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RE: [RPRWG] RE: [IPORPR] payload length and padding and stuff




Anoop,

I agree with you that the draft is vague on this.
One way to approach this could be as follows:

Specify that a RPR MAC has only ONE reconciliation
layer. The service primitives can specify direction.
As a consequence, no node can have different PHYs on the east and west
therefore it is not possible to build a ring with any other phy.

raj


> -----Original Message-----
> From: Anoop Ghanwani [mailto:anoop@xxxxxxxxxxxxxx]
> 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
>  
>