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For Information about performance management in the latest version please refer to:

opFlow 3 Scalability Features  

Flow Volume - sent from Cisco Device

Cisco devices will tell you the number of flows currently exported, no matter if they were successfully received by a server or not. This can be very useful to help calculate the amount of flow data that will come from a device before sending the flows to an opFlow server.

1. Get the current time
2. Get the number of flows
3. Wait X minutes, for example 2 or 60
4. Get the current time
5. Get the number of flows
6. Do some math, subtract second flow number from first flow number, that is the number of flows for X minutes, divide by X * 60 (so the number of seconds) and you have the number per second.  Doing this over more time will give you a better idea of the overall number, it is suggested that you wait much more than 2 minutes

router> show clock
11:57:51.155 AEST Wed Apr 2 2014

router>sh ip flow export 
Flow export v9 is enabled for main cache
  Export source and destination details : 
  VRF ID : Default
    Destination(1)  192.168.1.7 (12345) 
    Destination(2)  192.168.1.42 (12345) 
  Version 9 flow records
  25716317 flows exported in 890127 udp datagrams
  0 flows failed due to lack of export packet
  0 export packets were sent up to process level
  0 export packets were dropped due to no fib
  1 export packets were dropped due to adjacency issues
  0 export packets were dropped due to fragmentation failures
  0 export packets were dropped due to encapsulation fixup failures

So 25716317 have been sent.  Now wait 2 minutes, then get the time again

router>show clock
11:59:53.155 AEST Wed Apr 2 2014

Now get the number of flows again:

meatball>sh ip flow export 
Flow export v9 is enabled for main cache
  Export source and destination details : 
  VRF ID : Default
    Destination(1)  192.168.1.7 (12345) 
    Destination(2)  192.168.1.42 (12345) 
  Version 9 flow records
  25717645 flows exported in 890173 udp datagrams
  0 flows failed due to lack of export packet
  0 export packets were sent up to process level
  0 export packets were dropped due to no fib
  1 export packets were dropped due to adjacency issues
  0 export packets were dropped due to fragmentation failures
  0 export packets were dropped due to encapsulation fixup failures

Our clock difference was almost exactly 2 minutes, so we will use that number in the example for our calculations.

To figure out flows / 2 min  or flows / second:

25717645 flows - 25716317 flows = 1328 flows / 2 min

1328 / 120 = 11 flows / second

The numbers you see will likely be higher, this is just an example.  Please contact support@opmantek.com if you would like help correctly sizing your server.

Flow Volume - received by opFlow

opflow_stats.pl calculates how many flows per second are being received by the server.  To view this info just run it

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