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Cisco 4500

What are the most possible cause that would hang out a switch like Cisco 4506 . Anyone can help ?

Cisco Employee

Re: Cisco 4500

Hi Jason,

A high CPU usage continuing for long time can cause switch to hang. Can you confirm which sup you are running in your chassis, which image in running on your sup.

Also is there any crashes,error messages in logs? When you say it is hung you are not able to access the switch via console I believe?



Re: Cisco 4500

spanning tree loops seems to be the most obvious reason for the high CPU load on the switch.


New Member

Re: Cisco 4500

Hi Ankur,

(1)I am running sup IV, the IOS is Cisco IOS Software, Catalyst 4000 L3 Switch Software (cat4000-I9S-M), Version 12.2(25)EWA1, RELEASE SOFTWARE (fc1)

(2)Yes, when it hung, i was not able to access the 4506 through console and was forced to revert to power it off and on.

(3)When system start up, show log does not show any Error accept some bootup interface change message.

(4)I will check whether i can use show command to capture any crash info. But even that, I would not know how to interpret the crash log.

(5) I am running rspt+. I have a second cisco 4506 w/Sup IV running as standby. But the 2nd 4506 did not take over when 1st 4506 hung. The links of all of my edge switches connected to the 2nd cisco 4506 did not change to forwarding, the HSRP does not fail over to 2nd 4506! Is seem like the 1st 4506 still detect that 2nd 4506 is alive. It seem like both RSTP+ and HSRP fails to work ?

(5) What Should I do next ? How can I trouble shoot ?

thks and Regards

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