Subject: RE: Design team teleconference, 8/31

From: Bernie Volz <[email-masked]>
Date: Thu, 14 Sep 2000 15:52:55 -0400

While I agree with Ralph's reasoning for using the DHCPv4 messages, I do
believe that we should use different names because:
- The message formats are no where near close
- The behavior of the protocol (and what the messages cause to occur and
communicate) is different in significant ways

I think it will REDUCE confusion in the long run to use different names
because we'll know instantly what we're taking about when we say SOLICIT
message. If use DISCOVER for both V4 and V6, we'll constantly have to say
"v4 DISCOVER or v6 DISCOVER".

So in summary, I think they are different enough to warrant different names.

- Bernie

-----Original Message-----
From: Ralph Droms [mailto:[email-masked]]
Sent: Thursday, September 14, 2000 3:33 PM
To: DHCPv6 discussion list
Subject: Re: Design team teleconference, 8/31

At 11:39 PM 9/7/00 -0400, you wrote:
>Was not clear what thread to post this too.  But one of the discussions
>was the name of the messages.

Right - I'm not sure we actually got that thread kicked off.  It was my 
question - do we need different semantics and message names for DHCPv6 or 
can we reuse the technology from DHCPv4?

For example, the DHCPv6 Solicit message now acts pretty much like the 
DHCPv4 DHCPDISCOVER message (allowing for differences in the message 
formats).  The Advertise message acts pretty much like a DHCPOFFER, except 
the Advertise doesn't include any offered parameters.  is there a reason 
for the difference or could we include parameters in the DHCPv6 message and 
call it a DHCPOFFER?

>   The current DHCPv6 message names
>correspond directly to Neighbor Discovery rfc 2462 thats where they came
>from.  I think it more important to stay in synch with that part of IPv6
>than DHCPv4.

If the messages are really different messages - with different semantics - 
then sure, we should go with RFC 2462.  If the DHCPv6 messages walk and 
quack like DISCOVER/OFFER/REQUEST/ACK then that's what we oughta call 'em...

- Ralph

---

From: "Ralph E. Droms" <[email-masked]>
Date: Thu, 14 Sep 2000 16:55:55 -0400 (EDT)

> - The message formats are no where near close

I claim the message formats aren't important in this context.  A
pretty-printer can make them look the same when snooping packets...

> communicate) is different in significant ways

I don't believe that we've shown that the messages *must* have different
semantics.  I gave two examples of how Solicit/DHCPDISCOVER and
Advertise/DHCPOFFER have come to have quite similar semantics.  I'd like
to see a convincing argument that the remaining differences are important
to the operation of DHCPng.

- Ralph

---

From: Ted Lemon <[email-masked]>
Date: Thu, 14 Sep 2000 14:24:25 -0700

> I'd like to see a convincing argument that the remaining differences
> are important to the operation of DHCPng.

I don't think they are.   I don't mind the new semantics, and I think
they make sense, but the old semantics make sense too.   I think that
with the additional addressing complexity of DHCPng, the old semantics
probably aren't as useful, but that doesn't mean we *have* to get rid
of them.

			       _MelloN_

---

From: Jim Bound <[email-masked]>
Date: Fri, 15 Sep 2000 00:53:56 -0400

Ralph,

>pretty-printer can make them look the same when snooping packets...

Bernie and I said the messages are not even close in context?

Why is that not convincing?  

>> communicate) is different in significant ways

I think I did and so did Bernie?  Can you respond to that part of the
mail too so I can understand why you don't think it applies.

>to the operation of DHCPng.

I don't believe you or anyone has shown a compelling reason to change
the existing names.   Maybe I missed it in the mail.  
I have countered and so has Bernie your statements above that the
semantics are different and also affect the servers differently?

I think we are at a crossroad.  I believe we have show cases wher e the
messages are not the same at all.  

In fact I think solicit is more appropriate than the word discover.

They have been in the specs as words for a long time.  I don't think
you have shown a compelling strategic or technical reason to change
them?  

regards,
/jim

- Ralph

---

From: Jim Bound <[email-masked]>
Date: Fri, 15 Sep 2000 01:09:01 -0400

>probably aren't as useful, but that doesn't mean we *have* to get rid

The design minutes state DHCPng is for the future.  But we want to try
to not do anything that will prohibit a ***future*** DHCPng.  But what
my impression is that what we are working on here is DHCPv6.

I see no reason why the existing message names are not appropriate. The
existing messages do different functions than DHCPv4 but can support
DHCPv4.  I claim the reverse is not true for DHCPv4 messages and have
sent other mail why syntactically the existing messages are better and
open to hearing why I am wrong and on the other mail.

In fact I think we have this backwards.  Proponents of changing the
message names should be defending their change not the current names.

regards,
/jim

---

From: Ted Lemon <[email-masked]>
Date: Thu, 14 Sep 2000 22:40:57 -0700

The advantage of DHCPDISCOVER/DHCPOFFER is that the DHCPDISCOVER
message asks for an IP address, and DHCPOFFER can say "this is the
address I will give you if you pick me."  DHCPsolicit/DHCPadvertise
doesn't provide this functionality.  I think that this is useful
functionality, and I am loath to give it up.

I can see why you like your new way of doing things, but there is
definitely a good reason to continue with the old method, or at least
so it seems to me.  Is this a strong enough reason to go back?   I
can't say.   In my mind it is.   It sounds like Ralph agrees.   I'd be
interested in seeing if anybody else wants to weigh in on the issue.

			       _MelloN_

---

From: Jim Bound <[email-masked]>
Date: Fri, 15 Sep 2000 02:41:45 -0400

>functionality, and I am loath to give it up.

Not quite.  Advertise permits one to give the client addresses too with
extensions.

But presently we also require that a request must then be done.

>interested in seeing if anybody else wants to weigh in on the issue.

Not my new way.  I had initially solicit and request and reply really
simple stuff.  THe model today currently was the WGs the past 3 years.
Not mine.  I think we need a fast commit esp for mobile nodes.  I think
the advertise can support that.  But thats another thread.

I agree need others to weigh in.  Also its not just me its Bernie and
me on keeping existing names.

Others???

regards,
/jim