Re: Network Connectivity Problem

In news:7B1B3CFB-75F4-42F4-AE81-E3A0679296E2@xxxxxxxxxxxxx,
Michael <Michael@xxxxxxxxxxxxxxxxxxxxxxxxx> typed:
Hi All,

I am having a network connectivity problem with a number of Windows
servers.

Platform: All servers are virtualised on VMWare ESX 2.5
OS: Windows 2000 Server, and Windows 2003

History
Several months ago I noticed that one of my applications starting
displaying runtime errors. I eventually figured out this was a
network problem. The network connection would drop for a minute, then
return. I could not figure out why the network connection was
dropping, so I started a continuous ping from the server to our
proxy. Once I did this, no other network problems occurred. When I
stopped the continuous ping, a few minutes, hours later the network
connection would drop and come back again after a minute or so. I
left the continuous ping on, hoping to fox the problem at a later
date.

Shortly afterwards, I noticed that other servers were acting in the
same way. They were only minor servers, so I temperaly solved the
problem using the above solution.

Currently
We are migrating to a Windows 2003 domain. One of our domain
controllers which is also our fileserver is displaying the above
problems, only worse. When the network connection drops, it does not
return .

Troubleshooting Steps Carried Out
.When I changed the duplex setting from Auto to 100 Full, the network
connection immediately came back. Stopped continuous ping
.Connection then dropped an hour later.
.Restart server and started continuous ping
.Server stayed up for several hours, so stopped continuous ping
.Connection dropped shortly afterwards
.Switched physical network card and set to Auto
.Connection dropped
.Started continuous ping
.Connection stayed up
.Changed duplex to 100 full and stopped continuous ping
.Connection dropped just over an hour later

Conclusion
.Switch Problem -Ruled this out. I have checked the switch logs, and
no errors. Several other servers are working perfectly and are using
the same port on the switch.
.Faulty NIC - Ruled this out, as several other windows servers are
using the same physical NIC's and I also changed NICs.
.VMWare Problem - Each VM is configured as it should. Most VMs are
running fine with no problems. These servers are the only ones. They
are using the same hardware as the others. That's why I'm thinking it
must be a windows setting that's causing this.
.NIC Settings- Ruled out. Same errors on Auto and 100/Full , which is
what the switch is set to

All ideas greatly appreciated.

Proxy? Is it ISA? If so, is the ISA client installed on your machines?

--
Regards,
Ace

This posting is provided "AS-IS" with no warranties or guarantees and
confers no rights.

Ace Fekay, MCSE 2003 & 2000, MCSA 2003 & 2000, MCSE+I, MCT,
MVP Microsoft MVP - Directory Services
Microsoft Certified Trainer

Infinite Diversities in Infinite Combinations

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