Subject: RE: [Diffserv] clarifications on new terms (draft-ietf-diffse rv-new-terms-04)

From: "Chen, Cheng" <[email-masked]>
Date: Thu, 3 May 2001 16:18:17 -0500

I agree with Kathie's explanation; and this implies that for a real netowrk
configuration, one really need to analyze the 
customer behaviour to decide how much bandwidth (or overbooking factor) is
needed to support the EF traffic collectively. 

Best Regards,

Cheng C. Chen

-----Original Message-----
From: Kathleen Nichols [mailto:[email-masked]]
Sent: Thursday, May 03, 2001 4:18 PM
To: Chen, Cheng
Cc: [email-masked]
Subject: Re: [Diffserv] clarifications on new terms
(draft-ietf-diffserv-new-terms-04)

"Chen, Cheng" wrote:
> 
> Brian,
> 
> May be I misunderstood something. let me try again.
> 
> Suppose we have 400 voice calls each requires 64 K bps,which are
classified
> as EF traffic. How many bandwidth do we need to allocated to EF service
> class? 400* 64 k or just 100*64K? Please comment on this.
> 
> Best Regards,
> Cheng C. Chen
> 

...

The answer is clearly "it depends". Primarily because you seem to be
mixing a "customer-visible service" with the configuration and
provisioning choices that might be made on a network. Note, there is
no such thing as an "EF service class". If a provider wants to handle
400 simultaneous calls that can hit 64K peak rates, then there'd
better be 400*64K bandwidth available (and some other requirements,
too).
If a provider has 400 total subscribers but knows from old style
telco work or some other observations that the likelihood of more than
100 subscriber making active calls at once is almost zero AND has some
mechanism for giving a "busy signal" if this should happen, then it's
probably just find to be able to deliver EF (as I understand it) up
to a rate of 100 * 64 kbps. But understand that the issues of how
the service to the customer looks and so on are really a level above
the diffserv tool box.

	Kathie

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