Subject: WG Action - 1 week last call [LL15] Algorithm for claim/defend will break if multiple interfaces

From: Erik Guttman <[email-masked]>
Date: Thu, 3 Apr 2003 18:19:46 +0200 (CEST)

This item is entering a 1 week last call discussion period, ending Apr
10, 2003.  Please send a comment to the working group list indicating
whether you accept or reject the proposal, including more information if
appropriate.  Please use the subject line:

  [LL15] Algorithm for claim/defend will break if multiple interfaces

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Please consider LL30.  If we accept LL30, then this issue should
be rejected.
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Description of Issue  Algorithm for claim/defend will break if multiple
interfaces are connected to the same link    
Submitter Name  Erik Nordmark    
Submitter Email Address [email-masked]    
Date first submitted  6 Feb 2003    
Reference
http://www.merit.edu/mail.archives/zeroconf/2002-10/msg00000.html
Comment Type ['T'echnical | 'E'ditorial]  T    
Priority['S' Must fix |'1' Should fix | '2' May fix ]  S    
Section  3.2
Rationale/Explanation of issue:   

Lengthy description of problem:

section 3.2

In addition, this kind of host should probe for, and defend, all of its
link-local addresses on all of its active interfaces that are using
link-local addresses. 

When bringing up a new interface, the host SHOULD first probe for all of
its existing link-local addresses on that new interface.  If any of the
addresses are found to be already in use by some other host on that new
link, then the interfaces in question MUST be reconfigured to select new
unique link-local addresses. The host should then select a link-local
address for the new interface, and probe on all of its active interfaces
to verify that this new address is unique on all the links that the host
has connections to. 

The above breaks if multiple interfaces on the host are connected
to the same link. It also isn't clear to me why this is needed;
presumably the interfaces can be managed indepdently as long as the host
ensures that it doesn't assign the same link-local address to more than
one interface.

Erik Guttman suggests

Each interface should be assigned a different v4LL address and can then
operate independently. 

Requested Change:  

Replace Section 3.2 text with

A host MUST run the address selection and defense algorithm distinctly
on each interface supporting IPv4 link-local configuration.  This
ensures that in the case where more than one of the interfaces are on
the same link the algorithm will terminate.  Otherwise, the host may
detect collisions from its own allocations and cause the claim and
defend algorithm to fail.

Erik Guttman
Zeroconf WG chair

---

From: Erik Guttman <[email-masked]>
Date: Fri, 11 Apr 2003 14:54:57 +0200 (CEST)

Action: Accept

Erik Guttman
Zeroconf WG chair

On Thu, 3 Apr 2003, Erik Guttman wrote:
> Subject: WG Action - 1 week last call [LL15] Algorithm for claim/defend will break if multiple interfaces
> 
> 

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