Ok there have been a lot of threads about trying to get the Dell R720 working with the Broadcom 5720 daughter card. You can inject the drivers post build or you use the DELL recovery cd http://ftp.dell.com/FOLDER00609866M/1/ to build the server.
The problem I am highlighting in this post occurs when the servers are commissioned. We put 4 DELL R720 servers in production. They are configured using 4 ports on the 5720 etherchannelled and using vDs. Within 2-3 weeks at different times all 4 hosts experienced a network failure and caused production outages. All Vm's were unresponsive & offline and a reboot of each physical host resolved the issues temporarily but would reoccur at a later date. Calls to both vmware and Dell were not very productive and it took 2 months to finally work out the problem, involving a lot of time & effort on my part. Basically specific to the DELL R720 server the below criteria must be enforced to ensure the hosts do not experience random network loss.
- DELL R720 must be at least BIOS version 1.2.6
- vSphere Build must be as least ESXi 5.0 Update 1
- The Interuppt Remapping must be disabled via SSH on the host - see vmware kb below
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1030265
The above was implemented on all 4 hosts they have been stable for the last 8 weeks.