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Re: Cable Modem [really more about PPPoE]

  • From: Daniel Senie
  • Date: Tue Jun 26 12:44:06 2001 
At 12:21 PM 6/26/01, Steve Schaefer wrote:
On Tue, 26 Jun 2001, Fletcher E Kittredge wrote:

>
> On Tue, 26 Jun 2001 10:28:16 -0400 (EDT) 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? Policy routing,
> > GRE, MPLS, force your ISP customer to interconnect at every location,
> > etc.?
>
> Hello Chris;
>
> You provide frustrating few details and a statement "DHCP alone is not
> a viable option in this model." Could you restate more concretely
> what is your design problem which can only be solved by
> ATM/MPLS/PPPoE? I hesitate to answer for fear that there is some
> constraint I don't know about.

The constraint is that outbound packets need to go to the right ISP. That
is, the packets need to go through the carrier network according to the
business relationship, not according to the destination IP address.
This isn't necessarily the case. Take a look at rent-a-POP dialups. UUNet sells services to LOTS of ISPs from all of its POPs. The RADIUS authentication has to get to the proper ISP, but the traffic certainly does NOT travel to the ISP's network before going out into the world. Traceroutes from your dialup account will show that the traffic goes directly. UUNet charges the ISP a fee for the use of the dialup, and UUNet provides a relaying of the RADIUS traffic to the right ISP, and provides transport for the end user's packets.

The same scenario COULD be used in DSL or cable setups. That's not to say that it will be.


Some method of identifying the ISP associated with each outbound packet is
necessary.  Policy routing, tunnels and PVC's are a few methods.  VLAN
tagging works, too.

Right. Assuming the business model where the ISP actually handles the traffic.
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Daniel Senie                                        [email protected]
Amaranth Networks Inc.                    http://www.amaranth.com