Re: [802.3ae] RE: [802.3ae_Serial] 802.3ae PRBSs are upside down
pat_thaler@xxxxxxxxxxx wrote:
> The only question is whether to use the current pattern or to invert it. My
> reading of O.150 is that it implies the inverted pattern is used, but it
> doesn't state it and some parts of the spec appear to say that either
> inverted or normal might be used for a given pattern. Inverted and
> non-inverted should perform an equally effective test. The concern with
> inverting the signal is that people are trying to get these chips done and
> implementations under way will end up with the wrong polarity. It would be
> helpful if someone could verify whether BERT testers support both polarities
> or just one.
Thanks Pat. This is really the crux of the issue - should we mandate use
of the inverter to make the 10GE standard more compatible with existing
test equipment.
I don't represent a test equipment provider, but I'll start the dialogue in
order to gauge whether to invert the PRBS31 generator.
For bit based BERTs (i.e. those testers for which you program every bit)
it is irrelevant.
For Pattern based BERTs (i.e. testers pre-program with varying length
PRBS streams) most specify the O.150 as the standard pattern and
allow the "inverted" option (which from the discussion actually removes
the inverter we're considering installing). There may be some testers
in this group which only look for the O.150 pattern.
For Network based BERTs (i.e. those testers which are designed to
test the optical stream in a network application) most specify O.150
compatibility. For more details on this, you can try a YAHOO search
using the key words "O.150 PRBS MEASUREMENT" (although
there are other equally applicable searches).
So I'm looking for feedback. Who has used test equipment which only
accepts O.150 format PRBS. What are other test equipment providers
recommending.
N.B. We still have to discuss the WIS test pattern, I'd prefer to do this
in a separate thread.
--
Tim Warland P. Eng.
Applications Engineer
Quake Technologies (613)270-8113 ext 2311
Tough Times don't last, tough people do