Network lost on RHEL guest on Hyper-V after switching to synthetic vNIC

Solution Verified - Updated -


A fresh RHEL 5.9-beta installation with the hv drivers results in a functioning VM. Afterwards we want to upgrade the vNIC from a low-performing emulated card to a synthetic vNIC. However, RHEL 5.9 Beta does not recognize this card, and the machine comes up without network.

We noticed that the network script /etc/sysconfig/network-scripts/ifcfg-eth0 is renamed to /etc/sysconfig/network-scripts/ifcfg-eth0.bak in the first boot after vNIC upgrade, but no new /etc/sysconfig/network-scripts/ifcfg-eth0 is created. This is perhaps not so surprising, as lspci does not report a network card any longer.


  • Red Hat Enterprise Linux (RHEL) 5.9 Beta guest, hv_netvsc driver
  • Microsoft Windows 2008 R2 SP1 Hyper-V virtualisation hypervisor
  • Hyper-V configuration changed from emulated NIC to synthetic vNIC

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