Very good catch Igor. See in line.
Igor Bryskin wrote:
--snip--
2. Considering wavelength conversion inevitably brings to the problem
of looped paths, which is a completely new ball game in path
computation, and I am surprised that the issue was never mentioned in
the draft.
--> How is this different from the "looping" that can occur with a TDM
multiplexer in a drop and continue mode? Also in these two circuit
cases (TDM, and optical) do we have the same danger as in the packet
case where looping traffic can greatly degrade other flows. Was there
some general looping concerns already published for GMPLS with respect
to circuits?
IB>> There is a profound difference. I am not talking here about
accidental looping, rather about deliberate looping: if some nodes can
perform wavelength conversion while others can not, then you will want
to route the connection to one or several conversion points and after
that get it back on the main path. In other words you will
deliberately request, say, a PCE to produce looped path, and then
GMPLS RSVP-TE to signal looped path, which is completely out of normal
paradigm of work for both PCE and RSVP.
--> I thought you were worried about accidental loops. I didn't even
consider what you are talking about "looping", but would RSVP processing
get fouled up? It sure looks like a loop at the "node" level.
In the ERO the "node" subobject (IP4, IP6, AS) could definitely be
repeated, but with a different "Label ERO" subobject appended. This is
definitely something somebody would not to in the MPLS or TDM case.
I'll be sure to add it as an important difference in the next revision.
Thanks!
Cheers,
Igor
------------------------------------------------------------------------
--snip--
--
===================================================
Dr Greg Bernstein, Grotto Networking (510) 573-2237
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