We were installing a brand new Cisco UCS chassis with a customer and had to use 1GbE uplinks from each fabric extender. We started getting some strange ping issues where ping would work about 60-90% of the time. As we tried to figure it out, we checked each component and were pretty satisfied that our service profile was correct. Then we started checking the network and lo and behold we realized that two of our servers had the MAC addresses! After removing the duplicate all worked great.
Lesson learned: When creating your own mac addresses be sure they are unique! Better to put everything in one or more unique pools and just select from the pools instead of creating them one at a time.
