RE: Dropping the Local Overbooking Multiplier (LOM) method from DS-TE specs?

["Ash, Gerald R (Jerry), ALABS" <gash@att.com>]

All,

I'm not sure where we stand on keeping LOM or dropping LOM.

If we keep LOM, it is possible to re-define LOM so as to simplify the rather complicated 3-way approach to overbooking that now exists:

LSPOMc = LSP overbooking multiplier for CTc
LSOM = link size overbooking multiplier
LOMc = local overbooking multiplier for CTc

If LOM is retained, Wai Sum and I propose to redefine LOM (calling it LOM') to provide an overall simplification of this 3-way overbooking complexity, as follows.

Define:

LSPOMc = LSP overbooking multiplier for CTc
LSOM = link size overbooking multiplier
LSOM = maximum reservable bandwidth/maximum link bandwidth
LOMc = local overbooking multiplier for CTc (original definition of LOMc)
LOM'c = redefined local overbooking multiplier LOMc for CTc
LOM'c = LSOM * LSPOMc * LOMc

Given:
requested LSP CTc = RSVP-TE Tspec LSP bandwidth specified in TLV

Then the following general equation applies:
reserved CTc = requested LSP CTc/LOM'c                       (1)

wherein there are several cases of equation (1) for reserved CTc:

1. Link Size Overbooking only:
    LSPOMc = 1, LOMc = 1, for all c
    LOM'c = LSOM, or equivalently
    reserved CTc = requested LSP CTc/LSOM = requested LSP CTc/LOM'c
2. LSP Size Overbooking only:
    LSOM = 1, LOMc = 1, for all c
    LOM'c = LSPOMc for all c, or equivalently
    reserved CTc = requested LSP CTc/LSPOMc = requested LSP CTc/LOM'c
3. Both Link Size Overbooking and LSP Size Overbooking:
    LOMc = 1, for all c
    LOM'c = LSOM * LSPOMc, or equivalently
    reserved CTc = requested LSP CTc/(LSOM * LSPOMc) = requested LSP CTc/LOM'c
 4. LOM in conjunction with the above cases 1, 2, or 3
    reserved CTc = requested LSP CTc/LOM'c

In this model, the aggregate constraint becomes:

 o SUM (Reserved(CTc)) <= MLBW                               (2)
     for all "c" in the range 0 <= c <= (MaxCT-1)

We believe that this simplification, as summarized in equations (1) and (2) above, is worthwhile if LOM is retained.

Comments welcome.

Thanks,
Jerry & Wai Sum