Unknown Unicast Flooding - Part 2

In the first UUF entry, geertn444 reminded me of a nagging question:  Does making the ARP timeout equal to the CAM timeout cause very short UUF problems?  I tested this with two 6500s and a traffic generator.  Setting two timers equal to each other did not cause flooding problems.  I ran the test sequence between 10 and 15 times.

For those of you already using 300 seconds as your ARP timeout, which was the default CAM timer, and have since upgraded to SXI, you now have a large safety cushion because the default CAM timer has been increased to 480 seconds.


  1. Do you use any special hardware for traffic generation? I would like to stress some Cisco equipment but not sure how to do it properly

  2. I use an appliance specifically designed for traffic blasting and analysis. Spirent, Ixia, and BreakingPoint are the 3 most popular manufacturers, I use a Spirent. These devices are very expensive, but you can often rent them.

    At customers where I don't have access to this equipment, but need to run very basic tests on smaller circuits, like T-1s and microwave, I use iPerf ... that's free.