Re: [Diffserv-interest] congestion in diffserv network

["Feng Y" <feng6 at uwindsor.ca>]

Hi Brian, 

Could you please explain "each of them retains the
statistical properties of a single Internet"? What are the
properites? Do you mean when the network defines the
Diffserv classes,suppose for AF4 class, they may have
different values for the same parameters such as CIR, EBS?
Or even some of the networks does not have class AF4 but
have class gold, silver, and bronze instead?

Thanks

Yang

On Wed, 29 Oct 2003 12:07:02 +0100
 Brian E Carpenter <brc at zurich.ibm.com> wrote:
> Another way to look at it is that what diffserv does is
> split the network
> into several separate networks, but each of them retains
> the statistical
> properties of a single Internet.
> 
>    Brian
> 
> John Schnizlein wrote:
> > 
> > The simple reason that congestion can occur is that the
> TCA
> > need not limit incoming traffic sufficiently to avoid
> it.
> > The TCA for expedited forwarding is the only one, of
> many
> > traffic classes, that seeks to eliminate potential
> congestion,
> > in order to minimize delay and jitter.
> > 
> > The parameters of other class definitions, assured
> forwarding
> > for example, are intended to mark traffic at different
> ingress
> > rates for different treatment when congestion occurs.
> Note
> > that this anticipates that congestion will occur.
> > 
> > Please recall that the high link utilization in an IP
> network
> > is obtained in large measure because traffic loads are
> high
> > enough to produce occasional congestion. Cooperative
> management
> > of this congestion is the responsibility of
> transport-layer
> > protocols.
> > 
> > John
> > 
> > At 10:43 AM 10/28/2003, Feng Y wrote:
> > >... I wonder why the
> > >overloading or even congestion occurs in diffserv
> network.
> > >In diffserv architecture, the ?DS ingress node is
> > >responsible for ensuring that the traffic entering the
> DS
> > >domain conforms to any traffic conditioning agreement
> (TCA)
> > >between it and the other domain to which the ingress
> node
> > >is connected? [RFC 2475]. Moreover,   ?Traffic
> conditioning
> > >performs metering, shaping, policing and/or re-marking
> to
> > >ensure that the traffic entering the DS domain
> conforms to
> > >the rules specified in the TCA, in accordance with the
> > >domain's service provisioning policy?. So what causes
> the
> > >overloading or congestion in diffserv? Does anyone
> explain
> > >it for me or give me some references. Thanks in
> advance.
> > 
> > _______________________________________________
> > Diffserv-interest mailing list
> > Diffserv-interest at ietf.org
> >
> https://www1.ietf.org/mailman/listinfo/diffserv-interest
> 
> -- 
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
> - - - -
> Brian E Carpenter 
> Distinguished Engineer, Internet Standards & Technology,
> IBM 
> 
> NEW ADDRESS <brc at zurich.ibm.com> PLEASE UPDATE ADDRESS
> BOOK


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