We have distributed caching software (NCache, to be specific) that is deployed on two Windows 2003 x64 servers. The software is configured to run several caches, all in "replicated" mode (this is a typical active-passive failover clustering -- i.e. clients talk to one server, and that server copies all the data over to the second box so that if the first machine was ever to come offline, the second one would take over. Note, that this is not Windows clustering -- all the replication and failover is handled by NCache).
Everything worked fine for several months, but couple weeks ago we started seeing exceptions related to replication in the NCache log. The exceptions occurred once every several days, and did not appear to be predictable. NCache support basically said "check your network". Which we did. We found and resolved an issue (the details are too long to explain, the main point is that there was a high number of network collisions reported by both the network drivers on the second server, and the switch that server is connected to).
That was a week ago. After the network was fixed, the exceptions went away, and we thought that everything is OK. But today we got the exact same replication exception again. The only difference is that neither network drivers on the box nor the switch report any errors. I saw question http://serverfault.com/questions/76113/monitor-network-drops-between-windows-server-2003-servers, but don't think we can run wireshark on those boxes -- the network traffic on them is averaging about 100Mbit during the day, and since it's all NCache traffic, it's just not realistic to capture it all for days while waiting for the hiccup to occur. Is there anything else we can do to know for sure if it's still the network?