Subject: A6 and DNAME

From: "Bernie Volz (EUD)" <[email-masked]>
Date: Mon, 30 Apr 2001 15:58:08 -0500

Hi:

One more item to add to the recent discussion (which I've only partially followed) on A6 and DNAME records is ... how are they created and used in the first place?

If one assumes that IPv6 addresses are automatically generated (either using autoconfiguration or DHCPv6), then how does an A6 record with non-0 prefix length ever get added in the first place? There hasn't been any method developed (that I'm aware of) to communicate to a client or DHCPv6 server that it should register these addresses under a given prefix. Also, if it were to do this, what happens if the prefix is multi-homed yet the address allocated to the client isn't (only one of the prefixes is in use)? This would significantly complicate clients and DHCPv6 servers since they may have to pull together several addresses before being able to register under the non-0 prefix? And the failure modes (such as not getting one address because of DAD or other reasons) are difficult to deal with.

Same happens with the PTR records and DNAME ... how is the client or DHCPv6 server told to use a particular DNAME to register?

Seems to me that most clients and DHCPv6 servers will register with the full 128-bits and therefore this fancy stuff won't be used anyway - since nothing will be in place to set it up.

Sure, we could add a DHCPv6 option to communicate these details. But, what about when DHCPv6 isn't used and autoconfiguration is used?

Sorry if this has already been raised as an issue and I missed it.

- Bernie Volz