Please excuse my ignorance, I'm learning. Network structure - SonicWall (serves DHCP) --- Hub (working on replacing with a switch) ------ 2008 R2 Hyper-V Server --------- 2008 R2 Primary Domain Controller/Primary DNS --------- Other VM's ------ 2003 Server/Secondary DNS ------ 2008 R2 Application Server ------ ~10 Client computers (90% Windows 7) Details Everything worked perfectly for months, then after a power outage (DC went down) we have been experiencing some problems. After a fresh reboot on the Hyper-V (and subsequently the DC) everything works fine for about 8 hours. I'll return to work the next day and the latency on the network is >200ms for 80% of the packets and 20% being dropped. Connectivity still is there, it's just REALLY slow. We have some applications that rely on network shares from the 2008 R2 application server and obviously they become unacceptably slow. I have played with DNS settings, as that was my first hunch and was unsuccessful. I have enabled and disabled IPv6 and was unsuccessful. I've monitored network traffic using TCPView on the Hyper-V server and the DC and didn't notice anything bandwidth. I have a brand new Cisco switch in the mail to replace the old 3com hub, but I'm afraid that it's software related. The only solution (which is more like a patch) is to reboot the Hyper-V server, but then again it will have the problem again ~8 hours later. Any suggestions? Let me know what other type of information you may need in helping me diagnose the problem. Thank you in advance, James

This sounds a lot like a routing loop. Regards, Dave Patrick .... Microsoft Certified Professional Microsoft MVP [Windows] Disclaimer: This posting is provided "AS IS" with no warranties or guarantees , and confers no rights.

This sounds a lot like a routing loop. Regards, Dave Patrick .... Microsoft Certified Professional Microsoft MVP [Windows] Disclaimer: This posting is provided "AS IS" with no warranties or guarantees , and confers no rights.

Hi James, Thanks for posting here. So the symptoms is that we are facing slow performance issue to access this Hyper-V server form other hosts where in same subnet after about 8 hours when hyper-v server rebooted . So what if access other hosts in this network ?or we just get slow when access this particular Hyper-V and VMs on it? Any error or warring on this Hyper-V host ? Since the information is not quite enough to troubleshoot and will suggest to first upgrade the latest firmware for NIC on Hyper-V server and path the latest service pack and hotfixes in case any know issue: Hyper-V new performance updates http://blogs.technet.com/b/mkleef/archive/2011/04/27/hyper-v-new-performance-updates.aspx Hyper-V Update List for Windows Server 2008 R2 http://technet.microsoft.com/en-us/library/ff394763(WS.10).aspx http://blogs.technet.com/b/yongrhee/archive/tags/network/ And please also verify the routing table on these hosts in case the potential cause Dave mentioned. Thanks. Tiger LiTiger Li TechNet Community Support

Hi James, Thanks for posting here. So the symptoms is that we are facing slow performance issue to access this Hyper-V server form other hosts where in same subnet after about 8 hours when hyper-v server rebooted . So what if access other hosts in this network ?or we just get slow when access this particular Hyper-V and VMs on it? Any error or warring on this Hyper-V host ? Since the information is not quite enough to troubleshoot and will suggest to first upgrade the latest firmware for NIC on Hyper-V server and path the latest service pack and hotfixes in case any know issue: Hyper-V new performance updates http://blogs.technet.com/b/mkleef/archive/2011/04/27/hyper-v-new-performance-updates.aspx Hyper-V Update List for Windows Server 2008 R2 http://technet.microsoft.com/en-us/library/ff394763(WS.10).aspx http://blogs.technet.com/b/yongrhee/archive/tags/network/ And please also verify the routing table on these hosts in case the potential cause Dave mentioned. Thanks. Tiger LiTiger Li TechNet Community Support