Subject: Re: [dhcwg] CGAs and DHCP

From: Iljitsch van Beijnum <[email-masked]>
Date: Fri, 27 Jun 2008 17:45:56 +0200

I found this message that I missed way back when... Just in case this  
is still relevant:

On 18 mrt 2008, at 17:49, Templin, Fred L wrote:

> I would now like to
> specify a means for delegating a fully-qualified *prefix*
> (i.e., a /128) that includes a CGA using RFC3633 DHCP prefix
> delegation.

In my opinion, this is not a suitable use of the prefix delegation  
mechanism. Delegating prefixes incurs significant overhead in routers,  
because they have to set up routing for these prefixes. So doing that  
on a per-host basis is the wrong approach.

At a slightly higher level:

It looks like many people want to do many things with DHCPv6 that  
don't really work or are very inconvenient. Perhaps it's a better idea  
to collect these intended uses in a requirements document and then see  
what reasonable changes can be made to DHCPv6 to accommodate these uses.
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---

From: Frank Xia <[email-masked]>
Date: Fri, 27 Jun 2008 11:24:27 -0500

Hi folks

Please check my inline reply...

BR
Frank

----- Original Message ----- 
From: "Iljitsch van Beijnum" <[email-masked]>
To: "Templin, Fred L" <[email-masked]>
Cc: <[email-masked]>; <[email-masked]>; <[email-masked]>
Sent: Friday, June 27, 2008 10:45 AM
Subject: Re: CGAs and DHCP

> on a per-host basis is the wrong approach.
Frank=>In some senarios (e.g point-to-point link model), each host
is supposed to have a unique prefix. There are two ways to allocate
the prefixes, through router local prefix pool or through external
DHCP server.

As to routing overhead  if the prefixes is from 
an external DHCP server,  it is avoided by using aggregate routing 
method.  That is, the router only propagands it's aggregate
prefix information(e.g  /48 ) upstream, and not individual host prefix
information(e.g /64).   This is the similar solution used in DHCP IPv4
address allocation.

RFC3633 says "
   Note that this use of DHCP is not bound to the assignment of IP
   addresses or other configuration information to hosts, and that no
   mechanism is currently available to communicate delegated prefixes to
   a DHCP server that serves such a function.  This may be an item of
   future work, should usage warrant."

IMHO, it is time to deal with the solution.

> what reasonable changes can be made to DHCPv6 to accommodate these uses.
Frank=>Good idea. I would like to join.