Ascend Archive
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Re: (ASCEND) V.90 Back channel
At 05:16 AM 10/16/98 , David A. Niblett wrote:
>About a week ago I read some discussion on the list about
>the maximum speed of the back channel for a V.90 connection.
>
>I deleted the message. If someone has it, would you please
>post it again.
>
>The part I'm concerened with is what the US allows as a maximum
>speed. I know you folks in Europe don't have our problems. A
>user of mine asked if it was possible to get anything higher
>than 28.8K. As I understood it, the theoretical speed is 33.6K,
>but none of my users get any higher than 28.8K
The back-channel speed has nothing at all to do with the old FCC
regulations. Basically V.90 spec allows for you to *optionally*
support the symbol rates that support 31200 and 33600 speeds.
Most, if not all, of the current DSP vendors decided to not
support the 33600 optional speed - citing issues with potential
interference of the upstream channel, where they are trying to
push the speed to its limit. Also, by making this back-channel
negotiation less aggressive, it's most unlikely that you will
see higher than 28800 on anything but ideal line conditions.
>Which leads me next to asking there is was/is an issue with 2.1.0
>load on a TNT, that might be causing it.
No, both MAX and TNT will see the same results. Bear in mind that it's
the client modem that requests the "56K" rates, and the server side
that requests the back-channel rates.
Kevin Smith (kevin@ascend.com)
Ascend Communications...
...where Network Solutions never end.
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