RMon - network news from afar

RMon - network news from afar

The age of network computing is upon us. Client/server computing has already demonstrated that greater emphasis on the network leads to greater network traffic, as more users access more applications more often.

While there are many tools to help with centrally-based network management, these are often limited to reactive troubleshooting and administration duties.

One technology which claims to go beyond this is the RMon Management Information Base, the Internet Engineering Task Force-developed industry standard for Remote Monitoring of networks across multiple vendor platforms utilising the Simple Network Management Protocol (SNMP) framework. RMon is designed monitor remote devices more efficiently and more proactively than SNMP, with greater scalability. SNMP agents continually gather statistics and record them, and must be polled by network managers to create any form of history for analysis. RMon agents store a history of statistical data at the agent site, removing the need for continual polling to see how the network is performing. They then upload this information to a console for analysis, and are also able to signal an alert when they discover abnormalities on the network.

According to Mike Bell, technology manager at Digital Equipment Corporation's Network Product Business, RMon fills the gaps in conventional SNMP reporting. "Over the years there have been lots of standards for management. SNMP is the one that really caught on and people have liked, but it probably isn't the most efficient, and has lots of holes in it. One of the big holes is that fact that you have to poll equipment, which chews up quite a lot of network bandwidth."

RMon, however, has the ability to alert managers only when it has something it needs to tell them. This is an example application of the original RMon standard, now know as RMon1, which works at the network level only.

According to Bay Networks' network management specialist Leo Risbridger, many managers want to know more than just their network operation status, such as how their applications are being used in the network. Herein lies the domain of a newer standard: RMon2. "RMon2 allows us to move up into the network layer, so rather than just identifying MAC conversations I can start to identify IP and IPX conversations," said Risbridger.

"And then we can move into the network applications, where rather than just looking at individual protocols like IP, I can break it out and look at NFS, WWW, and Telnet traffic, etc." RMon2 is designed to provide additional functions above and beyond RMon1, without actually replacing it.

However, according to UB Networks' technical director, Alan Gray, there is a price to be paid in the amount of strain RMon places on network resources. "To go beyond the first four groups, which are basically statistics gathering, you really need a lot of horsepower available, or a device that's focused on doing nothing else but monitoring and capturing packets and creating log files."

It may sound somewhat daunting, but in the correct application Gray says the benefits of RMon can be many. "It's the value of being able to proactively determine the status of networks and react before the problem manifests itself or becomes too serious. It allows us to go that extra step and start to analyse and 'what if?' the network, to do capacity planning and things like that."

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