[102438] in North American Network Operators' Group
Re: Question on the topology of Internet Exchange Points
daemon@ATHENA.MIT.EDU (bmanning@vacation.karoshi.com)
Thu Feb 14 12:28:43 2008
Date: Thu, 14 Feb 2008 17:26:09 +0000
From: bmanning@vacation.karoshi.com
To: Kai Chen <kch670@eecs.northwestern.edu>
Cc: nanog@merit.edu
In-Reply-To: <e81393830802140902n1dbff023xac93178b51306eeb@mail.gmail.com>
Errors-To: owner-nanog@merit.edu
On Thu, Feb 14, 2008 at 11:02:54AM -0600, Kai Chen wrote:
> A typical Internet Exchange Point (IXP) consists of one or more network
> switches <http://en.wikipedia.org/wiki/Network_switch>, to which each of the
> participating ISPs connect. We call it the exchange-based topology. My
> question is if some current IXPs use directly-connected topology, in
> which ISPs just connect to each other by direct link, not through a network
> switch?? If so, what's the percentage of this directly-connected case?
>
> Kai
the "directly-connected" case - over point2point link is not
per se, an Internet Exchange Point (IXP) in that there is no
chance of multiplexing the link to connect more than one
provider over that direct link.
the direct link can be a dedicated fiber pair, a cat5 cable,
conditioned copper pair or coax or combination of these layer
one transmission media (yeah, sat, microwave, avian carrier etc...)
depending on proximity and cost.
latency is usually less of an issue here, as is buffering, since there
is a single endpoint. Its also much easier to maintain security
associations on direct links.
--bill
