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Beginner

Port Mirror

Hi,

I am having one Cisco 3850 switch and i want to know about SPAN.

 

monitor session 1 destinationinterface Te1/0/1

monitor session 1 source interfaceTe1/0/2

monitor session 1 source interface Te1/0/3

.

.

?

My question is , what is the max limit to put interface in source?

Also if i keep around 10 interface as a source then any impact on CPU utilization of the switch?

2 ACCEPTED SOLUTIONS

Accepted Solutions
Highlighted

Re: Port Mirror

Hi

 

All is documented here :

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3850/software/release/3se/network_management/configuration_guide/b_nm_3se_3850_cg/b_nm_3se_3850_cg_chapter_0111.html

 

No impact is generaly expected but if you redirect a lot of source interfaces to the same SPAN destination thant it will be a bottleneck and you will loose packets.

 

Regards

VIP Advisor

Re: Port Mirror

Hello

You can have multiple source span ports and mirroring can cause network disruption depending how much traffic you’re mirroring - I am not saying it will cause you disruption but the potential is there for it to do so.

 

I would suggest when you enable your span session that keep an eye on the cpu/memory utilization of the switch, if applicable take a pre/post baseline check.

 

 

 



kind regards
Paul

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future
3 REPLIES 3
Highlighted

Re: Port Mirror

Hi

 

All is documented here :

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3850/software/release/3se/network_management/configuration_guide/b_nm_3se_3850_cg/b_nm_3se_3850_cg_chapter_0111.html

 

No impact is generaly expected but if you redirect a lot of source interfaces to the same SPAN destination thant it will be a bottleneck and you will loose packets.

 

Regards

Beginner

Re: Port Mirror

Thanks Jerome,Paul

VIP Advisor

Re: Port Mirror

Hello

You can have multiple source span ports and mirroring can cause network disruption depending how much traffic you’re mirroring - I am not saying it will cause you disruption but the potential is there for it to do so.

 

I would suggest when you enable your span session that keep an eye on the cpu/memory utilization of the switch, if applicable take a pre/post baseline check.

 

 

 



kind regards
Paul

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future
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