OpenView snags network routers

OpenView snags network routers

Hewlett-Packard's OpenView Network Node Manager has a problem: a network discovery feature that can cripple routers.

Users report that when NNM polls routers, its netmon discovery feature requests routing tables in the router. If the router keeps a lot of routes in its table, the box will expend most of its power to meet netmon's request, leaving little left to process traffic.

NNM is HP's core network management platform; it automatically discovers devices throughout a network, collects network events and analyses trends. Detractors have criticised NNM in the past for its inability to handle management tasks in larger enterprises. HP has attempted to address this issue in previous releases, including the "Tornado" release in 1996, which distributed some of the functions of NNM among servers.

Had to reconfigure

"We had to reconfigure netmon to turn this function off," says Wayne Harriman, product owner of network management systems at Charles Schwab. A few months ago, the company noticed CPU utilisation topping 90 per cent on a Cisco 7500 router and traced the problem to netmon. Since the company reconfigured netmon, it hasn't encountered that problem and it hasn't missed the discovery feature. Several users have complained of similar problems in recent weeks on the OpenView Forum's e-mail group.

Disabling the function is a simple process, but NNM won't be able to discover as many new nodes, says Reid Shay, HP's business development manager for NNM. The netmon component downloads the routing tables to find links to routers that don't communicate using IP addresses, he says. Two routers of the same make - such as two Cisco routers or two of Nortel's Bay routers - will often communicate on another level, Shay says.

The discovery technique has been used by HP OpenView software for eight years. However, users are starting to have difficulties now because of increased Web traffic, Shay suggests.

A router directing traffic to Web servers may build a large routing table because it will be transmitting data from many places, inside and outside of a company's network. This is different from networks in the past, which may have only managed communications inside the company.

One user who told the OpenView Forum of performance degradation in a Cisco 7513 router says its routing table contains 50,000 routes.

The problem with OpenView and other network management platforms developed earlier in the decade is that they weren't built with scalability in mind, says John McConnell, president of consulting firm McConnell Associates in the US.

He notes that HP has said it will bring together its various network management technologies to create such a multi-tier structure by mid '99.

Such a structure would have regional management servers reporting back to central managers, to break up the management load while sending data back to all levels of the hierarchy that need it.

Users have complained that it can take a lot of processing power and memory on the OpenView NNM workstation to get the polling function to work.

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