Subject: Re: m2pa header

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Mon, 27 Aug 2001 14:21:36 -0500

Wayne,

The LI and particularly the LI-spare bits when used by TTC as MP bits,
*are* the data payload.  The LI byte *is* aligned on a 2-byte boundary.
This is no different than low-speed SS7 links which have two bytes
(BSN/BIB, FSN/FIB) before the LI bits.  This is completely consistent
with SS7 message parsers which expect LI on a 2-byte boundary just as
with SS7.

The LI bits themselves may be rather useless (the Common Message Header
length indicates more definitively the length of the MSU), but it is the
LI spare bits which are interpreted as part of the MSU for TTC.

Because the alignment of the MSU is the same as for low-speed links (at
least 2-byte boundary if not 4-byte boundary), there should be no
processor architecture performance impact when compared to existing SS7
link types.

--brian

wayne n taylor wrote: (Mon, 27 Aug 2001 14:58:30)
>
> everyone,
> 
> the length indicator field that follows the m2pa common header causes
> the message data to start on an odd byte boundary. starting data on an
> odd byte boundary can be less than optimal for some machine
> architectures. one proposal to eliminate starting on an odd byte would
> be to add a pad byte.  another option would be to make the li field
> two bytes (expanded li field) ??
> 
> wayne t
> 

-- 
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/

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