2

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

  • You can also look at txload and rxload (they are 255 based, i.e. 8-bit) – Ricky Beam May 19 '16 at 19:47
  • oss.oetiker.ch/mrtg – Ron Royston May 19 '16 at 19:58
  • To convert txload and rxloads to percentages, divide the first figure by 255 and then multiply the result by 100. For example, txload 23/255 = 9% utilised. – OzNetNerd May 20 '16 at 4:05
  • @RonRoyston, Please your reply didn't help as I wish to know hwhere and how to get the information used by MRTG to get the information is displays – NTD May 20 '16 at 7:15
  • Please, in the comments below the answer below, @RonMaupin said That is a 100 Mbps interface and your input rate is only 12 Mbps, and the output rate is only 3 Mbps. Your calculation gives 12.329% for the input and 2.933% for the output. What makes the difference between your method and he's – NTD May 20 '16 at 7:21
4

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.

  • Thanks for your reply. From my calculations, I great a utilisation greater than 100% Is it normal? – NTD May 19 '16 at 16:59
  • 1
    I don't see that happening there. That is a 100 Mbps interface and your input rate is only 12 Mbps, and the output rate is only 3 Mbps. You are doing something wrong in your calculation. Your calculation gives 12.329% for the input and 2.933% for the output. – Ron Maupin May 19 '16 at 17:02
  • Thanks for your reply @Ron. In my calculation, I used the 2048kbits( figure just after the BW in my show int output, which I understand is the bandwidth of my interfaces). Why use 100Mbps (which I suppose is the figure after the full duplex in my show int output) and not 2048kbits – NTD May 20 '16 at 7:11
  • Hello @Ron. I just noticed the edit in your question. In the case where that is used, can I use my calculation which yields a ustilization greater than 100% above? – NTD May 20 '16 at 7:38
  • 1
    Using that yields incorrect results. A FastEthernet interface, connected to a FastEthernet interface, will transfer bits at 100 Mbps, except when the speed is set to 10 Mbps with the speed command or by negotiation with an Ethernet port. The bandwidth command is purely for things like routing protocols and QoS. Instead of the BW 2048 Kbit on the third line, look at the 100Mb/s on the seventh line: Full-duplex, 100Mb/s, media type is 10/100BaseTX. That will give you the connection speed. – Ron Maupin May 20 '16 at 13:28

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