bridge mode drops connectivity with xp/win2k to xp/win2k vers 2.x-3.1

[rocket888]

Summary: Bridge mode loses connectivty on reads by guest from host. Multiple windows hosts/guest - with linux host, no problem.

This is a problem I've seen for years and there are discussions going back years with no resolution. I've had it with win2000 host and win2000 or xp guests (pro versions in each case, multiple sp's for xp). Under win2000 with win2000 guests, it seemed to happen less. Now, with xp host and xp guest it is repeatable with any file over a few megs in size. This means it's been a problem since at least version 2.x up to 3.1.3.

The problem is repeatable by trying to copy a file (in windows explorer) from a file share on the host.The error is reported as

“cannot copy : The specified network name is no longer available”

Here are a number of data points I've gathered:

1. I can get a similar error using another file copy program. In each case there is a longish (20-30 second) delay before the error is reported.

2. The error only occurs going down from host to guest, so I assume these are reads. I can copy from guest up to the host without any problems.

3. The problem goes away when I switch from bridge mode networking to Nat mode. This is inconvenient, however, but I guess I can live with it.

4. If I move the guest to a ubuntu system on my local lan, it sees the file shares over my wired lan and has no trouble copying files in either direction. I don't have any problems accessing the guest files from the host, but this is not how I normally have the problem. I don't know how to access linux file shares from an xp guest on the same hardware, so I don't know if this is a meaningful data point.

5. Drag/drop from host to guest (xp to xp) works ok.

6. Some discussions mentioned turning off certain hardware options that have the words "offload" and "checksum" in them. I've tried these and they don't help. (they are only there on my host's network card - an intel 82566dc gigabit on-board nic as part of my intel mb)

Anyone have anything new to report on this?

[AWo]

Bridged uses the physical network card, so packets are going out on the wire and come back over the same one, through the same NIC. That's not the case with the virtual network. You can add a second NIC to each guest to connect th eguests and the host via a virtual network (host-only, for example). BTW, using this configuration makes you independent from the physical network link status in regards to host/guest connections.

AWo

VCP 3 & 4

\[:o]===\[o:]

=Would you like to have this posting as a ringtone on your cell phone?=

=Send "Posting" to 911 for only $999999,99!=

[rocket888]

If the data is written out to the nic by the host and then read by the guest from the same nic, is this done concurrently? Or does it pass to my router which buffers it and then passes it back to the nic?

If this second method is true, could the problem be in some way related to my lynksys router?

I just did another test, where I have another computer, my laptop, on the network and I have no trouble copying the same data from the laptop to the guest (with host on xp). This is the problem with NAT, when in this mode, my guest cannot be seen by my laptop. Otherwise I wouldn't bother with bridged mode. I can do some port forwarding so I can get VNC into my guests from my laptop, but I don't know how to get file shares through.

For a problem that's been around so long, I would have thought vmware experts would have been able to resolve this by now.

[AWo]

If the data is written out to the nic by the host and then read by the guest from the same nic, is this done concurrently? Or does it pass to my router which buffers it and then passes it back to the nic?

Yes, it must cross the router. That's why I suggested to use the host-only network. No physical LAN is involved then.

I just did another test, where I have another computer, my laptop, on the network and I have no trouble copying the same data from the laptop to the guest (with host on xp).

Yes, the data is send by one NIC and receive by another one. You get more data per time moved this way.

This is the problem with NAT, when in this mode, my guest cannot be seen by my laptop.

You can make the guest visible in NAT mode, but that's not worth the effort. When you switch to NAT I you already use a virtual network, like host-only, called VMnet8. That means the packets don't hit the wire again.

If you redirect the appropriate ports, you can get you share to work via NAT. But why donÄ't you just add a second vNIC to the guest, type "host-only" and use that connection for file transfer?

For a problem that's been around so long, I would have thought vmware experts would have been able to resolve this by now.

I wouldn't call that a problem but physical limitations.

AWo

VCP 3 & 4

\[:o]===\[o:]

=Would you like to have this posting as a ringtone on your cell phone?=

=Send "Posting" to 911 for only $999999,99!=

[rocket888]

If you redirect the appropriate ports, you can get you share to work via NAT. But why donÄ't you just add a second vNIC to the guest, type "host-only" and use that connection for file transfer?

Are you suggesting that I set this guest up with 2 network connections, one that is bridged and one that is host only? Then the bridge would show up on other physical machines, and the host only would only be seen by the host?

How is host only different from nat, in both cases only the host knows that the guest is there, right? Or does nat allow for multiple guests under the same host to see each other, sort of how my local lan machines see each other, but not beyond the router? Is vmnet8 acting like a virtual router?

If I got this right, then how will it decide to use the host only connection for file sharing between host and guest rather than use the bridged route. Will it do this because there's one less hop - I'm kinda out of my field here, but understand a little bit of tcp/ip.

I know my xp laptop can have 2 connections, ethernet and wifi, but it seems to me that it chooses whichever one was the first to connect. And I also seem to recall that if it's using one and I disconnect that, it doesn't fail over to the other. I know because I tried pulling the Ethernet while streaming a video to the laptop.

Is there a setting to force it to use the host only connection when guest and host communicate? I just learned how to use vmnetcfg, is there something in there that could be setup? Or is it done at the windows guest level.

> I wouldn't call that a problem but physical limitations.

I'm curious, the packet goes out to the router from the host - is it the router that then doesn't understand how to send it back? Why does it only fail in one direction (host to guest). Also, why does it work for small files and only fails on larger transfers? Is this a problem with windows xp alone, what about other guests?

And thanks for the help!