RE: [RPRWG] Gandalf - question on Framing
Hi all,
in my view both Gandalf and Alladin frame formats fits in our criteria.
- They allow a 'simple' mapping of Ethernet frames by putting the
common .3 and .17 fields (DA, SA and Type) in the same order
- They define a new MAC frame format
Having an HEC that covers all the RPR header (including DA and SA) is
very useful because allows cut-through nodes not delivering frames to
the wrong destination and this feature is very important in a
carrier-grade metro network. Both Allading and Gandalf are now aligned
on this issue.
Having the Ethernet based frame with the Type field saying that we are
carrying RPR means, IMO, that we are building a ring-oriented switching
technology on top of point-to-point Ethernet MACs.
This is not what we are doing according to our 5 criterias and PAR, as
Mike said. Both Allading and Gandalf are aligned on this issue.
The only difference is that while Gandalf puts the RPR specific fields
before the DA, SA and Type, Alladin does it after them.
Italo
> -----Original Message-----
> From: sayandeh@xxxxxxxxxx [mailto:sayandeh@xxxxxxxxxx]
> Sent: Monday, December 03, 2001 5:28 PM
> To: tak@xxxxxxxxx
> Cc: sayandeh@xxxxxxxxxx; pkj@xxxxxxxxxxx; stds-802-17@xxxxxxxx
> Subject: Re: [RPRWG] Gandalf - question on Framing
>
>
> Mike
>
> The point you raise about violating the 5 criteria is not
> quite clear. Which criteria
> is violated? Criteria 2 on compatibility states that RPR
> frame "format will allow for
> a SIMPLE mapping for 802.3 frames into RPR frames and vise
> versa". Now what is
> simpler than a null mapping (i.e. just augmenting).
>
> The distinct identity criteria lists:
> - bandwidth management
> - high speed rings (>OC-12)
> - sub 50 [ms] protection
> - & frame size greater than 1518 [bytes]
>
> Again no reference to framing as being the unique feature.
>
> Furthermore it is still not clear why one approach is better
> than the other. If I
> understand you correctly, either approach would do, but one
> is more politically
> correct.
>
> Regards, Siamack
>
>
> > Ethernet Frame Design:
> > ----------------------
> >
> > Consider if the RPR frame is exactly the Ethernet frame with the RPR
> > details placed after a TYPE field and the FCS covering exactly
> > what the Ethernet FCS covers. If so, we violate our 5 critera
> > and should recind our PAR or dot3 would do it for us. This
> > is because it violates the uniqueness requirement. It also
> > pushes us into 802.1 territory, since these techiques could
> > be applicable to all MACs, since a new type was defined.
> >
> > Every meeting I am up there reminding people that 802.3 had
> > serious concerns about our group intruding into their
> > space. Use of the Ethernet frame is absolutely un-acceptable
> > in my technical and politcal opinion.
>
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