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Re: Cable Modem [really more about PPPoE]

  • From: Chris White
  • Date: Tue Jun 26 12:29:29 2001

On Tue, 26 Jun 2001, William Allen Simpson wrote:

> Chris White wrote:
> > 
> > DHCP alone is not a viable option in this model. How do you get the end
> > user traffic to the ISP and back in a pure IP environment? 
> Very easily.  The ISP has a NAS at the headend (or even in every 
> block).  The cablemodem is a router that talks to the NAS, just as in 
> any other environment.  The NAS performs DHCP, just as in any other 
> environment.  The carrier provides commodity service, just as in any 
> other environment. ;-)

The cable modem may be a router. A large number of DSL modems are not.
Most (if not all) 802.11b wireless endpoints are not (these are very
common in large scale deployments at the moment - long term viability is
another issue) 

> For access control, you need IPsec.  But you need IPsec for security 
> and privacy anyway on a broadcast medium.  This is really no different 
> than wireless.

Agreed, but this is an additional client software on most end user systems 
unless you have an IPsec capable router and it adds a substantial cost at
the termination point if you were to use IPsec tunnels to hand off the
customers to another provider. 

> (Hint, we discussed this stuff in the IP/cable working group many years 
> ago....  And I specified Mobile-IP to handle moving seamlessly between 
> cellular and broadband networks back in '92-93.  Should stop rehashing 
> very old arguments.)

I looked into Mobile-IP for a wireless deployment...requires a client and
is not well supported at this time. Someday maybe...

> > In a wireless environment this becomes even more of a consideration as
> > most of the current hardware is limited in ATM or L3 functionality...
> > 
> I shudder to think of trying to deploy ATM over wireless.
> I don't know why you would deploy at L3, it seems rather far away -- 
> but if you perhaps mean IP, then I don't expect wireless that isn't 
> IP capable, going back to Tetherless Access Limited, and before that to 
> amateur radio.  Nobody would use it otherwise!

I was talking about the functionality of the client stations. Most are no
more than bridges at this time.

> William Allen Simpson
>     Key fingerprint =  17 40 5E 67 15 6F 31 26  DD 0D B9 9B 6A 15 2C 32

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