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High Switch Port utilization

gorkal_rajendra
Level 1
Level 1

I have switch-A 3524, fa0/9 is connected to switch-B 2924 fa 0/22. We are observing the output utilization on switch-A fa 0/9 is very high(98.94) and at switch-B 2924 fa 0/22 Input utilization is high(99.06) and there is no other port on switch-B with not more than 10% utilization.

3524, fa 0/9 ----> 2954 fa 0/22

Switch-A interface:-

FastEthernet0/9 is up, line protocol is up

< Deleted >

reliability 255/255, txload 219/255, rxload 14/255

< Deleted>

1005 input errors, 1005 CRC, 0 frame, 1134 overrun, 1134 ignored

0 watchdog, 75042 multicast

I appreciate if some one can help me to find what could be the reason.

1 Accepted Solution

Accepted Solutions

glen.grant
VIP Alumni
VIP Alumni

Those are really old switches so the best way to look at those ports would be to use "sh controllers ethernet-controller fastethernet x/x " to get a good look at all the stats. If you don't have a way to look at the layer 3 info via netflow or other tools then you may have use a packet analyzer and span those ports to get a look at the traffic. To clear the ethernet controller stats it is "clear controllers ethernet-controller " .

View solution in original post

3 Replies 3

Giuseppe Larosa
Hall of Fame
Hall of Fame

Hello Gorkal,

the link fa0/9 is the uplink for the second switch switch-B this should explain why you see an high usage of this port: all packets for users connected to switch-B have to be sent out Switch-A:f0/9.

You say there is no other port on SwitchB with more then 10% usage: these are user ports.

Suppose there are ten users each at 10% : a 90% of FE is needed to go on SwitchA:f0/9 to provide the packets to the users.

If you want to find out the associated traffic for each user you can:

on the router / multilayer switch that provides a default gateway to users configure

int fas0/0

ip accounting output

you can then look at statistics with sh ip accounting on the router.

If you find one user with a lot of conversations with internet for example and high traffic volume that means the PC is running some peer-to-peer software.

If all the traffic is legimitate you are facing a limitation of the current setup: you should consider to create an etherchannel link of 2 or 4 FE between the two switches in order to provider more inter-switch bandwidth.

In the mid / long term you could think to change the switches using newer ones with Gigabit uplinks

Hope to help

Giuseppe

darren-carr
Level 2
Level 2

Hi,

How do you have the speed and duplex of the interfaces in question configured?

Is the inter-switch connection defined as a trunk?

Can you do a 'sh run int fa 0/9' and 'sh run int fa 0/22' on the other switch and post this?

Thanks

glen.grant
VIP Alumni
VIP Alumni

Those are really old switches so the best way to look at those ports would be to use "sh controllers ethernet-controller fastethernet x/x " to get a good look at all the stats. If you don't have a way to look at the layer 3 info via netflow or other tools then you may have use a packet analyzer and span those ports to get a look at the traffic. To clear the ethernet controller stats it is "clear controllers ethernet-controller " .

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