Re: M2PA questions on synchronization and message handling

Dario,

Dario wrote:                                   (Thu, 20 Dec 2007 04:29:35)
> 
> OF course the sequence numbers do not need synchronization since there were
> no
> User Data messages exchanged at that point.
> But my questions are the following:
> - is the sequence of messages for synchronization the same in Initial
> Alignment as in stable PO state:
>   LS Processor Recovered ->
>   LS Ready (1) <-
>   LS Ready (1) ->
> 
> - how these messages collide with Link Status messages (for example, LS
> Ready on stream 0) and what are the consequences?

See test cases 3.1.11, 3.1.12, 3.1.13, 3.1.14, 3.1.15, 3.1.16, 3.1.35,
3.2.1, 3.2.2, 3.2.3, 3.2.4, 3.2.5, 3.2.6, 3.2.7 in the test suite
draft-bidulock-sigtran-m2pa-test-08.txt for examples.

> 
> not if they are connected:
> 
> 1. message is received with invalid BSN. This message wil be discarded
> 2. User Data message is received with FSN=x, valid, but it should be
> discarded according to Q.703 statement above.
> 3. User Data message is received with FSN=x+1. This is unexpected FSN and
> the message will be discarded....and so on.
> 
> finally ack timer will expire and the link will go Out of Service.

The peer violated the protocol at 1.  (The rest is just one possible
result of that.)  You should not find it surprising that signalling
links fail to operate and eventually find themselves in the out-of-
service state when one side refuses to follow the protocol.

--brian

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