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Effects of SPAN port configuration on Cisco 4507R+E switch.

Sundeep Dsouza

Hi All,

I read quite a few documents on configuring SPAN on a cisco switch but none of them mention any limitations or any kind of CPU load it can have on a switch. I need to configure this on one of our switches and would like to know if there are any implications related to SPAN.


5 Replies 5

Reza Sharifi
Hall of Fame Expert Hall of Fame Expert
Hall of Fame Expert


If you are running IOS 12.2(19) or later release, you can monitor the CPU to see if there is any impact when SPAN is turned on.

Have a look at this doc:


Hi Reza,

I actually do not want to reach to that stage where after turning on SPAN I run into CPU issues hence I wanted to know if there are any issues with SPAN.

I have used SPAN earlier in production networks but the network where I configured SPAN was not huge enough. The current network has lots of VLAN and traffic passing across so I am kinda skeptical.


Frequent Contributor
Frequent Contributor

From my own experience I've tried span on a 4500 and 6500 for a complete VLANs and it was fine I even have IPSs running in promiscuous mode witch requires SPAN and it's working fine.

so, have no fear


Posted by WebUser Ahmed Rasmy

I'm asking myself the same question, how SPAN can load the CPU, in particular if you monitor more 10G port on a 4500. Do you have a feedback about issue above ?

Your best bet would be to turn span on and keep a close eye on your CPU levels.

Sent from Cisco Technical Support iPad App

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