The HNMS+ System
The HNMS system prototype version was developed to cover the network management needs that arose because of the continuing installation of large, high speed local and wide-area networks for the Numerical Aerodynamic Simulation (NAS) Faculty at the NASA Ames Research Center . This prototype version of HNMS is available on the Internet.
The prototype version of the available HNMS consists of two types of modules, which typically reside on separate hosts throughout the network. The Server module is the hub for the network data; it provides a center for dissemination of global topology and status information. The User Interface (UI) module resides on workstations with graphics capabilities and provides access to real-time or logged data. All inter-module communication is done using the Hierarchical Network Management Protocol (HNMP) described in .
The protocol requires the use of new HNMS MIB, which defines a set of variables in addition to standard SNMP variables[6,16]. HNMS MIB objects represent IP network elements within HNMS system. Each object is identified by a unique number, its HNMS id, which is assigned by the server. Objects belong to one of the following classes which represent network entities or other useful information about network management: Internet, Network, Subnet, Interface, Processor, Site, Equipment, Administrator, or Address.
Figure 1.: ScreenShot of a Typical Administration Terminal
HNMS provides four types of status diagrams, each representing the view of state of a network element using a colour code. These diagrams are updated by the server, reflecting changes of the element's status. The WAN diagram depicts the state of the IP network and the routers over a geographical reference (e.g. a map of Ukraine). The Site diagram represents all LANs that are connected to the routers at a given site. The Custom diagram allows the user to construct a diagram with any set of network elements he wishes to observe. Finally, the Object diagram is a textual display of the HNMS variables.
Although Input/Output (IO) modules were mentioned in the general architecture of HNMS, the prototype version did not support multiple IO modules, and as a consequence, there was no true hierarchy in its structure. Therefore, the implementation of IO module functionality was necessary to collect local information about the behaviour of particular subnetworks that are compound parts of National Network of Ukraine. The IO modules reside on hosts located at strategic points within WAN (regional, district, metropolitan-area subnetwork) and handle actual data collection.
Our IO modules use SNMP [6,16] protocol for local data collection from the SNMP agents attached on the actual network devices. These modules pass filtered management data, up to the server module. In accordance with the overall architecture of HNMS, data are sent from IO to servers only when their values change. Thus the hierarchical installation of IO modules allows to avoid flooding the network with management traffic and creating bottlenecks when management information is directed to ExperNet agents. The new HNMS is named HNMS+ and it is a true hierarchical distributed system which fully supports HNMS functionality and extends it with new features.
Additionally, the fourth type of module mentioned in the HNMS external specification, the database module, was developed. The database module is an SQL front-end process that stores HNMS+ MIB variable values in a PostgreSQL database with a frequency given by the user (usually approx. 1 minute). The database module interacts with the HNMS+ server/IO module store only when variables of local server/IO modules change in order to avoid network overloading by SQL requests. Finally, an interface of the ExperNet agents with HNMS+ was implemented in CS-Prolog II as a special Knowledge-based intelligent processing (KBIP). The KBIP module is an application that obtains, through HNMP protocol, information about network traffic and utilisation of the network elements.
On each node HNMS+ provides to the ExperNet agents an immediate perception of the state of network. Using KBIP modules, ExperNet agents not only are able to immediately determine the general state of the network but also be notified by HNMS+ about important network events.