Subject: Advertising prefixes

From: Ralph Droms <[email-masked]>
Date: Wed, 07 Feb 2001 08:43:55 -0500

Prior to the -16 rev of the DHCPv6 draft, we decided to limit DHCPv6 to the 
assignment of addresses and eliminated the advertisement of 
prefixes.  After thinking about some address management scenarios, it seems 
to me that it might be useful to combine DHCP and stateless 
autoconfiguration to provide host-specific prefix configuration without 
individual address management.

My proposal is to allow a DHCP server to assign prefixes as well as 
addresses in an IA to a client.  For example, the prefix might be carried 
in an IA as an address with all 0s in the low order bits (those bits not 
included in the prefix).  The client would then apply stateless autoconfig 
to those DHCP-assigned prefixes.  The client might also use the 
DHCP-assigned prefixes to generate anonymous addresses.

DHCP assignment of prefixes would be useful in "managed access" networks, 
where not all of the prefixes assigned to a link are to be used by every 
client on that link.

- Ralph

---

From: "Bernie Volz (EUD)" <[email-masked]>
Date: Mon, 19 Feb 2001 13:21:06 -0600

Ralph:

I don't suppose there is any easy way to defer this for later consideration - be nice to focus on the core functionality now. Perhaps one solution is to send these prefix advertisements in a new option (not use the Identity association option). Though there likely would be some backwards compatibility issues.

One other thought is why not just have the server do this work (ie, assign the address rather than advertise the prefix) rather than having the client (and client's IPv6 stack) handle yet one more thing and one more type of address.

Finally, if you use the Identity association option, what implication does the lease time have on these prefix advertisements? What if all the Identity association option contained was prefix advertisements (no addresses)?

- Bernie Volz
  Ericsson

-----Original Message-----
From: Ralph Droms [mailto:[email-masked]]
Sent: Wednesday, February 07, 2001 8:44 AM
To: DHCPv6 discussion list
Subject: Advertising prefixes

- Ralph