2. USAGE CONSIDERATIONS › 2.3 Use Within the Information Structure › 2.3.3 Service Level Analysis › 2.3.3.1 Service Levels: Performance › 2.3.3.1.4 Performance Level Analysis

2.3.3.1.4 Performance Level Analysis

 
REPORTING RESPONSE TIME DIFFERENCES FOR VIRTUAL ROUTES
 
While the nodes in the network are physically connected by
real links known as explicit routes, network traffic flows
over logical connections called virtual routes.  These
virtual routes assume the physical characteristics (media
type, reliability, bandwidth, etc.) of the underlying
explicit routes to which they are assigned, but the path
control network schedules message units on a virtual route
based on its transmission priority.
 
When a logical unit to logical unit (LU-LU) session is
established, the session-initiation request identifies a
desired class of service.  The system services control point
(SSCP) looks-up this class of service in the class of service
(COS) table.  The COS table lists virtual route and
transmission priority pairs.  Using the table entry for the
requested class of service, the SSCP assigns a virtual route
and transmission priority for the session.
 
Since the virtual routes and transmission priorities are the
primary means the network analyst has to regulate traffic
flow through the network, knowledge of the service provided
to the end-users communicating over a particular virtual
route at a specific priority is extremely valuable when
maintaining the class of service table.  This information is
available in the CA MICS Network Analyzer's NLDM Service File
by summarizing DETAIL data from the SNTNSV File by virtual
route and transmission priority as follows:
 
    %INCLUDE INCLLIB(%SNTMACS);
    MACRO _BY NSVVRRTE NSVTRPTY %
    MACRO _BREAK NSVTRPTY %
    PROC SORT DATA=_dSNTX.SNTNSV01 OUT=VRSERV;  BY _BY;
    RUN;
 
    DATA VRSERV;  SET VRSERV;  BY _BY;
        _NSVSUM
    RUN;
 
    PROC PRINT LABELS;
    ID  NSVVRRTE;
    VAR NSVTRPTY NSVAVTTM NSVPCTR1 NSVPCTR2 NSVPCTR3
        NSVPCTR4 NSVPCOBM;
    RUN;
 
By determining the actual effect of specifying different
transmission priorities for different virtual routes, the
class of service table can be made to reflect the
organization's business needs more accurately.