Subject: RE: SDH Format

From: "Brungard, Deborah A, ALABS" <[email-masked]>
Date: Fri, 11 Feb 2005 09:10:39 -0600

I will answer briefly - if you need more info, contact off-line:
 
Both ETSI and ANSI were developed in parallel, ETSI is based on AU-4,
and ANSI is using both AU-3 (for G.707's VC-3 payloads) and AU-4 (for
G.707's C-4 payloads). ITU's agreement was to use ETSI's SDH name (vs.
ANSI's SONET) and to include both AU-4 and AU-3 structures in Rec. G.707
as "SDH was designed to be universal". And resulting in G.707's rule for
interconnection of the two different types is to use the AU-4 structure
(demultiplexing to either VC-3 or TUG-2 for interconnection). Japan also
uses both the AU-3 and AU-4. Later, ETSI radio applications did define
an AU-3 structure, though I don't know if it is being used.
 
Deborah

  _____  

From: [email-masked] [mailto:[email-masked]] 
Sent: Friday, February 11, 2005 7:47 AM
To: [email-masked]; Brungard, Deborah A, ALABS;
[email-masked]
Cc: [email-masked]
Subject: SDH Format

You guys are the experts behind this and from some thread on the
internet regarding SDH; I just need your help to explain the differences
between AU-4 and AU-3? American versus European or ETSI?

Jerome Law