Understanding the Health of Network
Devices
The next step in
understanding the network's impact on application performance is to know the
limits of your network. Every router, switch, network card, and cable has a
capacity limit. If the limiting factor is not the speed of the interface, it
could be the CPU or memory utilization of each device that the traffic must
traverse.
A router or switch that is running at
capacity may drop an excessive number of packets (that is, become a point of
congestion). If aggregation and oversubscription are not planned appropriately,
packet loss and queuing delays could have a significantly adverse effect on the
performance of applications traversing that device.
Network switches are commonly
designed with inherent oversubscription. For instance, a switch that supports 24
ports of 1000-Mbps traffic per port may not have an adequate backplane capacity
to support 24 ports under full load. Understanding the limits of a router,
switch, firewall, or other network element will help identify potential
bottlenecks in the network. Adequately sizing network infrastructure components
will help prevent network stability issues and better guarantee higher levels of
application performance.
Several monitoring utilities exist today
that allow you to monitor all aspects of a router or switch. Monitoring
utilities range from simple shareware tools to monitoring and reporting systems
that cost millions of dollars. The following sections describe SNMP-compliant
managers and syslog.
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