[e2e] Re: crippled Internet
David P. Reed
dpreed at reed.com
Thu Apr 19 21:50:21 PDT 2001
At 11:04 AM 4/18/01 -0400, RJ Atkinson wrote:
> It is well known that the technical limitations of
>cable modem networks include the asymmetric bandwidth
>(very limited upstream capacity, relative to downstream)
>and the shared nature of the bandwidth (more like big yellow
>Ethernet than the modern switched stuff).
Not well known (or obvious) at all. HFC systems are not your grandfather's
cable modem. You can partition downstream and upstream balance across a
wide range, especially if you use DWDM on the upstream segments, and even
more so since one can run fiber bundles for about the same cost as a single
fiber, so the upstream ends can be much fatter than local
distribution. FTTH (which is where HFC evolves eventually) is even more
flexible.
Why does a cable distribution system have to remain hierarchical? Already
lots of systems have cross links for redundancy in case the upstream cables
are cut.
- David
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