Ethereal-dev: Re: [Ethereal-dev] Need help with protocol that spans multiple TVBs

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From: "Sid Sid" <ysidelnikov@xxxxxxxxxxx>
Date: Tue, 13 Apr 2004 12:30:11 +0000
Be careful. I believe that it is presentation (e.g. the PDV lists of the P-connect) that decide the dissector to be called from within ACSE. A close inspection would yeild that the PDV lists contains two(2) OIDs (e.g. one for ACSE and the other for MMS/FTAM etc...). Addtionally, the order of the PDVs is not guaranteed (e.g. MMS could occur before ACSE).
As I can see the order is really guaranteed because ACSE protocol is using only for connect/disconnect/abort etc. 
For example, for connection:
TPKT
COTP
Session connection request pdu
Presentation connection request pdu
ACSE A-associate request with OID for top level.
MMS/FTAM/CMIP etc.

For data block it is working without ACSE level:
TPKT
COTP
Session given token/Data transfer pdus
MMS/FTAM/CMIP etc.
The problem wiil be if we have MMS and for example, FTAM independent and simultaneous data exchanges. 
For example:
ACSE for FTAM
Data for FTAM   -> will go to FTAM dissector
...
ACSE for MMS
Data for MMS
...
Data for FTAM   -> will go to MMS dissector.
The solution could be to keep calling and called pair of presentation selectors along with OIDs. 

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