Subject: Issue from San Diego IETF - temporary addresses

From: "Bernie Volz (EUD)" <[email-masked]>
Date: Mon, 19 Feb 2001 15:08:48 -0600

>From the San Diego IETF minutes:

* Narten also raised issue of interaction between DHCP and temporary addresses. DHCP server can provide temporary addresses by assigning addresses with short lifetimes. However, there will be an API through which an application can request a temporary address. How can the DHCP server indicate to the client which addresses are to be "temporary" and which are "permanent"? Narten thinks IESG will bounce anything that doesn't deal with temporary addresses. He will develop requirements doc so WG can develop solution. 

Shouldn't this say "How can the DHCP client indicate to the server which addreses are to be "temporary" and which are "permanent"? It is after all the client that might have an understanding of how long the address is desired.

As the client will send an "Identity Association Option" to request address(es), couldn't this simply be communicated via a lease request time? Though there probably is no good field to store this in.

And, then we should perhaps ask WHY DOES THE SERVER CARE? If the client wants a short lease, the server simply grants it the address(es) for however long the server policy dictates. If the client doesn't want to use the address after a period of time, it is ALWAYS able to RELEASE it whenever it is done. Even if it doesn't release it but instead simply lets it expire, what's the harm? There should be plenty of addresses available in IPv6.

Of course, the requirements document might help answer why Thomas feels there is a need to have a mechanism to explicitly request these temporary addresses. Perhaps the reason for the 'temporary' addresses is that they are supposed to be 'random' instead of based on the EUI-64 identifier of the client; but as a previous message pointed out nothing has been said as to how a DHCP server will assign addresses.

A question ... should the "Identity Association Option" that the client sends the server be identical to the one that the server sends the client? Or, might it be better to have two options - one which is sent by the client and another that is sent by the server? The one sent by the server is what's specified in the -16 draft. A different one might be specified for the cleint to send (such as without T1, T2, and lifetimes, etc). Perhaps this would also make it easier to add in a field for the client to request the length of the desired lease time.

- Bernie Volz
  Ericsson