Re: MCI [ATM overhead]

[Wolfgang Henke <wolfgang () whnet com>]

johnc () msc edu (John Cavanaugh) writes:
> You can find a paper that addresses this question at
>     
>    http://www.msci.magic.net/docs/magic/overhead.ps or
>    fte:ftp.magic.net/pub/magic/overhead.ps
>     
> It covers OC-3c, OC-12c, 100 and 140 Mbps TAXI, and DS3 framing, and
> gives the effective bandwidth at each layer.

Thank you for the reference. I will certainly check it out. Here is a 
little table which I hope will help ISPs planning to upgrade bandwidth:


SONET (Synchronous Optical Network) speeds given in Mbps

                nominal   w/o Sonet  ATM   TCP/IP
                          overhead

OC-3   STS-3c   155.520     149      122     137   future net backbone

OC-12  STS-12c  622.080     599      488     549

OC-48  STS-48c  2488.32    2396     1953    2197   current telco backbone

OC-192 STS-192c 9953.28    9585     7813    8788

on single mode fiber
or multi mode fiber
or CATV 75 ohm coax (the lower speeds)

Additions and corrections are welcome. 
Wed Mar 20 07:56:41 PST 1996
http://www.whnet.com/wolfgang/sonet.html

>     John Cavanaugh                              EMail: johnc () msc edu
>     Minnesota Supercomputer Center, Inc.               johnc () cray com
>     1200 Washington Ave. S                      Phone: +1 612 337-3556
>     Minneapolis, MN  55415                      FAX:   +1 612 337-3400


Wolfgang


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