We have 7 ESXi hosts (5.5 Update 1 - build 5.5.0,1623387) in cluster. Each is running on a Dell PowerEdge R720 server and each is configured identically. We purchased add on NICs (Broadcom Corp NetExtreme II BCM 57810 10 Gigabit Ethernet) for each server about a year ago. There were 2 of these in each host and they were working without incident. About a month ago we had 2 redundant Cisco Nexus switches installed in this rack and only the Broadcom BMC 57810 cards are connected to these. Ever since then we get randomized alerts from vCenter that say "Network Redundancy Degraded" emails and it shows a port on one of the NICs is down. It is always one of the ports on one of these Broadcom NICs. We get about 5-8 of these alerts every day, random times, ESXi server, NIC and port. I was thinking it was a driver issues and I did see this article (below) but I cannot find the driver version 1.78.80.v55.4 for ESXi 5.5 Update 1. If I look on the support matrix is only shows driver version 1.78.80.v55.3. Does anyone know where I can get the driver version 1.78.80.v55.4 or have any other suggestions?
We too use the same Network adapters but with the R620/R630s there are a few things i would recommend that we found resolved the same / similar issues for us:
1. Check that all firmware is up to date on the server (specifically the broadcom firmware) a useful tool for this is Dell Repository Manager
2. Did you use the Dell Media to build the ESXi Hosts? the reason i ask is they include specific more reliable drivers, you can get these from the dell support site under ESXi OS. If you havent used this media, you can add it as an upgrade to Update Manager and then upgrade your hosts to it. it will do an upgrade and install the drivers etc required.
3. Do you have dropped packets when pinging the management IP Address? if so i would recommend adding a new temporary management interface, removing the default one and adding it back again, then remove the temporary interface, the reason for this is that VMware VMK0 uses the same mac as the first interface which can cause mac flaps on the switches.
Hopefully this will help you.