Network Checklist
The following is a network checklist that can be used to determine a network’s health status:
■ No shared Ethernet segments are saturated (no more than 40 percent sustained network
utilization). New segments should use switched and not shared technology.
Designing the Network Topology and Solutions 21
■ No WAN links are saturated (no more than 70 percent sustained network utilization).
■ The response time is generally less than 100ms (one-tenth of a second). More commonly less
than 2ms in a LAN.
■ No segments have more than 20 percent broadcasts or multicast traffic. Broadcasts are sent to
all hosts in a network and should be limited. Multicast traffic is sent to a group of hosts but
should also be controlled and limited to only those hosts registered to receive it.
■ No segments have more than one cyclic redundancy check (CRC) error per million bytes of
data.
■ On the Ethernet segments, less than 0.1 percent of the packets result in collisions.
■ A CPU utilization at or over 75 percent for a 5-minute interval likely suggests network
problems. Normal CPU utilization should be much lower during normal periods.
■ The number of output queue drops has not exceeded 100 in an hour on any Cisco router.
■ The number of input queue drops has not exceeded 50 in an hour on any Cisco router.
■ The number of buffer misses has not exceeded 25 in an hour on any Cisco router.
■ The number of ignored packets has not exceeded 10 in an hour on any interface on a Cisco
router.