SNT Service Levels Performance
Service levels are best analyzed in relation to an installation-defined set of service level objectives.
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Network service levels are areas of prime concern to the management of the installation as a whole, and particularly to the network management staff, because service levels measure how efficiently and effectively network facilities are delivered to the end user.
Service level objectives may be set in different ways based on criteria that are often unique to the installation and depend on its organization, management objectives, and financial considerations. Several types of objective strategies are discussed below.
Host Service Objectives
Before the availability of end-user response time measurements, host service objectives were the only available management indicators of communications effectiveness. Tivoli's NetView Performance Monitor and
NetSpy
make it possible to measure host response time separately from network response time, thus allowing host response objectives to be retained. The advantage of defining separate host service objectives is that they can identify developing host service problems even when end-user response time is within the overall objectives. Generally, host service objectives are set on an application-by-application basis because each application has different host processing resource requirements.Network Service Objectives
Network service objectives define the requirements for delivery of service outboard of the host processor. These objectives are of considerable interest because, until recently, this information was largely unavailable. Network service objectives must be set regarding network considerations rather than existing host-processor considerations.
Two general classifications of network service are reasonable
Topology Based
- Communications path design constraints
- Media type constraints
- local versus remote
- link speed
- multi-drop versus dedicated link
- satellite versus land line
Resource Based
- Class of service as defined by network tuning parameters
- Volume of data transmitted
End-user (total) Service Objectives
In general, total service objectives should be close to the sum of the applicable network and host service objectives for each breakdown of network traffic. Neither Tivoli's NetView Session Monitor nor
NetMaster
NTS measures host and network response time independently. They each allow all of the variations mentioned above to be accommodated through the use of installation-defined performance classes. NetView performance class definitions and NetMaster
NTS RTM class definitions should be carefully evaluated based on the considerations mentioned above.The following sections suggest key data elements, exception conditions, component reports, and sample analyses which may be helpful in the management of performance levels: