Cable Modem [really more about PPPoE]

Tue Jun 26 14:28:16 UTC 2001

Let me start out by saying I am not a proponent of client software
and personally avoid using it if possible. In some cases it is a
consideration though.

Consider the following.

You have a large (Regional/National) cable/wireless/DSL deployment and
resell the last mile to ISP customers. 

There are two potential business models for this network. (according to
your marketing department)

One would be to partner with your ISP customers where
they resell your services targeting the residential market. DHCP will work
fine in this configuration where you provide the internet transit and
maintain
control over the customer.

The other would be to Wholesale the last mile connection to the ISP
customer. In this scenario you need to hand off the end user traffic to
your ISP customers.
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? Policy routing,
GRE, MPLS, force your ISP customer to interconnect at every location,
etc.?

At this point ATM and PPPoE become considerations each with its own 
advantages. If the service offering is business class ATM may be preferred
(required by your customer) for COS/QOS. From a configuration management
standpoint PPPoE has advantages especially in a residential environment as
you do not need to reconfigure the PVC when the end user changes
providors.

In a wireless environment this becomes even more of a consideration as
most of the current hardware is limited in ATM or L3 functionality...

Most network designs/business models are more complex than this but I did
not feel like typing that much:)

I do not intend to argue one technology over another, just to point out
that there are reasons PPPoE exists and is in use.....

A good network design also needs to consider the business model of the
company it supports.