Re: Data rate standards vs internal switching standards
Roy,
I was hoping for a YES/NO answer on whether a variable IPG
over a 10Gbps is acceptable to you.
Let me answer your questions and re-submit the question.
Ariel
> Date: Wed, 04 Aug 1999 14:49:45 -0400 (EDT)
> From: Roy Bynum <RBYNUM/0004245935@xxxxxxxxxxx>
> Subject: Re: Data rate standards vs internal switching standards
> To: Ariel Hendel <Ariel.Hendel@xxxxxxxxxxx>, stds-802-3-hssg <stds-802-3-hssg@xxxxxxxx>
> Content-transfer-encoding: 7BIT
>
> Ariel,
>
> Where would the additional bytes of the variable IPG originate?
The MAC.
> Where would they go?
To the PHY.
(If you want to send them across OC-192 or not that is your prerrogative).
> What would happen to them between the MAC and the PHY?
Nothing. They just go.
> What happens when the MAC at 10.0 gb is operationally overloaded?
There is no transmit resource in 802.3 that can become overloaded.
Queuing is not part of the MAC layer model.
> How do you tell that the PHY is operationally overloaded beyond 9.584
> gb?
Will not happen. The variable IPG is there to limit the rate to 9.584.
> How would you tell the difference? Is there any difference?
>
> Would not putting a limit on effective transfer rate at the MAC by the
> PHY be the same as putting the limit on the MAC to start with? I
> personally can not see any difference, except that you loose
> visibility of the start of overloading conditions at the network
> management level.
>
...
>
> Date: Wed Aug 04, 1999 11:12 am CST
> Source-Date: Wed, 04 Aug 1999 10:11:26 -0700 (PDT)
> From: Ariel Hendel
> EMS: INTERNET / MCI ID: 376-5414
> MBX: Ariel.Hendel@xxxxxxxxxxx
>
> TO: Ariel.Hendel
> EMS: INTERNET / MCI ID: 376-5414
> MBX: Ariel.Hendel@xxxxxxxxxxx
> TO: stds-802-3-hssg
> EMS: INTERNET / MCI ID: 376-5414
> MBX: stds-802-3-hssg@xxxxxxxx
> TO: * ROY BYNUM / MCI ID: 424-5935
> Subject: Re: Data rate standards vs internal switching standards
> Message-Id: 99080417120456/INTERNETGWDN1IG
> Source-Msg-Id: <199908041712.KAA03822@xxxxxxxxxxxxxxxxx>
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>
> > Date: Wed, 04 Aug 1999 10:19:28 -0400 (EDT)
> > From: Roy Bynum <RBYNUM/0004245935@xxxxxxxxxxx>
> > Subject: Re: Data rate standards vs internal switching standards
> > To: Ariel Hendel <Ariel.Hendel@xxxxxxxxxxx>, stds-802-3-hssg
> <stds-802-3-hssg@xxxxxxxx>
> >
> > Ariel,
> >
> > Actually, I am not in favor of a programmable IPG. I think that the IPG
> > should be set to minimum for all frames in full duplex 10GbE. With 400
> > bytes as the current average size of Internet 802.3 frames, I don't
> > think that there will be enough "slop" to make up the difference
> > between a 10.0 gb MAC and a 9.584 gb PHY. In the future, with more
> > and more video based applications, the average size of the data frame
> > will be increasing. This will only cause the MAC buffer discard rate
> > to increase if the MAC and PHY are not data rate matched. I would much
> > rather see the data rate be defined at the MAC, not the PHY.
> >
>
> My apologies for being dense on this thread, just one last hypothetical
> question for Roy.
>
> Would you accept a 10Gbps rate along with a variable IPG?
> The IPG is just simple function of the length of the last packet sent
> to guarantee that the payload rate does not exceed your OC-192 rate.
>
> Open loop, interoperable, no pins, no thresholds, no nothing.
>
> Would you settle for that or you still prefer the 9.xyz rate?
>
>
>
> Thanks,
>
>
> Ariel
>