Re: M2PA BSN dis-ordering

Thanks Brian

    For the details. But on my point of view the first DATA with FSN = 4 and 
BSN =12 is valid one and endpoint B flushes all the packets upto FSN = 12 at 
its side. So when it again receives a packet with FSN=5(correct) and 
BSN=11(incorrect i.e. already flushed) then this packet will be ignored.

    As per you both the packets are invalid? Or only last packet is invalid. 
kindly clarify this.

Regards,
Bibhuti Bhusan Tosh

----- Original Message ----- 
From: "Brian F. G. Bidulock" <[email protected]>
To: "Bibhuti Bhusan Tosh" <[email protected]>
Cc: <[email protected]>
Sent: Friday, May 26, 2006 1:50 PM
Subject: Re: [Sigtran] M2PA BSN dis-ordering


> Bibhuti,
>
> If you are following Q.703, the handling is per that standard.  One
> isolated abnormal BSN is ignored, but two consecutive abnormal BSNs
> cause the link to be put out of service.  So at the end of your sequence
> B sends FSN=14 BSN=4 and FSN=15 BSN=5, however, if another abnormal BSN
> follows, OUT-OF-SERVICE is sent from B.
>
> You can see this in test cases 3.8.10 and 3.8.11 in
> draft-bidulock-sigtran-m2pa-test-06.txt and in Q.781/Test 8.10 and
> Q.781/Test 8.11.  T7 is not impacted by the abnormal BSN per the Q.703
> SDLs because the abnormal BSN does not negatively or positively
> acknowledge any message.
>
> But this is defined by SS7 MTP2 and not altered by M2PA: therefore, it
> is of some advantage to learn how a traditional SS7 link works before
> working with M2PA.
>
> --brian
>
> Bibhuti Bhusan Tosh wrote:             (Fri, 26 May 2006 11:09:32)
>>
>>    Hi All
>>
>>
>>
>>    Kindly  consider  the following call flow and suggest me for the valid
>>    FSN and BSN values.
>>
>>
>>
>>      A    B
>>    ---------------------------- ----------------------------
>>
>>
>>
>>    MTP3  M2PA  SCTP                   SCTP  M2PA  MTP3
>>    ----  ----  ----                  ----  ----  ----
>>
>>
>>
>>    User Data FSN=1 BSN=10 . .
>>         ------------------------------------> . .
>>    User Data FSN=2 BSN=10 . .
>>         ------------------------------------> . .
>>    User Data FSN=3 BSN=10 . . . .
>>         ------------------------------------> . .
>>                                  User Data FSN=11 BSN=3 . .
>>         <------------------------------------ . . . .
>>                                  User Data FSN=12 BSN=3 . .
>>         <------------------------------------ . . . .
>>                                  User Data FSN=13 BSN=3 . .
>>
>>         <------------------------------------ . . . .
>>    User Data FSN=4 BSN=12 . . . .
>>         ------------------------------------> . . . .
>>                                  User Data FSN=? BSN=? . .
>>         <------------------------------------ . . . .
>>    User Data FSN=5 BSN=11 . . . .
>>         ------------------------------------> . . . .
>>                                  User Data FSN=? BSN=? . .
>>         <------------------------------------ . . . .
>>
>>        Is there any impact of T7 timer expiry?
>>
>>
>>
>>    Regards,
>>
>>    Bibhuti
>
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>
> -- 
> Brian F. G. Bidulock
> [email protected]
> http://www.openss7.org/