Re: DS-TE Requirements - input sought on "Overbooking"

[Marc Binderberger <marc@sniff.de>]

Hello,


>> Considering a DS-TE solution which allows to enforce different 
>> overbooking
>> ratios for different Classes of Service, are there Network Operators out
>> there (I repeat *Network Operators*) who have a specific requirement for
>> enforcing different values for these per-COS overbooking ratios in
>> different parts of the network ?
> 	[...]
> So, Network Operators - to rephrase the question:
>
> Is there a need for per-COS and per-Link based overbooking which requires
> protocol hooks for advertising out per-COS, per-Link overbooking factors?

Without the "and":

Overbooking per CoS? Yes.

I want to overbook data services but don't want to overbook real-time 
services.


Overbooking per link? Not really.

 From my ATM colleagues I picked up some discussion about a different 
overbooking factor on a few links. Have to ask for the "why". A motivation 
could be to "squeeze" a particular link to delay a costly upgrade but 
remain with no/low overbooking on the network in general to make life 
(read: fulfilling SLAs) easy.
(But not a motivation for protocol designers I guess)


Some comments:

(i) Today ISIS/OSPF transports the Max Reservable bandwidth and the 
unreserved Bandwidth (per priority) per link which gives us a per-link 
overbooking capability already.

(ii) with global overbooking ratio per CoS it is just a matter of how much 
bandwidth I reserve for my TE-tunnel per CoS. When overbooking data by 4 
but not overbooking voice I reserve bw/4 for data and bw' for voice. So no 
need for per-link ratios.


Regards, Marc
--
Marc Binderberger          <marc@sniff.de>          Frankfurt/Germany