Troubleshoot network performance issues

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Jul 23rd, 2010
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I am working as network analyst of a Organization with multiple agencies connected Organizations centrally located data center.

One of our agency Public Library having network congestion and performance issue, Noticed that one of the uplink port connected to data centre is over utilized and configured one more port to load balance between two ports. Though it has two links, still we notice the link chock with 90% of utilization for 5 mins rate.

How to trace what is the root cause ? Did sniffer capture and looks like we have valid traffic, we have this over utilization happens daily between 1:00 PM to 5:00 PM EST.

Can you provide some built in cisco commands to trace the source or root cause.



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lingalaccnp Fri, 07/23/2010 - 08:46
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In continuation to that post, please check Rxload and input rate for your information

Library-3725#sh int fastEthernet 0/0

FastEthernet0/0 is up, line protocol is up

  Hardware is Gt96k FE, address is 0007.b35d.0d90 (bia 0007.b35d.0d90)

  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,

     reliability 255/255, txload 10/255, rxload 230/255

  5 minute input rate 90507000 bits/sec, 8501 packets/sec

  5 minute output rate 4249000 bits/sec, 4890 packets/sec

     460770375 packets input, 669768326 bytes

     Received 23689052 broadcasts, 0 runts, 0 giants, 0 throttles

     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

     0 watchdog

     0 input packets with dribble condition detected

     3898047301 packets output, 1622721829 bytes, 0 underruns

     0 output errors, 0 collisions, 3 interface resets

     0 babbles, 0 late collision, 0 deferred

     0 lost carrier, 0 no carrier

     0 output buffer failures, 0 output buffers swapped out


lingalaccnp Fri, 07/23/2010 - 09:21
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cont..., any kind of support will be more helpful...

Public-3725#sh running-config interface fastEthernet 0/0

Building configuration...

Current configuration : 94 bytes


interface FastEthernet0/0

no ip address

ip route-cache flow   (enabled this inorder to capture Rx/Tx flows)

duplex auto

speed auto


Public-3725#sh running-config interface fastEthernet 1/0

Building configuration...

Current configuration : 93 bytes


interface FastEthernet1/0

no ip address

ip route-cache flow        (enabled this inorder to capture Rx/Tx flows)

speed 100



Public-3725#sh int fas

Public-3725#sh int fastEthernet 0/0 | incl rate

  Queueing strategy: fifo

  5 minute input rate 95988000 bits/sec, 9026 packets/sec

  5 minute output rate 4546000 bits/sec, 5412 packets/sec

Public-3725#sh int fastEthernet 1/0 | incl rate

  Queueing strategy: fifo

  5 minute input rate 5735000 bits/sec, 5918 packets/sec

  5 minute output rate 96526000 bits/sec, 9418 packets/sec


-Public-3725#show processes cpu

CPU utilization for five seconds: 62%/62%; one minute: 62%; five minutes: 60%

PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process

vmiller Fri, 07/23/2010 - 13:21
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You need to capture the top talkers during the time frame. Its been a while since i have used a sniffer, but there should be a means to break down who is sending what.


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