RE: [RPRWG] RE: [IPORPR] payload length and padding and stuff
Actually, basic data rate may not be an issue here as one can suitable
slowdown the 10G to match OC192 rate (there is protocol defined in 10G for
that). The device which will interface to two different media should take
care of translation of frames to and from the different media. Accordingly a
frame from Sonet (which could be <64 bytes to ~64KB long) may need be
sliced/padded into packets of suitable sizes. If there is stream of small (<
64B) packets, naturally the effective data rate on 10G will go down
significantly and in that case one will have to resort to some sort of flow
control.
However, I agree with Anup that we should keep the standard based on uniform
media. Any mixing of media should be left to bridges.
Regards,
Devendra.
> -----Original Message-----
> From: owner-stds-802-17@xxxxxxxxxxxxxxxxxx
> [mailto:owner-stds-802-17@xxxxxxxxxxxxxxxxxx]On Behalf Of Anoop Ghanwani
> Sent: Tuesday, December 03, 2002 4:03 PM
> To: 'Frank Kastenholz'; iporpr@xxxxxxxx; 'stds-802-17@xxxxxxxx'
> Subject: [RPRWG] RE: [IPORPR] payload length and padding and stuff
>
>
>
> Frank,
>
> We shouldn't be trying to mix different PHYs,
> e.g. 10GE and OC-192, since they are in fact running
> at different data rates, and having PHYs with different
> data rates on the same ring is not allowed by the
> current version of the draft. I think the draft
> is silent on this specific issue, though.
>
> I'm cc.-ing the 802.17 list since this is an interesting
> issue that has come up there as well. Maybe someone
> else might be able to shed some light on this
> (PHY people??).
>
> -Anoop
>
> > -----Original Message-----
> > From: Frank Kastenholz [mailto:fkastenholz@xxxxxxxxxxx]
> > Sent: Tuesday, December 03, 2002 3:46 PM
> > To: iporpr@xxxxxxxx
> > Subject: [IPORPR] payload length and padding and stuff
> >
> >
> > i'm editing the iporpr document and have come across a question...
> >
> > suppose i have an 802.17 ring comprised of both gig-e and sonet
> > sections. gig-e, i assume, has the usual ethernet min frame
> > size rules, so if a dataframe is transmitted onto gig-e and
> > the payload is too short, it gets padded so that the frame
> > is 64 bytes. if a frame is transmitted onto a sonet section,
> > no such padding is needed, since there are no min frame length
> > rules for sonet. so what happens when a frame that was initially
> > transmitted on a sonet section reaches a gig-e section of
> > the ring:
> >
> > +-----------+ +-----------+ +-----------+
> > | Station 1 | | Station 2 | | Station 3 |
> > +-----------+ +-----------+ +-----------+
> > / \ / \ / \
> > ...___/ \________/ \________/ \___...
> > sonet gig-e
> >
> > A frame generated at station-1 that has, let's say, only a 20 byte
> > payload, would be 42 bytes long. This is fine for sonet. What
> > happens when the frame reaches the gig-e section between stations 2
> > and 3?
> > - is the frame padded by the mac/phy layers in station 2?
> > - is the frame dropped?
> > - are the min-frame rules dropped for gig-e when it's being used
> > for .17?
> > - is it illegal to mix sonet and gig-e in the same ring?
> > - am i very confused and is the answer obvious to all but me?
> >
> > thanks
> >
> > frank kastenholz
>
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