RE: Network Traffic Violations

[Matthew Gast <gast () iprg nokia com>]

At 02:41 PM 9/10/98 -0600, you wrote:
> Telco-ISP's will survive because the provide the same 
> bandwidth to each user regardless of how many users
> in your area are using the service.  I think you'll
> find that cable modems, you are sharing bandwidth
> with all the other houses in your area.  

That's actually not true--DSL service also shares bandwidth:

home <-> DSL line <-> DSL access multiplexer <-> regional ATM net run by
telco or other common carrier <-> your ISP <-> Internet

With low-end DSL service, traffic over the regional ATM net is sent at the
lowest possible priority (UBR--Unspecified Bit Rate, or "Please Drop Me on
the Floor if You've Oversubscribed Your Cell Cloud").  One could possibly
construe this as sharing bandwidth with your entire geographic region, like
the San Francisco Bay Area.  Unfortunately, the technology used by ATM or
Frame Relay to implement QoS also lends itself to oversubscribing the
capacity, and perhaps using the poor performance to extort more money for
guaranteed bandwidth.  One argument I've seen used to push telcos towards
adopting DSL is that they can have tiered pricing based on guaranteed
bandwidth over the ATM cloud.

Is anybody familiar enough with cable modems to know how large an area
you're sharing bandwidth over?  If it's only a block or an apartment
complex or something relatively small, the impact of oversubscription could
be smaller than with DSL.

        --Matthew

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Customer Support Engineer    support fax:       408-743-5680

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