I had an odd issue that consumed my entire afternoon today. We deployed a couple of VM’s into a private VLAN using VMM 2008. The network admin did his usual stand up job and passed me on details to network the servers. I configured the first and it couldn’t access the network.
We suspected networking because in my experience “if it isn’t DNS then it’s the network”. It could have been something simple with the VLAN configuration or firewall rules. The network admin came back and said everything checked out in Cisco world so it must be the blade enclosure. I really doubted it. I take care of the blades but the network admin has bad memories of virtual connects, trunk links and shared uplinks. I double checked everything and it was fine.
Time to troubleshoot. By now the second VM was networked and having the same issue. Neither VM could ping each other. I moved one onto another VLAN and it worked fine. OK – the virtual connects must be OK. I moved the other VM onto another cluster and suddenly it worked OK on the new VLAN. Hmm – that ruled out the blades and the Cisco network leaving the host. However, I knew that the hardware was fine because the other VM’s on that external virtual network (physical NIC) were fine.
I decided to change the external virtual that the VM was bound to. I’ve left my two physical NIC’s for VM’s unteamed (no s/w installed yet) until I had a supported solution from HP. So, I have Virtual Network 1 and Virtual Network 2 configured for the two NIC’s. I changed the VM from VN1 to VN2 and suddenly it worked. I moved it back to VN1 to diagnose.
OK – so is it the virtual network? Nope, because all the other VLAN’s and VM’s on it work OK. So this brings it down to the VM. The integration components were installed by VMM. The VM was created by VMM. I powered it down and recreated the NIC. No fix.
I went directly to the Hyper-V console. It’s clear here that a VMM created synthetic network adapter has some difference to a Hyper-V created synthetic network adapter because they have different names. I removed the VMM created NIC and used the Hyper-V MMC to replace it. I booted up the VM and it worked.
AHA! For some reason, VMM is creating non-functional synthetic NIC’s on my Hyper-V hosts. I’ll have to contact MS about this one.