RE: draft-wbeebee-ipv6-cpe-router-04 comments

["Wes Beebee (wbeebee)" <wbeebee@cisco.com>]

A cable modem can have an embedded CPE Router - known as an eRouter in
CableLabs parlance.  If the user desires wireless (802.11) connectivity
in their home, they may also buy a Wireless Access Point, which also is
typically a CPE router, and connect the two together.   This is a very
simple, and common, expected deployment (millions of people may have
this in the future), which requires cascading of CPE Routers.

- Wes 

-----Original Message-----
From: owner-v6ops@ops.ietf.org [mailto:owner-v6ops@ops.ietf.org] On
Behalf Of Antonio Querubin
Sent: Friday, March 27, 2009 5:02 PM
To: Stark, Barbara
Cc: swmike@swm.pp.se; v6ops@ops.ietf.org
Subject: Re: draft-wbeebee-ipv6-cpe-router-04 comments

On Thu, 26 Mar 2009, Stark, Barbara wrote:

> That's an interesting use case, with definite application, but I 
> wonder if it's really compelling in the case of the simple CPE Router.
>
> When CPE Routers are cascaded, the cascaded router is generally 
> directly connected to the upstream router, so that there would be no 
> added efficiencies from this.

I don't think it's that uncommon.  I've seen households, small
businesses, churches, etc that have multiple routers/switches/WAP
devices scattered throughout the home or their buildings/offices.  While
these types of deployments do not represent a very large percentage of
how these devices are being used, I think we'll see more and more of
these devices being cascaded together just for the addition of ports or
access points.  The cost difference between a switch-only device vs a
router is so minimal that many consumers opt for the latter even though
all they really need is another switch in most cases.  Few of these
entities have IT staff to advise them otherwise, nevermind efficiency.
Last time I browsed the network section of a computer store, I saw as
many wireless devices with built-in routers vs just standalone
WAPs/switches.  Same for the firewall/NAT devices.

Changing the topic slightly, it seems to me that one of the big
challenges for the CPER is determining how the prefix sub-delegation
behaviour should be when you do have cascaded devices.  Current IPv4
devices just avoid the issue by doing NAT upon NAT.  If IPv6 frees users
from limits on addresses and subnets then the CPER behaviour should be
designed to automatically handle the partitioning of the SP-delegated
/56 or /48 among 2 or more downstream CPERs.  Should we try to spell out
a recommended behaviour in more detail or are we gonna leave that up to
vendor implementation?

Antonio Querubin
whois:  AQ7-ARIN