Cable Modem [really good network design]

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1

> The Ethernet protocol was designed to adjudicate and route packets
> internal to one homogeneous, physical network. It handles media
> access, security, reliablity and routing in that one physical network.

What does Ethernet have to do with routing ?

Routing in its original sense. You stick an Ethernet frame in here,
it traverses a number wires connected by boxes which make decisions as
to which wire it should go out on. It then pops out on the other edge
of the network. Magic!

A network of Ethernet switches looks a heck of a lot like routers.
They are certainly smarter than the IP routers of circa 1983.

The problem you dont really have one physical network. We are trying
to extend Ethernet into a logical network.

Who is "we" in this statement?

The
reason that I like PPPoATM is that the end device requires littel
intelligence , it knows one PVC, and all changes (linking them to the
ISP of choice, propogate easily downstream)

Little intelligence to implement ATM? Never heard that claim before.

Contrast the cost of an Ethernet chip with an ATM chipset.

.RFC 1483 (Ethernet over
ATM, used in DSL and plausibly in cable ) is a great idea for business
but not suitable for home users. Hardware that you speak of becomes
just too expensive.

Define "great idea". Compare and contrast with all the failed DSL
providers which used ATM. Use one DSL/ATM provider who is making money as
an example. No excuses please.

How do you reconcile the cost of the hardware being too expensive with
the statement above that ATM requires little intelligence?

It appears as if someone has thought of this before Someone is apparently
doing this already (I don't know the name of the company), taking regular
cable
modems and using wireless for intramodem communication (why re-invent the
wheel)
instead of copper.

That would be a good idea.

regards,
fletcher

2

> > The Ethernet protocol was designed to adjudicate and route packets
> > internal to one homogeneous, physical network. It handles media
> > access, security, reliablity and routing in that one physical network.
>
> What does Ethernet have to do with routing ?

Routing in its original sense. You stick an Ethernet frame in here,
it traverses a number wires connected by boxes which make decisions as
to which wire it should go out on. It then pops out on the other edge
of the network. Magic!

A network of Ethernet switches looks a heck of a lot like routers.
They are certainly smarter than the IP routers of circa 1983.

> The problem you dont really have one physical network. We are trying
> to extend Ethernet into a logical network.

Who is "we" in this statement?

Those using PPPoATM/E

> The
> reason that I like PPPoATM is that the end device requires littel
> intelligence , it knows one PVC, and all changes (linking them to the
> ISP of choice, propogate easily downstream)

Little intelligence to implement ATM? Never heard that claim before.

Much easier to place a $300 CPE (Cisco 678 which speaks ATM). Than a 1605
(chosen for the fact that its about the cheapest Dual Ethernet Router from
Cisco). How do you propose that we bring Ethernet to the customer ? The
now defunct CLEC that I worked for, used 678 and 1483 so that the 1605 did
the routing (as far as our netowork was concerened, we were
bridging/switching these customers, the fact that they ran IP was their
business).

Contrast the cost of an Ethernet chip with an ATM chipset.

ATM to the desktop never took off, whats wrong with Ethernet over ATM ?
With devices such as
IADS, it allows for easy differentiation of traffic. Now you can cary voice
and data over the same
physical link without worry. ATM is expensive in the core but inexpensive
at the customer prem ($300 for a ATM DSL modem is relativel cheap,
especially since it is a router , if you want it to be).

> .RFC 1483 (Ethernet over
> ATM, used in DSL and plausibly in cable ) is a great idea for business
> but not suitable for home users. Hardware that you speak of becomes
> just too expensive.

Define "great idea". Compare and contrast with all the failed DSL
providers which used ATM. Use one DSL/ATM provider who is making money as
an example. No excuses please.

Market GLUT and not technology failed here. I was able to completely
reprovision a customer in about two minutes in a PPPoATM network we ran.
PPPoATM allows for a easily managable resale strategy, if your sales staff
and wholesalers can't sell the service, thats not the fault of the
technology.

How do you reconcile the cost of the hardware being too expensive with
the statement above that ATM requires little intelligence?

> It appears as if someone has thought of this before Someone is

apparently

> doing this already (I don't know the name of the company), taking

regular

> cable
> modems and using wireless for intramodem communication (why re-invent

the

3

[..]

Ever tried it without that? I have done quite a bit of less than scientific
testing of VoIP over a QoS-less infrastructures. Small VoIP packets seem to
have little trouble squeezing thru and it works actually pretty well. That's
without ATM QoS crap on a broadband connection.

4

> ATM to the desktop never took off, whats wrong with Ethernet over ATM ?
> With devices such as
> IADS, it allows for easy differentiation of traffic. Now you can cary

voice

> and data over the same
> physical link without worry.
[..]

Ever tried it without that? I have done quite a bit of less than

scientific

testing of VoIP over a QoS-less infrastructures. Small VoIP packets seem

to

have little trouble squeezing thru and it works actually pretty well.

That's

without ATM QoS crap on a broadband connection.

I have to concede here. We were able to run the VOIP traffic using UBR, out
network
not being saturated, this may have helped, on a busy network, a lot of
problems could have
arrisen. What is nice, is that QOS is easy to enable in ATM. There are
many reasons that
ATM has not taken off, from a CLEC perspective, I believe it to be the
superior technology.
I would much rather have a 10 Mbps Ethernet feed from a company like Cogent
but those
links do not compare in pricing with DSL.

--
Christian Kuhtz <ck@arch.bellsouth.net> -wk, <ck@gnu.org> -hm
Sr. Architect, Engineering & Architecture, BellSouth.net, Atlanta, GA,

U.S.