Re: Question on LMP.

[Michiel van Everdingen <MvanEverdingen@lucent.com>]

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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| Michiel van Everdingen                                           |
| Systems Engineer                                                 |
| Lucent Technologies - Optical Networking Group                   |
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