Subject: RE: M & O Bits was: draft-ietf-ipv6-node-requirements-01.txt

From: [email-masked]
Date: Thu, 6 Feb 2003 14:39:19 +0200

Hi Brian(s);

> > My concern is the scenario where an operator knowingly disables
> > prefix advertisements and enables DHCPv6.  If the nodes doesn't
> > do DHCP, it is stuck with only the link-local address.
> 
> Understood. That certainly deserves a health warning. But in large
> scale deployments of low-end devices, implementors need to feel
> free to leave DHCP out. 

Just a small comment - 2462 (stateless aa) is a MUST.  Additionally,
manual configuration is always a possibility as well.  If certain
hosts know they don't need DHCP, then I don't see the problem of
having DHCP as a MAY. 

In general, stateless address autoconfig is a good thing, so we want
to encourage service providers to do the right thing.

br,
John

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From: Jari Arkko <[email-masked]>
Date: Thu, 06 Feb 2003 15:14:57 +0200

> to encourage service providers to do the right thing.

Maybe the right thing is to attach a warning or an explanation
about the implications and leave the support as a MAY. For
instance,

   "Nodes that do not implement DHCP may become unable to
    communicate outside the link when their routers advertise
    stateful autoconfiguration and no prefixes suitable
    for stateless autoconfiguration are offered."

Jari

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From: Brian Haberman <[email-masked]>
Date: Thu, 06 Feb 2003 08:37:45 -0500

>    for stateless autoconfiguration are offered."

If that type of text is in the doc, I will support a MAY.

Brian

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From: Ralph Droms <[email-masked]>
Date: Thu, 06 Feb 2003 08:48:54 -0500

Jari,

At 03:14 PM 2/6/2003 +0200, Jari Arkko wrote:

[snip]

>    for stateless autoconfiguration are offered."

Do you suggest this text in addition to or replacing the following text 
from my original draft:

   An
   IPv6 node that does not include an implementation of DHCP will be
   unable to obtain any IPv6 addresses aside from link-local addresses
   when it is connected to a link over which it receives a router
   advertisement with the 'M' flag (Managed address configuration) set
   and which contains no prefixes advertised for Stateless Address
   Autoconfiguration (see section 4.5.2).

- Ralph

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From: Jari Arkko <[email-masked]>
Date: Thu, 06 Feb 2003 16:23:46 +0200

Ralph, your text is fine. I didn't realize you already
had it there. Anyway, as long as a note roughly with
the contents we have been discussing appears, I'm OK
with it...

Jari

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From: Ralph Droms <[email-masked]>
Date: Thu, 06 Feb 2003 10:17:58 -0500

Jari - I liked the way your text was explicit about the consequences of not 
obtaining a global address through DHCP when no stateless autoconfig 
prefixes are advertised:

    Nodes that do not implement DHCP may become unable to
    communicate outside the link when their routers advertise
    stateful autoconfiguration and no prefixes suitable
    for stateless autoconfiguration are offered.

Not knowing the background of all readers of the doc, it might be good to 
put your explicit warning in the text:

   An IPv6 node that does not include an implementation of DHCP will be
   unable to obtain any IPv6 addresses aside from link-local addresses
   when it is connected to a link over which it receives a router
   advertisement with the 'M' flag (Managed address configuration) set
   and which contains no prefixes advertised for Stateless Address
   Autoconfiguration (see section 4.5.2).  In this situation, the IPv6
   Node will be unable to communicate with other off-link nodes.

And, I can live with MAY as long as this text is included.

- Ralph

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From: Roy Brabson <[email-masked]>
Date: Fri, 7 Feb 2003 11:07:13 -0500

>    Node will be unable to communicate with other off-link nodes.

This isn't strictly true - a node may use manually configured global or 
site-local IPv6 addresses and still be able to communicate with off-link 
nodes.  Maybe the first sentence should be updated to indicate the node 
will not be able to dynamically obtain any IPv6 addresses, as an IPv6 may 
be statically assigned to a node, and the last sentence to indicate a node 
will require manual configuration in the absence of DHCP support when 
Stateless Address Autoconfiguration is not being used?  Something like:

   An IPv6 node that does not include an implementation of DHCP will be 
   unable to dynamically obtain any IPv6 addresses aside from 
   link-local addresses when it is connected to a link over which it 
   receives a router advertisement with the 'M' flag (Managed address 
   configuration) set and which contains no prefixes advertised for 
   Stateless Address Autoconfiguration (see section 4.5.2).  In this 
   situation, the IPv6 Node will be unable to communicate with other 
   off-link nodes unless a global or site-local IPv6 address is 
   manually configured. 

Roy

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From: Ralph Droms <[email-masked]>
Date: Fri, 07 Feb 2003 13:36:08 -0500

Roy - thanks for noticing the omission of manually configured 
addresses.  Your revised text looks fine to me.

- Ralph

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From: "Fred L. Templin" <[email-masked]>
Date: Mon, 10 Feb 2003 10:34:56 -0800

Roy et al,

I wonder if the setting of the "L" bit in Prefix Information options
also bears some mention in this section. RFC 2461, section 4.6.2 says:

   "When (the L bit is) not set, the advertisment makes no statement
    about on-link or off-link properties of the prefix. For instance,
    the prefix might be used for address configuration with some of
    the addresses belonging to the prefix being on-link and others
    being off-link."

Does this mean that prefix information options with the L bit not
set can be used to auto-configure off-link global or site-local
addresses?

Thanks,

Fred Templin
[email-masked]

Roy Brabson wrote:
>>Not knowing the background of all readers of the doc, it might be good 
> 
> to 
>

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From: JINMEI Tatuya / 神明達哉 <[email-masked]>
Date: Sun, 16 Feb 2003 16:47:26 +0900

>>>>> On Mon, 10 Feb 2003 10:34:56 -0800, 
>>>>> "Fred L. Templin" <[email-masked]> said:

> set can be used to auto-configure off-link global or site-local

I don't think so.  The L bit is irrelevant to address configuration.

					JINMEI, Tatuya
					Communication Platform Lab.
					Corporate R&D Center, Toshiba Corp.
					[email-masked]
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