Re: [dhcwg] Follow up on WGLC Comment on draft-ietf-dhc-rfc3315bis-05 - numbering the uplink

["Bernie Volz (volz)" <[e-mail]>]

Tim:

draft-ietf-v6ops-unique-ipv6-prefix-per-host-01 says nothing about using IA_PDs  / DHCPv6 prefix delegation … so not sure it is appropriate to reference it in this context.

The text in draft-ietf-dhc-rfc3315bis-06 section 18.2.10.1 is:

   -  For each delegated prefix, the client assigns a subnet to each of
      the links to which the associated interfaces are attached, with
      the following exception: the client MUST NOT assign any delegated
      prefixes or subnets from the delegated prefix(es) to the link
      through which it received the DHCP message from the server (see
      [RFC6603<https://tools.ietf.org/html/rfc6603>] for exceptions).

RFC 6603 is the prefix-exclude option which allows for a subnet from the delegated prefix to be used.

I wonder if we could change the text above to read:

   -  For each delegated prefix, the client assigns a subnet to each of
      the links to which the associated interfaces are attached, with
      the following exception: the client MUST NOT advertise any delegated
      prefixes or subnets from the delegated prefix(es) to the link
      through which it received the DHCP message from the server (see
      [RFC6603<https://tools.ietf.org/html/rfc6603>] for exceptions).

The change here is “assign” to “advertise” (as in send a router advertise with a PIO on that link). This would allow the client to “assign” the subnet to that link, but just not advertise it on that link.

If you want to suggest better and more clear wording than just that single word change or that wasn’t the intention, please do!


-          Bernie

From: Tim Chown [mailto:[e-mail]]
Sent: Thursday, December 08, 2016 8:42 AM
To: Bernie Volz (volz) <[e-mail]>
Cc: Lorenzo Colitti <[e-mail]>; [e-mail]
Subject: Re: Follow up on WGLC Comment on draft-ietf-dhc-rfc3315bis-05 - numbering the uplink

On 7 Dec 2016, at 14:37, Bernie Volz (volz) <[e-mail]<mailto:[e-mail]>> wrote:

In https://www.ietf.org/mail-archive/web/dhcwg/current/msg17590.html, Tim commented:

Section 17.1.10.1 (-05, this is 18.2.10.1 in the -06 document):
p.60 [p. 58] There was discussion in 6man/v6ops about using a /64 from the delegated prefix for a site for numbering the uplink. I think Jordi’s recent survey of ISPs showed this was more common than expected? So do we want to say MUST NOT assign here?  (I have no strong feeling myself…)

A question for Tim and Lorenzo (and others) is should we do something to relax this “MUST NOT” given the interest in using PD to clients (not just routers).

To be specific, the /64-to-the-host context is as per draft-ietf-v6ops-unique-ipv6-prefix-per-host-01.


I think a key point here is not to assign the uplink (delegating) router an address from the delegated prefix on that downlink interface? But that shouldn’t prevent the client itself from assigning an address on that interface from the delegated prefix.

Indeed, and the above draft describes the process for the host using a /128 from the delegated prefix, and use of DAD, at the end of section 4.

Tim