Subject: WG: [Diffserv] about the concern of a rate loss in the definitio n ofdraft-charny-ef-definition-00

From: [email-masked]
Date: Thu, 10 Aug 2000 13:12:09 +0200

Jon,

>> So lets suggest the following modification for an explicitly 
>> measureable EF definition:
>> 
>> Let R be the bit rate in bits/s and B the buffer size in 
>> bits. An EF PHB (R,B) is given if the given DS aggregate 
>> at the output link (or arriving  downstream node)
>> can pass through the Leaky Bucket (R, B)and B(0)=0 without 
>> loss of bits. R is the guaranteed bit rate and 
>> B the jitter bound.

>Under this definition as long as a router does not drop any 
>packets it can delay them for as long as it wants, putting
>arbitrarily large gaps in the output packet stream. This
>would not seem to be form of behavior desired for the EF PHB.

Right. Thanks for pointing out this. EF PHB should somehow to sustain
the promised rate even if a lasting pause follows the last packet.
Lets add the following:

... If buffer content size B(k) at time k becomes zero,
there must be no to be departed packet of the aggregate remaining in the node.

At least this still seems to be measureable.

Regards,

Xiaoning   

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