Cisco provides us with a nice starting point for analyzing the health of our existing network as we Plan for redesigns. Check it out:

• Ethernet segments should not feature a sustained utilization of 40% or higher
• All Ethernet segments should be switched – no shared segments (hub-based)
• No WAN links should feature a sustained utilization of 70% or higher
• Response times should be generally less than 100 ms
• LAN response times should generally be 2 ms
• No segments should have more than one CRC (cyclic redundancy check) error per million bytes of data
• No segments should have more than 20 percent multicast or broadcast traffic
• For Ethernet segments, there should be less than .1 percent collisions over 5 minute intervals
• CPU utilization should not exceed 75%
• The number of output queue drops should not exceed 100 in an hour
• The number of input queue drops should not exceed 50 in an hour
• The number of buffer misses should not exceed 25 in an hour
• The number of ignored packets should not exceed 10 in an hour