Moby Dick Consolidated System Integration Plan

D0103v1.doc Version 1 6.7.2003
course, the accounting data needs to contain information about roaming, in order to allow the charging
component selecting different tariffs (i.e. roaming tariffs).
4.5.4.1 DIAMETER Messages vs. Entries in the Accounting Database
In this context, three kind of DIAMETER messages are of interest: “start”, “interim” and “end” messages.
When a session starts, the DIAMETER “start” message will add the first row of the current session to the
accounting database. This first row is mandatory. Section 0 describes in details how the parameters have
to be defined. When a session is running, DIAMETER “interim” messages are being generated. When a
session ends, a DIAMETER “end” message will be generated and the last row for this current session will
be added to the accounting database. This last row is mandatory like the first row.
It is important that the accounting database is consistent! It’s up to the accounting system, to ensure the
consistency. Therefore, accounting for the current session x has to produce the following entries in the
accounting database:
“start” message => first row for session x
“interim” messages
“end” message => last row for session x
Therefore, accounting for a session x, will at least yield to two rows in the accounting database 1 .
4.5.4.2 Sessions
Moby Dick uses the concept of sessions. The next subsections give some more details about the (Moby
Dick) session concept. In general, each session is defined with a unique session ID and is associated with
a user.
Note: It is possible that a user can have more than one open session.
4.5.4.2.1 Start of a Session
A session can start after the following two events:
1. A user switches on his MN and requests authentication and authorization. After successfully
passing AA, the user will be associated with a session ID.
2. A user moves from one AR to another, i.e. handover takes place. The “new” AR will associate a
new session ID to the user.
3. A new user logs in a MN.
All events will yield to a DIAMETER “start” message and will eventually define the first row of a session
in the accounting DB.
Note: When the user starts a new application (e.g. VoIP) within a current session, then there will be new
flows set up (with certain DSCP values), but not a new session.
It is possible that two different applications generate flows with the same DSCP values; therefore it is not
possible to conclude from an observed flow (i.e. the accounting data in the DB) to a certain application.
4.5.4.2.2 Termination of a Session
A session will be terminated after the following three events:
1. A user switches off his MN.
2. A user moves from one AR to another, i.e. handover takes place. The “old” session from the
previous AR has to be closed.
3. The lifetime of a session is reached, cf. section 4.5.4.2.4.
All events will yield to a DIAMETER “end” message and will eventually define the last row of a session
in the accounting DB.
It is important to note that only closed sessions will be used for the charging process, cf. section 4.5.4.2.5.
1 If the duration of a session is shorter than the interval of diameter „interim“ messages then the accounting DB will
contains only two rows.
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