Subject: [manet] Re: Comments about draft-ietf-manet-packetbb-04

From: Thomas Clausen <[email-masked]>
Date: Thu, 14 Jun 2007 18:52:36 +0200

Charlie,

Allow me to add a few clarifying comments below.

On 14May , 2007, at 7:04 PM, Charles E. Perkins wrote:

> Whether or not multiple addresses are collected is dictated by
> the meaning of the message, not the desire for a person to save
> space according to a parseable bucket of message fields.
> I agree that when you can collect multiple addresses, the
> more you can get the less percentage overhead will be
> incurred for the whole collection.

A message, as defined by packetbb, contains a set of addresses, with  
each address associated with zero or more attributes. Attributes are  
associated with addresses through the use of address block TLVs.  
There is no positional semantics of a given address being in one  
rather than the other address block.

Let me examplify, and let's assume that addresses can be "red",  
"greeen" or "blue". You could then:

	(1) 	collect all red addresses in one address block, and associate
	  	an address-block TLV saying "Red" to this address block

	  	(and, obviously, the same for "Green" and "Blue", leaving you
	  	with one address block for each color)

	(2)	collect all addresses into one or more address blocks in order  
to obtain
		the most efficient aggregation, and associate either a single multi- 
value
		address-block TLV saying "Red", "Green", and  "Blue" for the  
appropriate
		addresses, or associate multiple indexed  address block TLVs  
indicating
		"Red", "Green" or "Blue" as appropriate to these address blocks.

Depending on how well addresses aggregate, either of these may be  
more efficient than the other.

I think that it would be clever to pick the most efficient  
aggregation of addresses. But, if you would, for a specific protocol,  
want to collect "only RED addresses" in this address block,  
aggregation-efficiency be dammed, then you could of course do so.  
That would then, be for that protocol using packetbb to specify.

In other words, addresses are collected into address blocks in order  
to obtain the most efficient aggregation, and are associated with  
attributes through TLVs -- not through being in this, that or the  
other address block.

So, I think that I will draw the conclusion that what you are  
suggesting (that a protocol MAY specify that addresses to be  
collected into the same address block are somehow related by having  
common attributes) is fully supported by packetbb, as is the ability  
to collected into address blocks for the most efficient aggrgation  
fully supported by packetbb.

-- 
Thomas Clausen
[email-masked]
http://www.thomasclausen.org/

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