RE: IEEE 802.3 Requirements

["Michael M. Salzman" <msalzman@ibm.net>]

Hi Joe and Ed,

What I meant by novelty was the attribute of being new and different in the
market, giving us an opportunity to state new requirements.  By now, the
newness of 10 Gig is self apparent. By different I mean that qualtitatively
most users will find it reasonable to regard 10G networks as a step up from
the networks of old.  It is 3 orders of magnitude faster than the ethernet
of the early 80's.

From your and others' comments, as concerns enterprise LAN requirements, I
think I sense a consensus for the notion that:

	* we can have a PMD that requires better fiber for LAN applications
	* our link negotiation process should include some signals, waveforms and
test to assess fiber fitness

I am suspicious that these kinds of simple tests are unlikely to cover all
cases of poor performance, as we found out in the Gig arena, some of the
problems have to do with launch angles, relative positions, fiber movements,
etc.  Nevertheless, I think that a multi stage test can cover an adequate
number of cases in the field, say 80-90% of the culprits.  I also think we
can design a test mode that will be able to segregate the cases of:

	* No connectivity at all
	* Low power, low signal to noise
	* Lack of support for 10 Gig signals

Such test results will allow us to offer decisive and informative advice to
the equipment user and installer, without regard to any testing that they
might or might not have done.

Mike

> -----Original Message-----
> From: owner-stds-802-3-hssg@majordomo.ieee.org
> [mailto:owner-stds-802-3-hssg@majordomo.ieee.org]On Behalf Of Joe Gwinn
> Sent: Wednesday, May 19, 1999 08:39
> To: Chang, Edward S; msalzman@lucent.com
> Cc: stds-802-3-hssg@majordomo.ieee.org
> Subject: RE: IEEE 802.3 Requirements
>
>
>
> At 9:29 AM 99/5/19, Chang, Edward S wrote:
> [snip]
> >We do not have to worry about DMD, or very low-BW cables, which
> you agree.
> >When users has problems with bad cables, they will find out by excessive
> >errors or re-tries.  They will call field servicemen to fix for
> them.  Those
> >servicemen will understand how to identify the bad cables to be
> removed from
> >service.  All we have to do is to educate field servicemen how
> to identify
> >them.
>
> >-----Original Message-----
> >From: Michael M. Salzman [mailto:msalzman@ibm.net]
> >Sent: Wednesday, May 19, 1999 5:32 AM
> >
> >My experience is that on average no installer tests fiber for any thing
> >other than connectivity.  To imagine that these fellows will carefully
> >follow some timeconsuming and deliberate procedure to check out
> the cable is
> >wishful thinking.  You are right that DMD is an innate 'feature' of most
> >installed base fibers.  The ethernet community only recently
> discovered its
> >ubiquity and impact.  Nevertheless we can expect the vast
> unwashed masses to
> >blithely ignore any special handling and testing requirements
> untill their
> >installation fails to come up and then they will search for causes.
>
> To this (which I agree with) I would add one point:  The link startup and
> autonegotiation process should be made much fussier than needed for
> reliable communications over a link, so if the fiber isn't quite good
> enough, the link will simply fail to work (and maybe even give a
> comprehensible reason for its refusal to communicate), rather than be
> flakey.
>
> So, there would need to be at least three link failure codes, one for too
> little light, another for too little bandwidth, and one for too many bit
> errors.  Or the like.  One may see more than one of these kinds of failure
> at once, so they should be represented as independent bits in an error
> mask.  Anyway, having this kind of information will help the field
> installers and maintainers to figure out which rock to look under first.
>
> This may also be the right place to consider the issue of signal detect
> (802.3z, Clause 38.2.4) , with which we had so much fun in Gigabit
> Ethernet.
>
> Joe Gwinn
>
>
>