Subject: 15.2.1, Creation & Sending of Reconfigure-init messages

From: "Bernie Volz (EUD)" <[email-masked]>
Date: Thu, 19 Jul 2001 14:39:28 -0500

I believe Section 15.2.1 of -19 needs some edits.

It says:

   The server unicasts the Reconfigure-init message to one client.  The
   server may unicast Reconfigure-init messages to more than one client
   concurrently; for example, to reliably reconfigure all known clients,
   the server will unicast a Reconfigure-init message to each client.

Can we specify this a bit more tightly. What does "server unicasts"
mean? Does that mean directly to the client?

Well, consider that the server may not be able to do this. Why?
1) If the server did not assign any addresses to the client (just gave
it configuration information), how does it know how to contact the
client directly? All it may have is the client's link local address
(and the relay's address if relayed).
2) If the server did assign addresses, it may be that those addresses
are not of sufficient scope for the server to use to reach the client
directly. Even if they are, which address should it use (this may be
less of an issue but what if the preferred lifetimes have all elapsed
and the client may have removed the address - or *MUST* a client retain
the address until the valid lifetime expires?).

Therefore, I would suggest that the text be revised to indicate HOW
the server unicasts.

I suggest the following text:

  The server unicasts to the client by using one of the following
  methods:
  1) If the client is on one of the server's interfaces, the clients
  link local address is used. (The client's link local address must
  have been saved from a previous communication from the client.)
  2) If the client has been assigned an address of sufficient scope
  for the server to use in communicating with it and that address
  is still preferred, this address MAY be used.
  3) Otherwise, the Reconfigure-Init should be unicast to a relay
  agent (as a Relay-reply) and that relay will unicast it to the
  client's link local address. (The client's link local address and
  the relay's address must have been saved from a previous communication
  from the client; or a suiteable relay agent's address is known by
  some mechanism by the server.)

BTW, there may be 4 (or more correctly, it should be 2.5) ... if the
client has unicast a packet directly to the server (because of the
Server Unicast Option, Section 18.10), the server could save that
address and use it. However, if the server did not assign this address,
it may have no information about the validity of that address and
therefore I did not include it.

> Bernie Volz
> Chief Technical Officer - DNS & DHCP Development Unit
> Ericsson, Inc.
> Tel: +1-508-875-3162
> Fax: +1-508-875-3018
> Mobile: +1-617-513-9060
> mailto:[email-masked]
> 
>

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From: Jim Bound <[email-masked]>
Date: Thu, 19 Jul 2001 21:29:25 -0400 (EDT)

I don't agree with number 3.  A server who never gave the client its
address or even talkd to it can send a reconfigure-init to it.  How it
knew the clients address is implementation defined.  This behavior is
important.

/jim