[c-nsp] GigE woes

[Tim Durack]

On Mon, May 17, 2010 at 12:31 PM,  <tkapela at gmail.com> wrote:
> Tim,
>
> Assuming the Rx counters on your side(s) are all zeros, then we could move to consider perhaps their equipment has a layer 1.5 or PLCP issue -- failing to transport small and non-line-rate frames could be related to:

What is PLCP?

> -slightly broken Rx pll or ifg detection in their rx path; whereby it locks "better" for longer/more frequent payloads than it will for small.
>
> -"near Rx threshold condition" at the receiver on either side of your link, whereby FEC and block interleave codes "fail" with smaller frames, but can operate with larger, low entropy data.

That's the kind of information I'm looking for.

> Since this case is so odd, I also suggest you try ping with more "random" data -- ascii doesn't really involve that many bits in each byte. Perhaps this can tease out further detail after testing whether payload content has any bearing on success.

Having a hard time coming up with a convincing test, especially with
test sets targetted at linerate rather than low bitrate tests. Haven't
tried varying patterns yet. Maybe that will turn something over.

Thanks,

-- 
Tim:>