[AVT] CAS signalling events: draft-ietf-avt-rfc2833biscas-00.txt

[Tom Taylor <taylor at nortel.com>]

I have just submitted draft-ietf-avt-rfc2833biscas-00.txt to capture the 
trunk-oriented signalling events from RFC 2833, as modified in earlier 2833bis 
work.  There are some key deviations from the events as presented in 
draft-ietf-avt-rfc2833-05.txt.  These have to do with line event signalling for 
signalling systems No. 5, R1, and R2, and the mapping of ABCD bits to event codes. 
 The new mappings are my best attempt at consistency with published documents.

The basic mapping of ABCD states to event codes was changed when I found a 
PacketCable specification using some of those events from RFC 2833.  It appeared 
that they assumed a mapping where the A bit is the high-order bit of a 4-bit 
state, where draft-ietf-avt-rfc2833-05.txt suggested that the A-bit would be the 
low-order bit.  I changed the text to be consistent with the PacketCable mapping. 
 However, the R2 line code mappings are a bit ugly as a result, with the event 
codes differing for the same line state depending on whether analog or digital 
line signalling is being used.

Could anyone who has used the ABCD events in the past look over the document to 
see if it still works for them?

--
Tom Taylor
Carrier VoIP Standards Development
Nortel
Phone +1 613 763 1496  (ESN 393-1496)
E-mail: taylor at nortel.com

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