Cisco IOS IP SLA Traffic Generator

Hello Gowtham

The command on R1 that initiates the data streams is this one:

ip sla schedule 1 life forever start-time now

This begins the generation of the traffic. This is due to the “udp-jitter” command. This command is used to measure jitter, and to do so, a steady stream of traffic must be sent. So with this config in R1, you can generate traffic, but you must initiate it using the above command, with the appropriate IP SLA number. The above initiates IP SLA 1.

Now, in order to match traffic on the other end, you must create the appropriate policy maps to count the packets received. Now if you’re not seeing any traffic being matched, then something is wrong with some configuration on either router. I suggest you check the following:

  1. Do a packet capture to ensure that traffic is indeed being sent from R1 to R2.
  2. Ensure that you are matching the correct protocol (UDP), the correct IP address, and the correct UDP port number.
  3. Also, make sure that the policy map has been attached to the appropriate interface and is applied using “input” which indicates an inbound direction.
  4. Keep in mind that by default, the interface statistics are updated every 60 seconds, so if you check stats in less than 60 seconds, you will still see zero traffic. You can change the update interval as done in the lesson to a smaller value, to speed up the appearance of stats.

Hopefully those pointers will help you to move in the right direction in your troubleshooting process. Let us know how you get along.

I hope this has been helpful!

Laz

Hi Laz,
Now I can see the traffic hitting the router R2. Issue is in access-list. In R1 IP Sla config, udp-jitter port number referred is source port. It was not matching ACL which is configured to match destination port.

Thanks,

Hello Gowtham

Ah, I see. The port number indicated in the udp-jitter command on R1 is indeed that of the destination, and should match the destination port number in the ACL configured on R2.

I hope this has been helpful!

Laz