The following network checklist can be used to determine a network’s health status:
■ New segments should use switched and not use dated hub/shared technology.
■ 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 com-
monly, 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 regis-
tered 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 more than 75 percent for a 5-minute interval likely suggests net-
work 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.
ptg
Chapter 1: Network Design Methodology 23
■ QoS should be enabled on network devices to allow for prioritization of time-sensi-
tive or bandwidth-sensitive applications.
Источник: Bruno A., Jordan S. - CCDA 640-864 Official Cisco Cert Guide - 2011, 4th Edition
■ New segments should use switched and not use dated hub/shared technology.
■ 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 com-
monly, 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 regis-
tered 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 more than 75 percent for a 5-minute interval likely suggests net-
work 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.
ptg
Chapter 1: Network Design Methodology 23
■ QoS should be enabled on network devices to allow for prioritization of time-sensi-
tive or bandwidth-sensitive applications.
Источник: Bruno A., Jordan S. - CCDA 640-864 Official Cisco Cert Guide - 2011, 4th Edition
