RE: Reflecting new-MAM/SAM definition in diff-te drafts

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

Francois, All,

> 1)when per-CT LOMs are not used:
> "o	for each value of b in the range 0 <= b <= (MaxCT - 1):
>             		Reserved (CTb) <= BCb,"
> 
> 1)when per-CT LOMs are  used:
> "-	for each value of b in the range 0 <= b <= (MaxCT - 1):
>             		Normalised(CTb) <= BCb,"
> 
> So I think we all agree with that part of the formula, right?

Yes, I think we agree on this.

> Again, here I agree that the formula needs to be applied to Normalised
> bandwidth when per-CT LOMs are used.

Right.  So we need to specify what that formula is.  We have suggested this formula:

    SUM (Reserved(CTc)/LOM(CTc)) <= Max Link Bandwidth
     for all "c" in the range 0 <= c <= (MaxCT-1)

or, equivalently:

   SUM (Normalized(CTc)) <= Max Link Bandwidth
     for all "c" in the range 0 <= c <= (MaxCT-1)

> Also, I think we are in agreement that we should include an explicit
> condition in the MAM definition which constraints "SUM (Normalised
> (CTc))" (ie to make explicit the formally "implicit" constraint). Am I
> right that we agree on that?

Yes, we need a formula to make explicit the 'implicit' constraint (and for all the BC models, not just MAM).

> So, the only divergence seems to be that when doing the check on SUM
> (Normalised (CTc)):
> 	- you propose to use "Max Link Bandwidth"
> 	- I propose to use "Max Reservable Bandwidth"
> 
> Again this seems to be coming from different interpretations of these
> two IGP parameters. 
> Like Dimitry pointed out, to me the parameter which is meant 
> to be used for reservations is "Max Reservable Bandwidth". This what 
> I read in the IGP extension text. Also, as mentioned earlier, the TE 
> implementations that I am familiar with are currently all using "Max 
> Reservable Bandwidth" for aggregate admission control decisions and 
> not "Max Link Bandwidth".

Use of "Max Reservable Bandwidth" appears to be OK without per-CT Local Overbooking Multipliers (LOMs).  That is, when there is only *one* LOM for the entire link, then the formula you give appears to be correct:

    o SUM (Reserved (CTc)) <= Max Reservable Bandwidth, 
        for all "c" in the range 0 <= c <= (MaxCT-1)

However, this formula is incorrect for DS-TE when per-CT LOM's are used, since the above formula only reflects the Max Reservable Bandwidth for the entire link, and does not reflect the per-CT local overbooking factors.  So what formula do you suggest when per-CT LOM's are used?

The formula we suggested appears to be correct when per-CT LOM's are used:

    SUM (Reserved(CTc)/LOM(CTc)) <= Max Link Bandwidth
     for all "c" in the range 0 <= c <= (MaxCT-1)

or, equivalently:

   SUM (Normalized(CTc)) <= Max Link Bandwidth
     for all "c" in the range 0 <= c <= (MaxCT-1)

Please suggest what formula you propose for when per-CT LOM's are used, and which also reflects Max Reservable Bandwidth instead of Max Link Bandwidth.

Thanks,
Jerry