Cisco – How to know the interface utilization on a Cisco switch

bandwidthciscocisco-commandsinterfaceswitch

I would like to confirm. Is the above below information in bold sufficient to know the utilization of my interface in percentage?

Switch#sho int fa0/8  
FastEthernet0/8 is up, line protocol is up (connected)  
  Hardware is Fast Ethernet, address is 001c.b1b8.1808 (bia 001c.b1b8.1808)  
  Description: connected to RICI_1E1  
  MTU 1500 bytes, BW 2048 Kbit, DLY 100 usec,  
     reliability 255/255, txload 23/255, rxload 22/255  
  Encapsulation ARPA, loopback not set  
  Keepalive set (10 sec)  
  Full-duplex, 100Mb/s, media type is 10/100BaseTX  
  input flow-control is off, output flow-control is unsupported  
  ARP type: ARPA, ARP Timeout 04:00:00  
  Last input 00:00:00, output 00:00:00, output hang never  
  Last clearing of "show interface" counters never  
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0  
  Queueing strategy: fifo  
  Output queue: 0/0 (size/max)  
  5 minute input rate 12329000 bits/sec, 1707 packets/sec  
  5 minute output rate 2933000 bits/sec, 1331 packets/sec  
     6694535692 packets input, 5277030343947 bytes, 0 no buffer  
     Received 1079534037 broadcasts (145728815 multicasts)  
     0 runts, 0 giants, 0 throttles  
     83072 input errors, 83072 CRC, 0 frame, 0 overrun, 0 ignored  
     0 watchdog, 145728815 multicast, 0 pause input  
     0 input packets with dribble condition detected  
     4448677146 packets output, 1162660273701 bytes, 0 underruns  
     0 output errors, 0 collisions, 1 interface resets  
     0 babbles, 0 late collision, 0 deferred  
     0 lost carrier, 0 no carrier, 0 PAUSE output  
     0 output buffer failures, 0 output buffers swapped out  
Switch#

Utilization in = (inputRate/BW)*100
Utilization Out = (inputRate/BW)*100

Best Answer

What you are looking at is the bit rate over the last five minutes. You can change the time period, but not below 30 seconds with the load-interval command.

I'm not sure what you mean by "utilization." It looks like you are wanting a percentage, but the percentage you come up with will be over the specific time period. If you get 40%, your interface could have been at 100% for two out of the five minutes, and completely idle for three minutes.

Edit:

I think I see where you are going wrong. It looks like someone used the bandwidth command on the interface, and that is showing up in your show interfaces output. That command doesn't really change the bandwidth on the interface; it is something which allows features, e.g. QoS, to use that as the basis for calculations, but the actual interface bandwidth isn't affected.

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