Re: [dhcwg] Brokenness of specs w.r.t. client behavior with M&O bits

[Ralph Droms <[e-mail]>]

Greg - RFC 3736 is simply a summary of how DHCPv6 can be used with a  
two-message exchange and a simplified server.  It was intended to  
describe how DHCPv6 might be implemented in network elements to  
provide "other configuration information" without the "overhead" of a  
full-featured DHCPv6 server.  RFC 3736 does *not* describe the only  
way in which a client can get "other configuration information" from a  
server.

If I were doing a client implementation, I would be tempted to key the  
use of DHCPv6 from the availability of addresses and other  
configuration information.  That is, I would guess it would be  
unlikely that a client would use DHCPv6 for address assignment if the  
client has a manually assigned address or a SLAAC address, and I would  
guess the client would use DHCPv6 for other configuration information  
if it doesn't have manually configured information like DNS servers,  
etc.  I would likely set up the DHCPv6 client to send a Solicit if it  
has no other addresses (RA doesn't have 'A' set in prefix advert, no  
manual address) and send an Information-request if it does have  
assigned addresses.

Arguably, this analysis over-simplifies - suppose the host is attached  
to a multi-homed network that uses SLAAC for addresses from one  
upstream network and DHCP for addresses from another.  In that case, I  
suppose the host would have to use both SLAAC and DHCPv6 ... which, I  
suppose, would be OK if the host got the SLAAC prefixes from one  
router and the DHCPv6 prefixes from another.

- Ralph

On Oct 13, 2008, at Oct 13, 2008,5:15 PM, <[e-mail]> wrote:

>> A DHCPv6 server will answer all Solicits, even if it has no  
>> addresses to provide, with an Advertise.  The difference is in the  
>> status code in each IA.
>
> I don't believe that is an accurate statement.  According to RFC  
> 3736 section 5.1, clients and servers implement the following  
> messages for stateless DHCP service:  Info-Request, Reply, Relay- 
> Forward, and Relay-Reply.
>
> So, there is no Solicit and no Advertise with Stateless DHCPv6.
>
> Greg
>
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