Cisco 3750 switch high cpu due to interrupt

Unanswered Question
Ganesh Hariharan Tue, 04/27/2010 - 22:21


We have cisco 3750 switch high cpu due to interrupt and TCAM utilization is full on ASICs because of unicast.

Please guide what is cause interrupt because traffic. If it is traffic how to measure in Mpps in cisco 3750 switch


When the interrupt percentage is high, the root cause of the problem is that the CPU is receiving too many packets. To resolve the problem, you need to find the source of the packets, and either stop the flow, or modify the switch configuration.

Check out the below link for analyzing the network traffic to overcome the interrupt issue.

Hope to Help !!


CSCO11584685 Sat, 05/01/2010 - 00:20

all zero mac? well it doesnt sound logical. so i looked for it.I dont think that should happen often.

Switch Filter All-Zero MAC Addresses from the CAM Table

The switch filter frames with a source MAC address of       00-00-00-00-00-00, which is an invalid source MAC, from the CAM table.  This is       an example of the syslog error output when this occurs:

%SYS-4-P2_WARN: 1/Filtering MAC address 00-00-00-00-00-00 on port 2/48 from host table

These messages are informational and tell you that a frame that has  a       source MAC address of 00-00-00-00-00-00 is found, and the switch will  never add       that to the CAM table. However, the switch will forward traffic  sourced from an       all-zero MAC address.

The workaround is to identify the end station that generates frames       with an all-zero source MAC address. Typically, one of these devices  transmits       such frames:

  • A traffic generator, such as Spirent SmartBits

  • Certain types of servers, such as load-balancing IBM WebSphere           servers

  • A misconfigured router or end station, such as a device that           transmits all-zeros broadcasts

  • A faulty NIC

Ganesh Hariharan Sat, 05/01/2010 - 08:29

Thanks Ganesh.

I have read the document. We captured sniffer of packet but could not find the source of traffic. Is there any command or solution to capture high utilized MAC address.

It is noticed that all zero mac address flooding in the network.


Actually with etheral capture you should able to see the source and destination of the packets, anyway try with command show interfaces statistics detail for fast ethernet details it will help you to find the  Traffic statistics: per ports with input and output packets bps.

and as suggested check out the link for all zero mac-address problem.

Hope to Help !!


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