So quick troubleshooting ... we have to find where is the difference
Let's go step by step ...
- NIC ports on ESX vSwitch in BLADE1 are configured to use auto negotiation so no problem here
- Ports on Force 10 IOA are also configured for auto negotiation and configuration is consistent across all ports in switch modules so that's not a problem.
- ESX builds are the same on both blade servers.
- What are NIC firmwares? On BLADE1 there is 7.2.14 and on BLADE2 7.6.15
Bingo!!! Let's upgrade NIC firmwares on BLADE1 and check if this was the root cause of the problem ...