Re: [dhcwg] dhcwg Digest, DHCP Renew vs Confirm

Hi Bernie,
	I asked Ole about this at V6 World Congress last week, and he mentioned that it wasn't in RFC 3633 because Confirm is for detecting on-link confirmation.   It's possible I misunderstood him, if so he can feel free to jump in.

	As you point out RFC 3315 doesn't prevent an implementation from transmitting a Renew message when this happens.   So they are within the specification for transmitting the Renew message.  The missing piece is that we have DHCP clients, in this case CE Routers, that don't transmit Confirm messages. RFC 3315 states a Confirm message should happen when a device may have moved to another link, so unplugging the physical link should cause a DHCP Confirm message when plugged back in.  

	Is a DHCP Client not following RFC 3315 if they don't transmit a DHCP Confirm message? 

Regards,
Tim

On Feb 15, 2012, at 10:29 PM, Bernie Volz (volz) wrote:

> I don’t really see what’s wrong with EITHER a REBIND or CONFIRM (or even both, one for IA_PD and one for address). Not really sure why RFC 3633 didn’t permit a Confirm.
>  
> However, if one does a strict read of the standards, the two (Confirm for address, Renew for PD) is what a  client SHOULD do.
>  
> But, there’s no reason a prefix can’t be confirmed just as easily as an address.
>  
> Perhaps Ole had a reason for this in RFC 3633, but alas it is not documented (at least that I could see).
>  
> And, a Rebind (for an address) at any time isn’t really “wrong”.
>  
> For a compliance test, you are probably forced to follow the standards as that is the only thing that you can assure (a server may be strict in following RFC 3633 and consider a Confirm with prefixes “wrong”). (Cisco Network Registrar will deal with all of the possibilities.)
> -          Bernie
>  
> From: dhcwg-bounces@ietf.org [mailto:dhcwg-bounces@ietf.org] On Behalf Of Huan Huan
> Sent: Wednesday, February 15, 2012 8:56 PM
> To: Timothy Winters
> Cc: dhcwg@ietf.org
> Subject: Re: [dhcwg] dhcwg Digest, DHCP Renew vs Confirm
>  
> I don't think so.
>  
> 2012/2/15 Timothy Winters <twinters@iol.unh.edu>
> Hi Huan,
>       Is it ok to transmit just a Renew message containing both the IA_NA and IA_PD when the link goes down?
>  
> Regards,
> Tim
> 
> 
> On Feb 14, 2012, at 8:12 PM, Huan Huan <shawngespan@gmail.com> wrote:
> 
> Hi Tim,
>  
> I think CE Router may transmit Confirm msg containing the assigned IA_NA and Renew msg containing the assigned IA_PD separately.
>  
> BR,
> Huan 
> 
> 2012/2/15 <dhcwg-request@ietf.org>
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> Today's Topics:
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>   1. I-D Action: draft-ietf-dhc-forcerenew-nonce-04.txt
>      (internet-drafts@ietf.org)
>   2. DHCP Renew vs Confirm (Timothy Winters)
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Tue, 14 Feb 2012 02:40:41 -0800
> From: internet-drafts@ietf.org
> To: i-d-announce@ietf.org
> Cc: dhcwg@ietf.org
> Subject: [dhcwg] I-D Action: draft-ietf-dhc-forcerenew-nonce-04.txt
> Message-ID: <20120214104041.23040.30559.idtracker@ietfa.amsl.com>
> Content-Type: text/plain; charset="utf-8"
> 
> 
> A New Internet-Draft is available from the on-line Internet-Drafts directories. This draft is a work item of the Dynamic Host Configuration Working Group of the IETF.
> 
>        Title           : Forcerenew Nonce Authentication
>        Author(s)       : David Miles
>                          Wojciech Dec
>                          James Bristow
>                          Roberta Maglione
>        Filename        : draft-ietf-dhc-forcerenew-nonce-04.txt
>        Pages           : 12
>        Date            : 2012-02-14
> 
>   Dynamic Host Configuration Protocol (DHCP) FORCERENEW allows for the
>   reconfiguration of a single host by forcing the DHCP client into a
>   Renew state on a trigger from the DHCP server.  In Forcerenew Nonce
>   Authentication the server sends a nonce to the client on the initial
>   DHCP ACK that is used for subsequent validation of a FORCERENEW
>   message.  This document updates RFC 3203.
> 
> 
> A URL for this Internet-Draft is:
> http://www.ietf.org/internet-drafts/draft-ietf-dhc-forcerenew-nonce-04.txt
> 
> Internet-Drafts are also available by anonymous FTP at:
> ftp://ftp.ietf.org/internet-drafts/
> 
> This Internet-Draft can be retrieved at:
> ftp://ftp.ietf.org/internet-drafts/draft-ietf-dhc-forcerenew-nonce-04.txt
> 
> 
> 
> ------------------------------
> 
> Message: 2
> Date: Tue, 14 Feb 2012 08:43:50 -0500
> From: Timothy Winters <twinters@iol.unh.edu>
> To: dhcwg@ietf.org
> Subject: [dhcwg] DHCP Renew vs Confirm
> Message-ID: <C0CA95B6-1743-4D37-9BCC-D104453EBF9A@iol.unh.edu>
> Content-Type: text/plain; charset=us-ascii
> 
> Hello,
>        While testing some CE Router implementations we have noticed a interesting behavior that is within the specifications but not clearly documented.  I wanted to get the working group thoughts on this.
> 
>        Currently when a CE Router acting as a DHCP client, assigned both IA_NA and IA_PD, is unplugged from the network.  When reattached to the link the DHCP client transmits a DHCP Renew containing both the IA_NA and the IA_PD.
> 
>        3315 Section 18.1.2 says that when link goes down a DHCP client implementation should transmit a DHCP Confirm message containing the assigned IA_NA.
> 
>        3633 Section 12.1 doesn't allow the use of the Confirm message.  It states that DHCP Renew message, containing the assigned IA_PD, should be used when the link goes down.
> 
>        According to the specifications a DHCP client should retransmit DHCP Confirm and DHCP Renew when link goes up.   The behavior we are seeing is the DHCP client transmits a DHCP renew containing both the IA_NA and IA_PD.
> 
>        This behavior isn't causing interoperability issues as all the servers we have tried still respond properly to the DHCP Renew messages.
> 
>        Is it ok when a DHCP client loses link for it to transmit one DHCP Renew message?
> 
> Regards,
> Tim
> UNH-IOL
> 
> 
> 
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> End of dhcwg Digest, Vol 94, Issue 13
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> 
>  
> -- 
> Huan Huan
> 
> 
>  
> -- 
> Huan Huan