Re: [RPRWG] More comments on preemption
Raman,
Thanks for your correct interpretation.
L1 agnostic is an important factor here.
William Dai
----- Original Message -----
From: "Raman Venkataraman" <kvraman@xxxxxxxxxxxxxxxx>
To: "Devendra Tripathi" <tripathi@xxxxxxxxxxxx>;
<jeanlou.dupont@xxxxxxxxxxx>
Cc: "William Dai" <wdai@xxxxxxxxxxxx>; <stds-802-17@xxxxxxxx>
Sent: Friday, May 04, 2001 7:13 AM
Subject: Re: [RPRWG] More comments on preemption
>
> Hi,
> My understanding of William's proposal for the IDLE/Escape marking is
> in the 802.17 MAC level and it is not clear to me why PCS layer is getting
> involved.
> It looks to me that if we use the POS transport, the special ESC sequence
> can be
> used for detecting the special markings. However, if we use the GFP for
the
> transport,
> the escape sequences will be stripped before encapsulating the packets
into
> the GFP.
> So, it looks like this method will work if we use the POS.
> Regards
> Raman
> ----- Original Message -----
> From: Devendra Tripathi <tripathi@xxxxxxxxxxxx>
> To: <jeanlou.dupont@xxxxxxxxxxx>
> Cc: William Dai <wdai@xxxxxxxxxxxx>; <stds-802-17@xxxxxxxx>
> Sent: Thursday, May 03, 2001 6:17 PM
> Subject: RE: [RPRWG] More comments on preemption
>
>
> >
> > Hi William,
> >
> > Actually, it is not just a question of symbol. The PCS layer of 1/10 G
> > Ethernet
> > PHY makes quite a few assumtions on where an IDLE can come. IDLE is also
> > used to decide on clock compensation. In all likelyhood such a packet
will
> > be declared erroneous ( I need to look this more seriously to be
> > conclusive).
> > If we decide to use the reserve symbol to mark Escape, there may be
> > compatibility (of PHY devices) issues.
> >
> > The other issue is related to frame format change at gateway (LAN/MAN)
> > points.
> > The default understanding which I had was that when a Packet from LAN
> comes
> > to
> > Metro area, it requires add/delete of header and that is about it (as
> > for as frame format is concerned). But this may not be strong issue
> though.
> >
> > Regards,
> > Devendra Tripathi
> > VidyaWeb Inc.
> > Pune, India
> > Tel: +91-20-433-1362
> >
> > > -----Original Message-----
> > > From: jeanlou.dupont@xxxxxxxxxxx [mailto:jeanlou.dupont@xxxxxxxxxxx]
> > > Sent: Friday, May 04, 2001 4:53 AM
> > > To: Devendra Tripathi
> > > Cc: William Dai; stds-802-17@xxxxxxxx
> > > Subject: RE: [RPRWG] More comments on preemption
> > >
> > >
> > >
> > >
> > >
> > > Could you clarify your statement "... definitely takes us away
> > > from Ethernet"?
> > >
> > > If you are targeting your comment at the Ethernet PHY layer: the
> > > Ethernet (100
> > > & 1000) uses 8B/10B encoding.
> > > There are some "spare symbols" not used (if I am not mistaken)
> > > that could be
> > > redefined to mean "IDLE/Escape".
> > >
> > > Jean-Lou Dupont
> > > Marconi Networks.
> > >
> > >
> > >
> > >
> > >
> > >
> > > To: "William Dai" <wdai@xxxxxxxxxxxx>, stds-802-17@xxxxxxxx
> > > cc: (bcc: Jeanlou Dupont/MAIN/MC1)
> > >
> > > Subject: RE: [RPRWG] More comments on preemption
> > >
> > >
> > >
> > >
> > >
> > > > 3. Each M and L packet transfer will be inserted an "IDLE/Escape"
> > > > word for every 256 byte (for the sake of alignment/padding
> concern)
> > > > as the preemptive insertion point.
> > >
> > > This is very good idea to manage pre-emption and other QOS related
> > > considerations but this definitely takes us away from Ethernet.
> > >
> > > Regards,
> > > Devendra Tripathi
> > > VidyaWeb Inc
> > >
> > >
> > >
> > >
> > >
> > >
> >
>
>