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Here are some examples of service monitoring packages, listed from the primitive to the sublime:
So when do you use pollsters rather than SNMP managers? It depends on what you need. In my experience, only larger shops tend to use the SNMP managers; they tend to be expensive, resource intensive, and complex to install and maintain.
Of course, SNMP managers also provide you with lots of information. In particular, the SNMP managers will provide you service-level informationthat is, not only will they tell you whether the resource is up but also how fast it responds, how many bytes of resources are left, and so on. This makes SNMP managers very valuable if youre looking to optimize your network. SNMP managers are excellent for keeping long-term track (baselining) of how your network and resources look on a normal day. As youll see in Hour 23, baselining is a very important part of problem determination when, as they say, The network is slow! After all, if you dont have a sense of how things typically are, how can you tell when something is out of range? Long-term service-level record keeping is also a way to knowand a way to show your bossthat everything is operating efficiently and is working properly.
Still, simple network polling packages can be extraordinarily effective, even for large shops, but particularly for smaller shops. Theyre typically inexpensive compared to the costs of deploying even a modest SNMP installation, and theyre very easy to configure and use. Although most network polling packages dont address service-level issues, look for more of them to do so in the future. Of course, youll never have the rich level of information that SNMP provides, but you might not need it. In short, a polling package is a one-stop application where you can monitor many services easily. Figure 22.3 shows one of them.
Figure 22.3 Bastas Netoscope just keeps polling away!
Network management can be as expensive as you let it be. Of course, ostensibly, when you install a network management station and configure your network for management, youre trying to save time and avoid downtimeboth of which contribute to your bottom line.
Still, before you go out and plunk down your hard-earned dollar, be sure to go and check references on any expensive network management package. More than that, try to find businesses that operate the way yours does. You can learn from their experience with network management, and you can possibly avoid some expensive mistakesor be told, Cmon in, the waters fine! Either way, youll know what to expect from your network management experience.
Network management can be a slippery phrase; its used to refer to everything but the kitchen sink. In its most helpful form, network management involves network monitoring, which allows you to assess the health of your network.
SNMP (Simple Network Management Protocol) is at the heart of complex solutions; many vendors supply reasonably complete MIBs and agents for their equipment and software, which can then be read by SNMP management stations. SNMP management stations are really good at long-term resource trend monitoring and can help you baseline your network.
SNMP agents can broadcast traps to the network, which are then picked up and acted on by management stations. Typically, notification (such as activating a pager) is the best that most management stations can manage. SNMP traps can be annoying or they can be a blessing, depending on whether theyre waking you up in the middle of the night for a printer jam or to alert you that a public safety system is down.
Generic socket-polling packages for TCP services are also available, and so are service-specific polling packages. The generic packages are limited in that they typically only tell you whether a service is down or up (that is, theyre pass/fail graders). They generally dont report how well the service is doing on resources and response times.
Some of the service-specific and vendor-supplied monitoring utilities, such as the monitoring applications that come with certain servers, switches, and routers, will give you an SNMP-like wealth of information without the overhead that SNMP implies.
Depending on the amount of money youre going to spend on a network monitoring solution, youll want to do some legwork and check references thoroughly before you invest. Although any polling software solution is typically cheap enough to be throw-away if it doesnt meet your needs, a complete SNMP solution is expensive enough in time and money invested that investigating how well it does in a similar shop is a good idea.
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