Multicast NLB "Gustavo Barreto" <barreto[ at ]quattuor.com.br> 04.07.2007 22:32:57 A few weeks ago we discovered that our NLBs servers were flooding traffic to all switches in the network. This problem was affecting network performance, since traffic directed to NLB servers was flooded to the whole network. The NLB servers are used for Terminal Services and a lot of users depend on it to do their work. Searching for a solutions we found some articles recommending to configure NLB to use multicast (with IGMP) and to setup igmp snooping in layer 2 switches (we have a Cisco 2960 switch connected to this servers). Even configuring the switches to operate in multicast mode flooding continues. The switches don't recognize NLB traffic sent through the switches. Viewing some other articles we found that configuring multicast don't stop flooding and that the correct solution is to connect NLB servers to a hub. Can someone tell me what are the best option to limit flooding? And also point me some documentation to configure e troubleshoot this problem? Regards, Gustavo Barreto

Re: Multicast NLB "Russ Kaufmann [MVP]" <russ[ at ]clusterhelp.com> 05.07.2007 20:56:19 "Gustavo Barreto" <barreto[ at ]quattuor.com.br> wrote in message news:%23xO0GtovHHA.4528[ at ]TK2MSFTNGP03.phx.gbl... [Quoted Text] >A few weeks ago we discovered that our NLBs servers were flooding traffic >to > all switches in the network. This problem was affecting network > performance, > since traffic directed to NLB servers was flooded to the whole network. > The > NLB servers are used for Terminal Services and a lot of users depend on it > to do their work. Searching for a solutions we found some articles > recommending to configure NLB to use multicast (with IGMP) and to setup > igmp > snooping in layer 2 switches (we have a Cisco 2960 switch connected to > this > servers). Even configuring the switches to operate in multicast mode > flooding continues. The switches don't recognize NLB traffic sent through > the switches. > > Viewing some other articles we found that configuring multicast don't stop > flooding and that the correct solution is to connect NLB servers to a hub. > > Can someone tell me what are the best option to limit flooding? And also > point me some documentation to configure e troubleshoot this problem? Some reading for you. http://msmvps.com/blogs/clusterhelp/archive/2005/08/07/61965.aspx http://msmvps.com/blogs/clusterhelp/archive/2006/06/05/99532.aspx http://msmvps.com/blogs/clusterhelp/archive/2006/06/24/102772.aspx http://technet2.microsoft.com/windowsserver/en/library/8d2e0b4f-4dfd-4893-9505-124ddf4fc2f01033.mspx?mfr=true http://technet2.microsoft.com/windowsserver/en/library/c7da3162-2055-438d-87c1-c1086c694c9f1033.mspx?mfr=true -- Russ Kaufmann MVP - Windows Server - Clustering ClusterHelp.com, a Microsoft Certified Gold Partner Web http://www.clusterhelp.com Blog http://msmvps.com/clusterhelp The next ClusterHelp classes are: July 10-13 in Denver July 16-19 in New York Sep 3 - 6 in Copenhagen

Re: Multicast NLB "Gustavo Barreto" <barreto[ at ]quattuor.com.br> 05.07.2007 23:01:21 Hi Russ, Thank you for your assistance. Now NLB is becoming a little more clear to me :D To operate in multicast mode you recommend to use a hub and the hub connect the switch. I read a lot of articles about NLB and some of them were conflicting. Some documents, but i thanks a lot. Best Regards, Gustavo Barreto "Russ Kaufmann [MVP]" <russ[ at ]clusterhelp.com> wrote in message news:005DBFF1-D812-4DF5-889C-8805335D8B8F[ at ]microsoft.com... [Quoted Text] > "Gustavo Barreto" <barreto[ at ]quattuor.com.br> wrote in message > news:%23xO0GtovHHA.4528[ at ]TK2MSFTNGP03.phx.gbl... >>A few weeks ago we discovered that our NLBs servers were flooding traffic >>to >> all switches in the network. This problem was affecting network >> performance, >> since traffic directed to NLB servers was flooded to the whole network. >> The >> NLB servers are used for Terminal Services and a lot of users depend on >> it >> to do their work. Searching for a solutions we found some articles >> recommending to configure NLB to use multicast (with IGMP) and to setup >> igmp >> snooping in layer 2 switches (we have a Cisco 2960 switch connected to >> this >> servers). Even configuring the switches to operate in multicast mode >> flooding continues. The switches don't recognize NLB traffic sent through >> the switches. >> >> Viewing some other articles we found that configuring multicast don't >> stop >> flooding and that the correct solution is to connect NLB servers to a >> hub. >> >> Can someone tell me what are the best option to limit flooding? And also >> point me some documentation to configure e troubleshoot this problem? > > Some reading for you. > http://msmvps.com/blogs/clusterhelp/archive/2005/08/07/61965.aspx > http://msmvps.com/blogs/clusterhelp/archive/2006/06/05/99532.aspx > http://msmvps.com/blogs/clusterhelp/archive/2006/06/24/102772.aspx > http://technet2.microsoft.com/windowsserver/en/library/8d2e0b4f-4dfd-4893-9505-124ddf4fc2f01033.mspx?mfr=true > http://technet2.microsoft.com/windowsserver/en/library/c7da3162-2055-438d-87c1-c1086c694c9f1033.mspx?mfr=true > > > -- > Russ Kaufmann > MVP - Windows Server - Clustering > ClusterHelp.com, a Microsoft Certified Gold Partner > Web http://www.clusterhelp.com > Blog http://msmvps.com/clusterhelp > > The next ClusterHelp classes are: > July 10-13 in Denver > July 16-19 in New York > Sep 3 - 6 in Copenhagen

Re: Multicast NLB "Russ Kaufmann [MVP]" <russ[ at ]clusterhelp.com> 06.07.2007 07:56:45 "Gustavo Barreto" <barreto[ at ]quattuor.com.br> wrote in message news:edUyoh1vHHA.412[ at ]TK2MSFTNGP04.phx.gbl... [Quoted Text] > Hi Russ, > > Thank you for your assistance. Now NLB is becoming a little more clear to > me :D > To operate in multicast mode you recommend to use a hub and the hub > connect the switch. I read a lot of articles about NLB and some of them > were conflicting. > Some documents, but i thanks a lot. I don't recommend multicast. The best practice is to use unicast with two NICs, one for NLB and the other for management. When it comes to flooding, using a hub will work, but most people that I know use VLANs in their switches. -- Russ Kaufmann MVP - Windows Server - Clustering ClusterHelp.com, a Microsoft Certified Gold Partner Web http://www.clusterhelp.com Blog http://msmvps.com/clusterhelp The next ClusterHelp classes are: July 10-13 in Denver July 16-19 in New York Sep 3 - 6 in Copenhagen