Understanding the network.pdf - Back to Home

and low utilization measurements vary from network to network, depending on
traffic flow patterns, applications, and number of users.
In regards, to the "normal" average network utilization measurement values,
industry-standard utilization averages can be used as baselines for comparison.
With the understanding that your network's utilization should fall in close relation to
the baseline average to ensure optimum performance. For example, on a shared
802.3 Ethernet segment, the average utilization should be around 30 percent of the
available bandwidth, with 55 percent being the maximum peak bandwidth
utilization rate and a 1 percent collision rate. On an 802.5 Token Ring, the average
utilization is 40 percent, with a peak of 65 percent. Table 11.1 provides some
baseline average and peak utilization guidelines for Ethernet, Token Ring, and
FDDI.
Table 11.1. The LAN Protocol Utilization Baseline Measurement
Guidelines
Transmission Medium Transmission Speed Average
Utilization
Peak
Utilization
Shared Ethernet 10Mbps
100Mbps
and 30 percent 80 percent
Switched Ethernet Half-Duplex 80 percent 90 percent
Switched Ethernet (including Full-Duplex 97 percent
Gigabit Ethernet)
[†] 97
percent [†]
Token Ring 4/16Mbps 40 percent 65 percent
Switched Token Ring Half-Duplex 80 percent 90 percent
Switched Token Ring Full-Duplex 97 percent [†] 97
percent [†]
FDDI 100Mbps 60 percent 90 percent
[†] In the case of full-duplex transmission links, the bandwidth utilization rate is the same for both the transmit
and receive pairs.
Now, if your network's average utilization rates are on the high side (5 to 15 percent
over the average). This does not necessarily mean that you have a problem. Rather,
additional sampling and analysis should be done to determine if these rates
represent a real performance problem or just the natural operational rate of your
users and their applications. You see the baselines, while accurate are skewed
towards the worst case operational scenario, rather then "normal" operational
conditions. Particularly in the case of Ethernet, which of all the LAN transmission