NAM - Understand bits percentage

cisco_lite · ‎03-28-2009

On the NAM GUI Interface, on Monitor -> Switch -> Port Stats, I see 'Bits/s' column against the ports. Bits/s includes the actual bits per second and a percentage value. The port is gigabit, but it still shows 49% when 217 Mbits is the actual traffic. The 49% relates to which value.

Secondly, even though 217Mbits is bits/s the utilization is shown as 11.58%. Shouldn't it be 20%.

htarra · ‎04-02-2009

believe the utilization number is correct. The customer should also take into account the packet/sec which also affects the utilization (link overhead). The formula NAM use for the utilization is

Bytes (delta) : B

Packets (delta): P

Port speed : S

Time interval : T

Utilization (percent) = 100 * ( 8B + 20P) /ST

Utilization (percent) = 100 * ((8 * bytes/sec) + (20 * packets/sec)) / port speed