Subject: [Softwires] a=0 is outside the scope of the GMA in draft-ietf-softwire-map-02

From: Tom Taylor <[email-masked]>
Date: Mon, 24 Dec 2012 13:57:31 -0500

I hate to raise an old topic, but based on the explanation in the text I 
proposed in my previous note, a is the number of bits required to 
represent the value 65536/(M*R) - 1. Even if this value comes out to 
zero (implying just one block and all ports for a given CE are in a 
single consecutive range), surely one bit is required to represent that 
value. Thus a=0 may be a possible partitioning of the binary 
representation of the port number P, but it falls outside the scope of 
the Generalized Modulus Algorithm.

We are left with the choice of discarding the GMA as an explanation for 
the partitioning of P (leaving a simple procedural declaration in its 
place) or excluding a=0 from the set of possible values of a.

Tom Taylor

---

From: Tom Taylor <[email-masked]>
Date: Sun, 30 Dec 2012 17:05:44 -0500

On thinking it over some more, I realize that a=0 is a valid outcome of 
the GMA. It represents the case of a single block where in which all of 
the ports for each CE are consecutive. The text should note this. I will 
make specific text suggestions in a more extensive E-mail once I deal 
with the individual issues I see in the draft.