Subject: Re: RFC 2732 and Zone IDs

From: Erik Nordmark <[email-masked]>
Date: Mon, 01 Nov 2004 10:38:57 -0800

Margaret Wasserman wrote:

> "I don't know.  A year ago, I would have said "no", but with documents 
> on the IESG agenda like draft-black-snmp-uri-08.txt, I am taking a new 
> view of URIs.  This document defines a URI syntax that can be used for 
> access to SNMP objects, and one of the use cases includes having a local 
> SNMP manager that is accessed through a URI -- the URI then being 
> translated into an SNMP request that is sent to the agent via SNMP.
> 
> So, URIs can, effectively, be used as a programmatic interface to other 
> applications running on the local system.  In that sort of case, I think 
> we very well might need to include scoped addresses in URIs.  And, IMO, 
> it would be better to have a standard way to do this than to live in a 
> world where folks just insert an unencoded % and some parsers pass it 
> through cleanly, others escape it for you and still others return an 
> error -- which is how the current behaviour of URI parsers has been 
> described in this thread."

I agree that URIs with literal addresses and zoneids could be made to 
work within the local system.

But, since the zoneid is a local id with no global meaning, having such 
URIs leak outside the local system would potentially cause less things 
to work.
For example,
	machine A assigns zoneid 1 to the one ethernet and zoneid 2 to
	another ethernet for the like-local zones

	machine B has only on NIC and assigs zoneid 1 to it.

	The NIC on B is on the Ethernet which attaches to the zoneid 2
	NIC on A.

Without zonids in the URL, B can handle a URL with a literal link-local 
IPv6 address generated by A, because it only has one link-local 
interface which happens to connect to A.

But if you where to put zoneids in the URLs, then in this case B would 
see a URL with a literal link-local IPv6 address *and* zoneid=2. Would B 
then conclude that it can't talk to it because the zoneid doesn't match?

*If* there is utility of such URLs on the local system, wouldn't we need 
to say that a zoneid in a URL should be ignored except if the IP address 
is indeed an IP address of the host itself?

     Erik

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---

From: JINMEI Tatuya / 神明達哉<[email-masked]>
Date: Wed, 03 Nov 2004 04:57:03 +0900

>>>>> On Sat, 30 Oct 2004 11:54:26 -0400, 
>>>>> Margaret Wasserman <[email-masked]> said:

> "I don't know.  A year ago, I would have said "no", but with 
> documents on the IESG agenda like draft-black-snmp-uri-08.txt, I am 
> taking a new view of URIs.  This document defines a URI syntax that 
> can be used for access to SNMP objects, and one of the use cases 
> includes having a local SNMP manager that is accessed through a URI 
> -- the URI then being translated into an SNMP request that is sent to 
> the agent via SNMP.

> So, URIs can, effectively, be used as a programmatic interface to 
> other applications running on the local system.  In that sort of 
> case, I think we very well might need to include scoped addresses in 
> URIs.  And, IMO, it would be better to have a standard way to do this 
> than to live in a world where folks just insert an unencoded % and 
> some parsers pass it through cleanly, others escape it for you and 
> still others return an error -- which is how the current behaviour of 
> URI parsers has been described in this thread."

In case I misunderstood the scenario, please let me check.  Are you
talking about a scenario where a "client" passes a URI to an SNMP
manager including an IPv6 link-local address with a zone ID for the
client, and the manager then parses the URI and sends a corresponding
SNMP request?  If so, it's an unintended (or even prohibited) usage 
in the current IPv6 scoped address architecture due to the "locality"
reason Erik pointed out.

Of course,

- whether it's worth standardizing the URI notation with zone IDs for
  a pure local usage is a separate question.
- whether we should even more explicitly prohibit such usage (as Pekka
  indicated) is also a separate issue.

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

---

From: Juergen Schoenwaelder <[email-masked]>
Date: Tue, 2 Nov 2004 21:35:54 +0100

> in the current IPv6 scoped address architecture due to the "locality"

Well, I can imagine situations where SNMP URIs are exchanged on a local
system because the discovery management application wants to pass info
to the data collector application about agents discovered in the network.
(I am sure you can find more interesting examples.)

So in general, I think one can make a point that zone IDs in ULRs do 
make sense. But, perhaps the approach to take at this point in time is
just to acknowledge URIs do not support zone IDs and leave this for
future work once we know this is a real problem.

/js

-- 
Juergen Schoenwaelder		    International University Bremen
<http://www.eecs.iu-bremen.de/>	    P.O. Box 750 561, 28725 Bremen, Germany