Last Mile QoS WAS: RE: QOS or more bandwidth

Pete Kruckenberg pete at
Tue May 29 20:23:09 UTC 2001

On Tue, 29 May 2001, Nathan Stratton wrote:

> On Tue, 29 May 2001, Pete Kruckenberg wrote:
> > A 1536-byte frame has a fairly significant impact (~8ms) at
> > 1.5Mb/s. QoS appears to have diminishing return as you move
> > beyond 45Mbps, at least as far as multi-service networks go.
> > Maybe QoS isn't necessary or useful in the core if you have
> > line-speed switching and no congestion on an OC-X/DWDM
> > network.
> It has even a larger impact on a 128K frac T1 (~93ms).
> QoS is a big help, but at slower speeds you also need to
> deal with fragmentation and the layer 2 transport. I am
> surprised that there has been so little movement as far
> as QoS and efficiency in regards to VoIP. Take a

Because VoIP is mostly being deployed in the enterprise and
at the core of the LD network.

I am surprised with all of the CLEC's a few years ago who
were deploying IP "Soft Switches" that had VoIP
capabilities, I don't know of anyone selling VoIP services
over DSL (which seem like at least one way to break into the
local voice market).

Sprint initially focused ION on selling user-configured
on-demand residential services over DSL, and were drivers
for VoIP improvements at sub-T1 speeds, but I guess that
didn't make it (the ION presentation at N+I looked
completely unrelated).

I'd guess the financial driver for the last mile now is
pretty much the phone company (who now also owns the cable
company and the competitive phone company as well as the DSL
company). I don't see what motivation they would have to run
multiple services on the same line, and QoS just doesn't
seem to fit in the same phrase as "phone company" (or "cable
company"). Biggest driver for the last mile: support your
local community network, or start one with your neighbors.


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