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High CPU Utilization in cisco switch 2900XL-Urgent

We have few switches of 2900XL series in production.CPU utilization is above 90% in 2-3 switches which is causing a very slow network traffic and high round trip time.From "sh process cpu" I am able to see that 60-70 % CPU is utilized by 'virtual exec proc'.Even I tried to clear the unnecessary telnet sessions with the help of "clear tcp tcb..." but there is no improvement.Please suggest for the same since it is very critical.

5 REPLIES
Bronze

Re: High CPU Utilization in cisco switch 2900XL-Urgent

This doc might help:

High CPU Utilization in Exec and Virtual Exec Processes

http://www.cisco.com/en/US/products/hw/routers/ps359/products_tech_note09186a00801c2ae4.shtml

New Member

Re: High CPU Utilization in cisco switch 2900XL-Urgent

Hi,

Thanx for prompt response.But as I have mentioned in the problem description I have already tried these things which are included in above link(clear tcp tcb...etc).Please do advise.

New Member

Re: High CPU Utilization in cisco switch 2900XL-Urgent

Maybe a host is doing a DoS attack.

Do you have hosts on the administrative VLAN of the swtichs?

I you do not have a firewall between your hosts, you can filter source IP address for telnet connections.

http://www.informit.com/library/content.aspx?b=CCNP_Studies_Troubleshooting&seqNum=81

Example 7-58 illustrates the access list configuration to only allow hosta to telnet to r3.

Example 7-58. ACL Configuration

r3(config)#access-list ?

<1-99> IP standard access list

<100-199> IP extended access list

<1000-1099> IPX SAP access list

<1100-1199> Extended 48-bit MAC address access list

<1200-1299> IPX summary address access list

<1300-1999> IP standard access list (expanded range)

<200-299> Protocol type-code access list

<2000-2699> IP extended access list (expanded range)

<300-399> DECnet access list

<400-499> XNS standard access list

<500-599> XNS extended access list

<600-699> Appletalk access list

<700-799> 48-bit MAC address access list

<800-899> IPX standard access list

<900-999> IPX extended access list

rate-limit Simple rate-limit specific access list

r3(config)#access-list 1 ?

deny Specify packets to reject

permit Specify packets to forward

r3(config)#access-list 1 permit ?

Hostname or A.B.C.D Address to match

any Any source host

host A single host address

r3(config)#access-list 1 permit 192.168.5.17

r3(config)#access-list 1 deny any log

r3(config)#line vty 0 4

r3(config-line)#access-class 1 ?

in Filter incoming connections

out Filter outgoing connections

r3(config-line)#access-class 1 in

r3(config-line)#end

r3#copy running-config startup-config

Now test out the ACL as in Example 7-59.

Example 7-59. ACL Testing

sw3512xl#telnet 192.168.5.30

Trying 192.168.5.30 ...

% Connection refused by remote host

sw3512xl#ping 192.168.5.30

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 192.168.5.30, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/3 ms


Guido.

Please rate all the helpful comments.

New Member

Re: High CPU Utilization in cisco switch 2900XL-Urgent

How's your current network topology ?

Where are these L2 devices attached? I suspect you would have either an Router or MLS?

Does this happen all the time or some time during the day ?

Regards,

Hall of Fame Super Gold

Re: High CPU Utilization in cisco switch 2900XL-Urgent

Put a link utilization. It may sound that you have a broadcast storm.

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