Subject: RE: ZMAAP changes

From: Peter Johansson <[email-masked]>
Date: Wed, 28 Mar 2001 09:32:22 -0800

At 11:53 AM 3/28/01, Mayer, Jim wrote:

>It seems to me that a practical protocol along the lines of the following 
>could be developed:
>
>(1) AIU messages contain an address, an ID, and an "assertion time."
>
>(2) The "assertion time" is a hint indicating that some mini-MAAS believes 
>that it will need the address for at least the stated time.  An system 
>where all mini-MASSs advertised an assertion time of zero would be 
>equivalent to Erik Guttman/Stuart Cheshire proposal.
>
>(3) If a mini-MAAS maintains an AIU cache, and if an AIU for a cached 
>address/ID is received, then the only effect is to (possibly) extend the 
>"assertion time" of the cache entry up to some (modest) maximum.
>
>(4) If a mini-MAAS that would normally be defending an address (e.g., 
>"like the allocator and any mini-MAAS which has had an application 
>register interest in the allocation") noticed that the "assertion time" 
>was "about to" expire, it would issue a new AIU.  The definition of "about 
>to" would be something like "reached a randomly selected percentage (say, 
>from 60 to 90 percent) of the AIU lifetime".

This is similar to the resource allocation protocol (MCAP) described in RFC 
2734. I think it has similar merits.

The assertion time is particularly useful if there is to be an orderly 
transition from "ownership" by one mini-MAAS to another in cases where the 
current owner no longer intends to defend the address. Because multicast 
set-up and tear-down times can be significant and perceivable by a user, I 
think the protocol should permit transfer of ownership.

Although RFC 2734 may not be literally applicable to your situation in Zero 
Configuration, we had to contend with like problems of distributed 
ownership and coordination. The MCAP protocol deserves your examination.

Regards,

Peter Johansson

Congruent Software, Inc.
98 Colorado Avenue
Berkeley, CA  94707

(510) 527-3926
(510) 527-3856 FAX

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