larger (non-p2p) subnet, e.g. an IPv4 /24 or /23, or =
an IPv6 /48 (or both).
> 3) Do peering exchanges typically remove their AS from the path =
advertised to exchange participants?
Some do, I hear. See above regarding route servers.
> 3a) If no: Do participants typically preference exchange-learned =
routes over other sources?
Many people apply a higher LOCAL_PREF to routes learnt over an exchange =
in order to prefer cheap peering routes over more expensive transit =
routes. This is not universal, however. I know of networks who =
deliberately flatten LOCAL_PREF across peering and transit sessions in =
order to use different discriminators for exit selection (e.g. AS_PATH =
length).
> 4) Do exchanges typically support the following address families?
> IPv4 Multicast
> IPv6 Unicast
> IPv6 Multicast
I'm quite ignorant of multicast. IPv6 unicast peering is common.
> In exchanges where a route server is employed:
> 4) Do participants have a p2p link into a simple routing environment =
then multi-hop to a route server?
In all exchange points I have seen where a route server was available, =
the route server appears on the shared fabric numbered just as any other =
participant would be.
> 5) I see that Bird, OpenBDGd, and Quagga are all options for route =
server software. Does one of those packages stand out as the clear =
current choice for production peering exchanges?
BIRD seems to be the choice du jour based on idle hallway chatter, but I =
have not compared them.
Joe
