Extending the Sample SNMP Programs

The C++ or Java program samples can form the foundation of a more complex product. NMS typically take the form of a server with a number of distinct (possibly distributed) components , such as (in the FCAPS order):

• A fault server that listens for traps from the managed network

• A configuration (or provisioning) server that executes SNMP SET and GET operations

• An accounting server that can apply rules (such as quotas or limits) to specific MIB object counters, such as setting an upper limit on the value of ipInReceives

• A performance server that can perform mediation and also read the various counters supported in the NE MIBs

• A security server that can be used to manage community strings, access control rights, encryption, and authentication details

Figure 7-15 illustrates one such arrangement with a central NMS server and multiple clients. Each client is dedicated to a specific network management function that it executes using the services of the central server. Client 1 is tasked with SLA reporting; that is, it retrieves data from the network relevant to SLAs. This data is then presented as reports , for instance, in HTML format. Client 2 configures the managed NEs by issuing requests (via the central server) to set and get managed objects in the network. Client 3 provides a billing/accounting function ”usually this amounts to reading many objects. Clients 2 and 3 access the server using IPSec, and Client 1 uses HTTPS; all the clients are employing secure communications.

Figure 7-15. Extended snmpmgr.c handles multiple clients.

The important point to note about Figure 7-15 is that it is relatively straightforward to build a complex management system once the basic agent and manager entities are in place. Additional server components are:

• Topology manager to handle icons, network maps, and device status

• An access server that provides a queuing mechanism for handling simultaneous requests from more than one client user (this server could be part of the server in Figure 7-15)

The last two points move us out of the SNMP domain and are included just for completeness.