North American Network Operators Group

Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical

Re: Question on the topology of Internet Exchange Points

  • From: bmanning
  • Date: Thu Feb 14 12:36:22 2008

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 <>, 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.