v6 subnet size for DSL & leased line customers

Christopher Morrow morrowc.lists at gmail.com
Thu Dec 27 19:26:34 UTC 2007

On Dec 27, 2007 5:27 AM, Iljitsch van Beijnum <iljitsch at muada.com> wrote:

> With IPv4, a lot of these features are developed by vendors and
> (sometimes) later standardized in the IETF or elsewhere. With IPv6,
> the vendors haven't quite caught up with the IETF standardization
> efforts yet, so the situation is samewhat different. For instance,
> SEND/CGA is excellent work, but we've only recently seen the first
> implementations.

first implementations, in a protocol that's 'fully baked' (according
to ietf closing down the v6 WG) and been in 'production' for 15 years?
for features that have existed in the v4 network for 5+ years? ouch...
 This gets back to my point about having feature parity and the fact
that that is important. People have deployed rather large environments
that require these features, not having them is a step backwards and
painful for the operators in question.

> What this all boils down to is that if you want to deploy DHCPv6 you
> need to install software on a lot of systems and modify a lot of

'the largest deployed platform' already has this built-in, yes? (vista/xp)

> configurations. If you're going to do all that, it's easier to simply
> configure this stuff manually. The only downside to that is that it's

you are crazy... seriously, have you walked around to 10k or 50k
machines or attempted to get helpdesky people to do the same? have you
considered that this all works fine in v4, is tied into my OSS
backends and is a part of my business process? Getting some new
software (firefox is a fine example) deployed to 50k workstations is
an overnight event... SMS (or whatever the new MS equivalent is) rolls
out the software update, there are many other options (tivoli,
ca-unicenter, custom-foo) which will also do this work for you,
getting proper and dynamic setup of IP info (my earlier example of
resolvers) isn't quite as simple unless you use dhcp.

> not compatible with easy renumbering, but then, you need to do more
> than just automate address assignment to support easy renumbering.

sure, like deploy v6... wait, that doesn't do it either :( It's not
just renumbering, it's migration of services which the network
elements are reliant on (dns, wins, tftp-root/nfs-root...) tieing my
laptop to the same addr each time for some process including logs and
HR details and SoX compliance perhaps. This is a bighairy beast, just
saying 'dhcpv6 isnt possible use autoconf' is never going to be

> That being said, please go to your vendors and tell them what you
> need. Preferably at a high level, so they can provide the
> functionality in the optimal way, rather than just revert back to the
> IPv4 way of doing things.

also be sure to let your standards body(s) know that some form of
feature parity is relevant. I think often there is a missing message
between operators and the other folks :( this clearly (to me atleast)
seems like one of those areas.


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