The major commercial software vendors, known as the "big four," are frequently criticized for their high cost and complexity and, in some cases, are chided for being too robust -- having too many features that some enterprise users may find completely unnecessary.
Many of the open source alternatives are quick to admit that their solutions aren't for everyone, but they bring to the table arguments in their favor that networking pros can't ignore, namely low cost and ease of use.
"Open source is a huge phenomenon," Zenoss CEO and co-founder Bill Karpovich said. "It's providing an alternative for end users."
Zenoss makes Core, an integrated IT monitoring product that lets IT admins manage the status and health of their infrastructure through a single Web-based console. The latest version of the free, open source software features automated change tracking, automatic remediation, and expanded reports and export capabilities.
According to Karpovich, Zenoss software monitors complete networks, servers, applications, services, power and related environments. The biggest benefit, however, is its openness, meaning that users can tailor it to their systems any way they choose.
"It's complete enterprise IT monitoring," Karpovich
Some users have said the Tivolis and OpenViews of the world are hard to customize and very inflexible, but open source alternatives are often the opposite. They are known for their flexibility. "You can use the product as you want," Karpovich said.
Nagios developer Ethan Galstad said flexibility is a major influence on enterprises looking to move ahead with an open source monitoring project. Nagios makes open source software that monitors network availability and the states of devices and services.
"You have as an end user much more influence on the future of the feature set," Galstad said, adding that through the open source community, end users can request a feature they want, discuss the pros and cons and, in many cases, implement that feature within a relatively short time.
And for things that Nagios and other open source monitoring tools don't do, end users can tie the tools in with other solutions to create the environment they want.
"There are a lot of hooks," Galstad said.
Galstad agreed, adding that enterprises can save a bundle on licensing fees by implementing open source monitoring tools
Along with Zenoss and Nagios, other open source network monitoring and management tools are gathering steam. The likes of Groundwork OpenSource, Hyperic and Qlusters offer open source alternatives. Some vendors have gained enough popularity that they are now being billed the "little four."
Karpovich is quick to note, however, that the "little four" designation doesn't necessarily mean the vendors offer as much functionality as their non-open rivals. He plays by the "80-20 rule."
"We'll do 80% of what they do," he said. "We never do everything they do because a lot of it is irrelevant."
Ofer Shoshan, founder and CEO of Qlusters, maker of OpenQRM, an open source application and network management and monitoring tool, said recent interest in open source comes from growth in the industry and tools that can handle bigger deployments.
"In the past, most of the open source tools were aimed at small installations; they were not enterprise grade," Shoshan said. "They were unreliable, unstable and couldn't manage large numbers of systems."
Support is an issue
Some open source monitoring tools offer a level of support now and can support large installations, but still there is some level of apprehension on the part of network pros that putting an open source -- instead of commercial -- tool in charge of their monitoring may not be the best choice, mainly because of a lack of service and support.
"No serious CIO would risk his job deploying a solution that doesn't have service and support," Shoshan said. "He would have to be crazy. And many open source solutions out there didn't have enterprise-grade support and service."
Galstad added that this lack of a "security blanket" could prompt some end users to shy away from open source alternatives.
"There is no one person or one company to choke if something goes wrong," he said. "You might not be able to get the help that you need."
"But for those who are willing to do a little research and work on their own," Galstad continued, "they're much more comfortable with digging into the problem and finding a solution."