Ascend Archive
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Re: (ASCEND) Am I the only one ?? (fwd)
Once upon a time Gary Stern shaped the electrons to say...
>>But... why shouldn't none of our MAXes connect at 31200 upstream? As i've
>>said, it NEVER happened. It's always 28.8K. I think it could at least *TRY*
Just because. With PCM it means you're one notch from the best, and PCM
puts some unique load on the lines and the switch codec, so even if it
normally hits 33.6K with V.34 you're limited to 31.2K with K56flex (Not
sure on V.90), and perhaps taken down a notch by a codec limitation or the
like.
>Now I don't want to get into the hard technicalities (and I dont
>fully understand them :-) but I am sure there is a good reason for it
>which will make sense in the long run, I really would like to see
>MegaZone's comments on the matter if he makes any :-)
K56flex and X2 both disabled the higher symbol rates on the upstream,
meaning 31.2K was the max they'd do when in PCM mode. I don't know if this
has carried over into V.90 or not. This was not a NA only thing - it was
for the world. The higher symbol rates created some kind of interference
problem (ok, I'm not a signalling person, that's about as far as I took it)
with the PCM downstream, so it was dropped to improve the downstream speed.
>session time without dropping out, I got him to set his +MS=56 to a
>maximum of 40000 and dialin again, his reverse speed was 28800, the
The speed itself isn't so much an issue, as that PCM is being used. If
K56flex/X2 (and again, I'm note *sure* but I believe V.90) is used then you
will not get 33.6K upstream - 31.2K is the maximum the enabled symbol table
will support. 28.8K being the second. Unless Rockwell did K56flex different
from Lucent - that as Lucent's limitation in their K56flex and my understanding
was that it was part of the spec, so it should be the same.
-MZ
--
<URL:mailto:megazone@megazone.org> Gweep, Discordian, Author, Engineer, me..
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