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Re: Do ATM-based Exchange Points make sense anymore?
- From: David Diaz
- Date: Sun Aug 11 18:28:27 2002
Paul just hit on it. At how many layers do you want protection, and
will they interfere with each other. Granted not all protection
schemes overlap. If there if not a layer 1 failure, and a router
maintains link0 but the card or routers has somehow failed and is no
longer passing packets, I suppose that would have to be caught at
At an (MAN) exchange pt based in S. Fl, the technology is a
multi-node area exchange point (layer 1 technology) based on dwdm and
optical switches. The detection of nodes and failures is done with
enhanced-OSPF. On testing, failure between the farthest two nodes
and recovery took 16ms (approx 95miles dist btw nodes).
Each individual circuit has a choice of protection level. This
allows for no protection for any of a number of reasons. One may be
to not interfere with a protection scheme at a higher level. While
the switches do use OSPF for detection and recovery, they also use
MPLS for reservation of bandwidth. None of this information is
passed onto the customer routers however.
It seems there should be a clear delineation btw the layers and what
protection schemes should run at each. I also believe in separation
of church and state if u will, router companies should play in their
space while optical companies show stay in theirs. While it makes
sense for some information to pass btw differing types of equipment
(such as ODSI protocol or UNI 1.0) integration of the protection
schemes runs a high degree of a cascade failure, or susceptibility to
an exploit attach.
As an added thought, the same MAN exchange point can do intranode
connections (hairpinning). So that the same node that is used in
internodal transport and peering, can also be used within a colo as
an intelligent cross-connect box. This would allow for visibility
and monitoring within the colo and even customer network management
of their cross connects.
I suppose the discussion is what do you want from your exchange pt
operator and what do you NOT want. Many people would not feel
comfortable that circuit operators have visibility and maintain stats
on even NUMBER of packets passed....
At 9:21 +0000 8/10/02, Paul Vixie wrote:
warning: i've had one "high gravity steel reserve" over my quota. hit D now.
The issue I'm trying to address is to figure out how to extend the
that can be achieved with tuned IGP's with subsecond convergence across
an exchange point without suffering a one to five minute delay blackholing
why on god's earth would subsecond anything matter in a nonmilitary situation?
are you willing to pay a cell tax AND a protocol complexity tax AND a device
complexity tax to make this happen? do you know what that will do do your
TCO and therefore your ROI? you want to pay this tax 100% of the time even
though your error states will account for less than 0.001% of the time? you
want to have the complexity as your most likely source of (false positive)
As far as I understand, this "complexity" just got added with Neighbor
Discovery on IPv6.
if so, then, you misunderstand.
Smotons (Smart Photons) trump dumb photons