RE: (PMOD) USR 33.6 connection problems.

mail2news-portmaster-modems@csulb.edu
1 Oct 1999 14:34:27 GMT

In article <1EFF34E84F5FD31197E900A0C99DD6AB5D9C69@auntbea.twtelecom.com>,
Bruce.Farnham@twtelecom.com says...
>
>SLIC uses a signalling protocol called "robbed bit" which robs every sixth
>T-1 frame of the least significant bit to be used for call setup and
>teardown.
>This translates to lower data rates. If the ISP is also on a facility (T-1)
>that
>uses the robbed bit scheme, it is likely that data rates would be
>significantly
>impaired.
>
>Bruce Farnham
>Time Warner Telecom
>Technical Support - Switching

Isn't that SLC (Subscriber Line Card) instead of SLIC? Robbed-bit
signalling can be used in absence of SLC's. My local GTE CLEC uses
GDT5 switches which are configured with robbed-bit signalling.

Robbed-bit signalling has minimal impact on modem throughput. Look
through the archives of comp.dcom.modems and comp.dcom.telecom.tech.
I've seen several users connect to our PM3 pool at 52K and many
above 50K. V.90 has a theoretical max of 56K precisely because of
the robbed bit; otherwise it could achieve 64K.

--matt

+------------------------------(c) 1999 Matthew Black, all rights reserved--
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