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Network Failure Between Guest and Physical Network
Details
Why does my guest network hang when I try to FTP a file to a remote server or access network shares in the virtual machine from a remote client?
Solution
The VMware network bridge may drop large packets in situations in which the host's network adapter has an MTU (Maximum Transmission Unit) smaller than the MTU in the guest operating system. The virtual network interface driver in the guest operating system is unaware that the host is unable to transmit its packets.
This problem occurs only with bridged networks. Host-only and NAT networks are not affected.
To work around this problem, you can configure a smaller MTU in the guest operating system's TCP/IP stack. In Linux guests, you can set the MTU with the ifconfig utility. In Windows guests, you can set the MTU by modifying the registry, or you may be able to find a utility on the Web to change network configuration.
The guest's MTU must be no larger than the MTU of the host physical adapter to which the virtual machine is bridged. If you have more than one physical network adapter on the host, and the virtual machine is configured to select host adapters automatically (the default configuration), you need to use the lowest MTU of all your host adapters.
To view the MTUs for all active network adapters on a Linux host, use ifconfig. To find MTUs on Windows hosts, you need to look in the Windows registry. The exact location depends on which host operating system you are running. Consult the Microsoft Knowledge Base at www.microsoft.com. For example, you may find instructions for Windows 2000 or Windows NT at support.microsoft.com/default.aspx?scid=kb;EN-US;Q120642 .
To change the MTU in a Linux guest, use a command like this at a terminal prompt:
Alternatively, you could enable both EnablePMTUDiscovery and EnablePMTUBHDetect in the Windows registry to allow the guest to adjust packet size downward if the guest receives no replies when a packet is silently dropped. This workaround doesn't require knowledge of the host's MTU, but may decrease performance for large transfers.
For a related solution, search on "Win XP VMs can't connect to network" in the Workstation discussion forum at www.vmware.com/community.
