The MPLS WG Archive

["Erickson Trejo-Reyes" <eenet@electeng.leeds.ac.uk>]

Mr Chen,

 

No, I certainly don't know if there is any document that speaks of the subject. I would certainly try to find something in the literature, and yes, I agree with you that having others' impressions of this would be rather constructive. Thanks for your answer and we'll keep in touch.

 

 

Best regards,

 

 

Erickson Trejo

 

-----Original Message-----
From: C. Chen <cchen@asl.dl.nec.com>
To: Erickson Trejo-Reyes <eenet@electeng.leeds.ac.uk>
Cc: curtis@avici.com <curtis@avici.com>; david.charlap@marconi.com <david.charlap@marconi.com>; mpls@UU.NET <mpls@UU.NET>
Date: Monday, August 28, 2000 9:51 PM
Subject: Re: Fw: MPLS and CAC

Mr.  Erickson,

It seems to me that overbooking factor determination is not simply PCR * activity factor (e.g., .4). I was wondering wether there is a IETF draft defining overbooking factor that you know of ? If not, I would like to suggest that we work together with people who might be interested in participating to make a draft contribution on this suject.
 

Best Regards,
 
 

Cheng C. Chen
 

Erickson Trejo-Reyes wrote:

>  Thank you both David and Curtis for your kind answers. Refering the 
>     following statement in the possible configuration: > 
>     While CAC is fully supported it can essentially be ignored by setting a very 
>     high overbooking factor... > With the high overbooking, these 
>     tunnels come up anyway.  If there are preferred services, they get 
>     preferred treatment so the overbooking doesn't matter to them.  Best 
>     effort services temporarily get squeezed... therefore oversubscribing is 
>     much more preferrable to having CAC kick in and losing 100% of the traffic 
>     until things settle down. By overbooking you mean that, for example, if a 
>     voice source can be treated as a VBR source with 64 KB peak bit rate and 
>     activity factor of 0.4, then the reservation should be made to a higher 
>     value than the computed effective bandwidth (and obviously higher than the 
>     average bit rate of 0.4 times 64KB)? I had thought that, if an MPLS node 
>     is due to use only certain percentage of its total capacity to serve, for 
>     example, guaranteed services, it would not be too harmful to make 
>     reservations (up to the available percentage) only based on the sustained 
>     rate, with the only possible consequence of temporary squeezing the 
>     throughput of best-effort services. Comments? Again, thanks in 
>     advanced,  Erickson