How to enable cache flow in Cisco ISR 4451 router

[Raja_D]

Hi, 

How to enable cache flow in Cisco ISR 4451 router?? 

I notice that the regular command "iP route-cache flow" cannot be used, instead I find several other commands like iP route-cache same-interface or just iP route-cache and 2 more similar commands which I could not recall. 

However, when I try to enable iP route-cache on Lan and Wan interfaces to identify traffic flow of inward n outward ip's, I don't find it as seen that command on interface level and more over "show ip cache flow" does not show any output. 

Please suggest me as of how this works out in this Cisco ISR 4451 model router.. 

Thanks, 

James... 

[Jon Marshall]

James

https://supportforums.cisco.com/discussion/11997606/netflow-commands-4451

Jon

[Raja_D]

Jon, 

Thank you for sharing the document. 

Does configuring flow cache on a cisco ISR 4451 router consume more CPU utilization or will it result in any performance issues ??

we have cisco ISR 4451 router being used for multiple vendor communication over which we have the VRF lite being used. External vendor's are connected through P2P from this cisco ISR 4451 router.

Please advise as I am trying to enable it to make use of the "cache flow" feature to identify the forward and reverse response for the communication that happens through this router.

James.. 

[Jon Marshall]

James

I haven't used it on an ISR so can't say one way or the other.

As a general answer there is always a performance hit when you enable any feature and obviously you will use more memory to store the records but I doubt it will be a problem unless of course your router is already using a lot of it's resources.

No guarantees though obviously.

Jon

[Joseph W. Doherty]

Like John, Netflow's CPU impact can be difficult to predict.

Netflow, when caching, might reduce the load on a router as it can bypass "routine" processing for a packet.  However, it adds its own additional processing.  So, the balance could tip either way, i.e. more or less CPU depending on what "routine" processing has been bypassed compared to what additional processing Netflow has added.

Further to muddy the waters, different L3 platforms provide different hardware packet processing capabilities.  The same logical configuration, processing the same traffic, may impact the CPU load in different ratios on different platforms.