Re: [dhcwg] Comments on 22 rev of the draft

Ted Lemon <> Wed, 23 January 2002 20:42 UTC

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Date: Wed, 23 Jan 2002 21:17:51 +0100
Subject: Re: [dhcwg] Comments on 22 rev of the draft
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To: Vijay Bhaskar A K <>
From: Ted Lemon <>
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> Router is advertising  3ffe::/64
> prefix and a host has generated an address of prefix  3ffe::/64  using
> router  advertisements.  Now, the host  needs  some  more  addresses  of
> prefix  3ffe::/64.

Why would the client want to do this?   What mechanism would cause the 
client to do this?

> It chooses to use stateful  autoconf  (dhcpv6).  The
> server  sends  advertise  saying  that,  it can  allocate  addresses  in
> 3ffe::/64  and  5ffe::/64.

Unless I misunderstand the DHCPv6 draft, this is _not_ how it works.   The 
server allocates addresses for the client.   The client can ask for 
temporary addresses, but otherwise it simply takes what the server offers.
    There's no either-or proposition here - the server offers what it offers,
  and the client takes all of it.   There is no reason why the client should 
need to pick and choose - if the server says it will give the client 
addresses on both these networks in the DHCP Advertise message, then when 
the client sends a DHCP Request message, the DHCP server will in fact give 
the client addresses on both these networks.   AFAIK it is not intended in 
the draft that the client either need to nor be able to pick and choose 
among addresses within an IA.

> Obviosuly, the client using the stateless  autoconf,  knows the prefixes
> in the link, (by router advertisements).  From the Advertise messages of
> the various servers, it knows about the prefixes in the link.

This is not only not true, but it doesn't answer the question I asked.   
Unless I am dreadfully mistaken, there is no requirement that there be a 
router on a link in order for IPv6 networking to function.   And the 
question was not "how does the client know what prefixes are available on 
the link," but rather, "on what basis would the client want to choose 
between such prefixes?"

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