michiel,
i don't think i could really respond to your query's relating to SONET/SDH. Coming to the usage of control channel management, its only that one could leverage on the faster light weighted hellos of LMP which is order msec, compared to sec's in normal routing protocol, for faster recovery of control channel failures.
Ravi S. Ravindran
Nortel Networks, Ottawa
-----Original Message-----
From: Michiel van Everdingen [mailto:MvanEverdingen@lucent.com]
Sent: Monday, April 15, 2002 10:54 AM
To: Ravindran, Ravi [CAR:0V13:EXCH]
Cc: 'Manoj Sontakke'; Jonathan Lang; ccamp@ops.ietf.org
Subject: Re: Question on LMP.
Hello Ravi, Manoj,
> This is reiterating manoj's question, do we need some kind of association
> between the routing protocol and the LMP which is supposed to provide a
> reliable control channel for the control plane protocols.
1. Do you also set up a control channel between neighbors switching at VC-12 /
VT-1.5 level ? In this case there is no DCC channel between the neighbors.
2. Do you also set up a control channel between neighbors in case there is
a transparent cross connect in between that does not implement LMP/GMPLS ?
I.e. the data link is actually a 'serial compound link'.
Example of my second point, assume e.g. datalink is VC-4:
+------+ +------+ +------+ +------+
| T-|--->--|-C--C-|--->--|-C C-|--->--|-T |
| | A | | B | | C | |
| | | | | | | |
| NE-1 | | NE-2 | | NE-3 | | NE-4 |
+------+ +------+ +------+ +------+
NE-2 does not implement LMP nor GMPLS. It simply is a fixed through-cross-
connect for this data link. In this case, I'm assuming NE-1 and NE-3 need to be
considered as switching neighbors that switch under GMPLS control.
> If we do not have
> this, during a control channel failure (assuming a case where we have
> multiple active control channels and physical interfaces between two
> nodes), the control plane protocols would have to rely on the routing
> protocol to detect the failure and reroute the packets, making the control
> channel management of LMP less efficient.
*If* we need for some reason a control channel between switching neighbors,
why don't we use an LSP to implement this control channel ? Why inventing
again a new mechanism ?
But stepping back a bit, why do we need a 'reliable control channel' at
all ? Why are normal routing protocols not sufficient ?
Thanks,
Michiel
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