Re: LCAS and draft-mannie-ccamp-gmpls-lbm-tdm-00.txt

[Huub van Helvoort <hhelvoort@lucent.com>]

Eric,

Ia also had a look at your

> Simple example:
> 
> 1) you first signal an additional VC/SPE to the destination (via a Path).

[hvh] I don't see any difference with LCAS.

> 2) the destination knows exactly which VC/SPE is added (via the label).

[hvh] isn't this already done in step 1) ?

> 3) the new VC is unequipped (indicated in POH C2 (for HOVC)),
>    so the VC/SPE is not yet added to concatenated signal.

[hvh] G.806 clause 6.2.1.1: unequiped is an indication for loss of
      connectivity. This can also be monitored at intermediate points.
      If it should be interpreted as indicated, G.806 has to be changed
      as well as the installed base.

> 4) then, you wait at the source for a confirmation from the destination
> (i.e. Resv).

[hvh] here signals in the transport plane (C2) and control plane (Resv)
      are mixed, imho this is worse than having it fully in the control
      or ttransport plane.

> 5) the source "equip" the VC/SPE and sends.

[hvh] I am missing the exact definition of when the first bit is sent.

> 6) the destination sees in the POH that the VC is "equipped" (transition).

[hvh] where is the definition of the validation for this detection?

> The difference between LCAS and LBM is that LCAS uses an additional explicit
> indication in the overhead to say "this is the payload" to use. LBM doesn't
> change the SDH/SONET overhead, while LCAS changes the SDH/SONET overhead :-)

[hvh] the explicit indication is required in order not to loose data
      (similar to pointer justification process).

> LCAS uses a new field in the POH (CTRL) to know when the new VC transitions
> to a significant payload. LBM proposes to do the same simply by looking at
> the C2 (for HOVC) transition - regular SDH/SONET field that will change
> anyway and that is used to indicate the type of payload.

[hvh] in regular SDH/SONET C2 is fixed

> To be more precise about LCAS (I copy from the LCAS specification, section
> 6.3.1): "The first container frame to contain payload data for the new
> member shall be the container frame immediately following the container
> frame that contained the last bit(s) (i.e. the CRC) of the control packet
> with NORM/EOS message for that member" (the LCAS control packet).
> 
> So, LCAS waits for the last bit of the appropriate LCAS control packet in
> the POH with the appropriate transition of its CTRL field. LBM waits simply
> for the appropriate C2 (for HOVC) or V5 (for LOVC) transition in the POH
> (don't change SDH/SONET).

[hvh] 6.3.1 describes the insertion after validation, LBM needs also to
      describe the validation process for C2 and the exact insertion.

> By the way, this is version 0 of the draft and it was just posted.
> 
> Suggestions, technical comments and improvements are welcome.
> 
> I would appreciate if people could first read and speak before shooting
> directly :-)

Here in the Netherlands it is illegal to carry guns, so I cannot shoot.
And shooting make more mess that it resolves anyway.

Cheers, Huub.
-- 
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