My understanding is as follows:
1. Lucent dropped the 40K upload and 45K-sync mode features of V.flex2
in order to make it easier to get Rockwell to in interoperable level
faster. K56flex 1.1 does not have these features. It is PCM download and
V.34 uploads. However, what I've heard is that going forward they do want
to reintroduce these abilities over time. And that they are also bringing
them to the table for the ITU-T work. So maybe in V.PCM or whatever it is.
2. I too have seen claims that they can get 56K downloads without violating
the FCC power limitations. At InterOp a person in the Lucent booth was
saying they can go even higher - 61K in Europe where they don't have the
power limits and the lines are mostly 64K clean. But in real world situations
I haven't seen it happening. Maybe in a lab with perfect lines it is possible
to get it, but I don't think we're going to be seeing 56K downloads in the
real world. Personally I think 48K-50K is going to be the high end, with
some 52K links in good areas, *maybe* even 54K (K56flex goes in 2K blocks).
But that's my personal view.
>either of these two options? Also, from what I understand, the 56k
>download speed will result in a slower-than 33.6 upload speed, does anyone
>have a list of upload/download speeds which the K56 protocol supports?
Upload is V.34bis. Officially it goes up to 33.6K. I think the low-end
is 2400bps. Fairly standard, just like today's modems.
Download has the V.34bis capabilities too if a PCM connection fails. If
PCM negotiation succeeds then it is 56K and down in 2K incriments. I'm
not sure what happens if, say, it gets down to 32K. I don't think it can
shift from PCM to V.34 mode on the fly - I think it just stays in PCM.
Marty?
I will say that in testing, and in reading the USR and Ascend lists, as
well as lists like inet-access, it does look like uplink speeds are hit when
the downlink speeds are high. 31.2K and 28.8K uplink seems common when the
downlink is running in PCM mode. But some still do see 33.6K.
-MZ
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