Subject: Throughput specifications

From: [email-masked] (Luca Lombardi)
Date: Thu, 16 May 1996 18:00:40 +0200

Hi. Forgive me if I'm not precise in the following, or if I say something
that has been already discussed in the int-serv WG.
It is clear that the variety of proposals for service classes in the Internet 
has aimed at the satisfaction of a broad spectrum of user needs: e.g., 
guaranteed service for "untolerant" real-time applications, predictive service 
for "tolerant" real-time applications, etc. I think that in such an environment 
there can be also a need for a service class which allows users to specify a QoSrequest about achieved throughput; i.e., a certain amount of data to be 
transferred over a certain time interval. It seems to me that this doesn't map 
easily to a specification about the delay of single IP packets. As for I know,
such ideas are not new in the Internet community. I should like to know your 
opinion and your comments.
Thanks in advance.
     
                   Luca Lombardi

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From: Juha Heinanen <[email-masked]>
Date: Thu, 16 May 1996 23:06:31 +0300

I think that in such an environment there can be also a need for a
   service class which allows users to specify a QoSrequest about
   achieved throughput; i.e., a certain amount of data to be transferred
   over a certain time interval. 

see draft-heinanen-pbe-svc-01.txt.

-- juha

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From: Craig Partridge <[email-masked]>
Date: Thu, 16 May 96 13:12:27 -0700

I think that in such an environment 
    there can be also a need for a service class which allows users to specify 
   a QoSrequest about achieved throughput; i.e., a certain amount of data to be
    transferred over a certain time interval.

    It seems to me that this doesn't map 
    easily to a specification about the delay of single IP packets.

Actually it does.  For instance, the guaranteed specification says that
someone emitting a stream of data (within the guaranteed QoS parameters)
will, for any individual packet, see a delay of no more than X.

If you send 12 packets (and assuming they meet the advertised QoS), each
will see a delay of no more than X.  So you can compute the overall delay
by simply computing:

    (a) how long, according to the QoS rules, it will take to be allowed to
    place the 12 packets into the network

    (b) the guaranteed delay X

and adding the two results.

Another, perhaps simpler, way to express this point is that delay and bandwidth
(which is data over a time interval) are simply duals of each other.  Given
a certain amount of data you want to send and a target value for either delay
or bandwidth, you can compute the other value.

Craig