I upgraded my XenServer from 5.6 to 5.6 FP1 and lost network connectivity.

I’m not the only one having problems…

Packet loss on XenServer 5.6 Feature Pack1

I compiled the latest Realtek driver with the XenServer 5.6 FP1 DDK and installed the driver on my 5.6 FP1 machine… no dice. I keep getting the following error: “bringing up management interface xenbr0: cannot set large receive offload settings: Operation not supported“.

The release notes mentioned the following regarding lro and gro:
By default, Large Receive Offload (LRO) and Generic Receive Offload (GRO) are disabled on all physical network interfaces. You can enable them by setting the PIF object other-config parameter values to ethtool-lro or ethtool-gro to true, though this can affect guest network performance adversely. [CA-46342]

I’m restoring 5.6. I’ll upgrade when/if Citrix posts a fix.