dears, i'm installing NLB for 2 Hub/Cas exchange 2007 servers over teaming interfaces,so i used multicast mode with None affinity for all ports but when testing the OWA i faced the following: after providing the credentials the page flush and nothing happen. after providing the credentials i can login but it keep asking me to provide credentials again to avoid the above i changed the affinty To "single" for HTTP and Https I need ur recommendation regarding the "uniCast,MuliCast" & Affinty" None,Single,class C" over Single NIC.mwahab

HI Wahab, I would suggest you to go for SINGLE NIC configuration for NLB Array on your CAS Server, sometimes I has observed that whenever we use NLB Private NIC as a TEAM NIC then, we face issue. Afterwards, once you configure your NLB for single NIC as private interface for your NLB Array, then it does not matter that weather you use MULTICAST or UNICAST. Multicas is recommended when you have seperate NICs as a PUBLIC interface & private interface. UNICAST is recommnedd as opposite as I descirbed above for multicast. Regards, ZahirZahir Hussain Shah MCP, MCSE, MCTIP Enterprise Admini, CCNA, ITIL Senior Infrastructure Consultant zhshah@live.com United Arab Emirates

Hi Wahab, For the second point : after providing the credentials i can login but it keep asking me to provide credentials again Your exchange server is't published by ISA Server. If it the case then I hink that youhave activate the authentication on bothe Exchange server and ISA server (on Listner settings). Regards. Fenecit

Typically NLB and teaming does not mix at all. Both technologies depend on MAC address magic and now you're mixing them - you'll break one or the other. As for Zahir's suggestion about using a single NIC, that won't work with unicast unless you're on WS08R2. Since you're running Exchange 2007 that's not possible. If you want to do unicast (which works with the most switches), you need two *indepedent* NICs. For multicast (which may require some config work on your switches), you can use one NIC.Active Directory, 4th Edition - www.briandesmond.com/ad4/

Hi Wahab, Unicast - Each NLB cluster node replaces its real (hard coded) MAC address with a new one (generated by the NLB software) and each node in the NLB cluster uses the same (virtual) MAC. Because of this virtual MAC being used by multiple computers, a switch is not able to learn the port for the virtual NLB cluster MAC and is forced to send the packets destined for the NLB MAC to all ports of a switch to make sure packets get to the right destination. Multicast - NLB adds a layer 2 MAC address to the NIC of each node. Each NLB cluster node basically has two MAC addresses, its real one and its NLB generated address. With multicast, you can create static entries in the switch so that it sends the packets only to members of the NLB cluster. Mapping the address to the ports being used by the NLB cluster stops all ports from being flooded. Only the mapped ports will receive the the packets for the NLB cluster instead of all ports in the switch. If you don't create the static entries, it will cause switch flooding just like in unicast. Some other information for you: http://support.microsoft.com/kb/278431 http://technet.microsoft.com/en-us/library/cc756878(WS.10).aspx Regards! gavin

Dear Gavin / Brain, First of all thanks for your support, and afterwards I would like to ask a question regarding on NLB deployment, which I did today, and I was facing the below issue: Enviornment Details: TWO NODE NLB ARRAY on Windows Server 2008 R2, EE Application : Exchange Server 2010, EE No. of NICs on each NODE : TWO NICs Scenario: I build NLB ARRAY with both UNICAST & MULTICAST configuration type, but with both UNICAST & MULTICAST, I faced issue, that my Exchange 2010 CAS/HUB Servers are not accessable with the VIRTUAL DNS ENTRY or IP ADDRESS from all other VLANs (other than SERVER VLAN). Please tell me what type of NLB Configuration should I select for my case, means UNICAST or MULTICAST, and how I can configure my CISCO CORE SWTICHES for allowing me to ACCESS this Exchange 2010 CAS NLB ARRAY from other VLANs of my Network. Thanks Zahir Hussain Shah zahirjajee@hotmail.com with both configurations, my Exchange 2010 CAS/HUB NLB is not accessable from all other VLANs on my core-cisco switch. Zahir Hussain Shah MCP, MCSE, MCTIP Enterprise Admini, CCNA, ITIL Senior Infrastructure Consultant zhshah@live.com United Arab Emirates

Hi Per my known, the Network Load Balancing driver does not support a mixed unicast and multicast environment. All cluster hosts must be either multicast or unicast; otherwise, the cluster will not function properly. Some other information for you about how to plan the NLB network: http://blogs.technet.com/networking/archive/2008/11/20/balancing-act-dual-nic-configuration-with-windows-server-2008-nlb-clusters.aspx http://blogs.technet.com/networking/archive/2008/05/15/preparing-the-network-for-nlb-2008.aspx http://blogs.technet.com/networking/archive/2009/01/15/unable-to-connect-to-windows-server-2008-nlb-virtual-ip-address-from-hosts-in-different-subnets-when-nlb-is-in-multicast-mode.aspx Or, you could post your issue on below forum, you would get more help from there: http://social.technet.microsoft.com/Forums/en-us/winserverClustering/threads Regards! gavin

RESOLVED!!! Previously I was testing my Exchange 2010 CAS NLB with the following design: 2 HUB / CAS servers have 2 NICS (NIC-1LAN, NIC2-HeartBeat) MULTICAST but I was not able to ping the NLB Virtual IP Address / FQDN from the NON-SERVER VLANS (CLIENT VLAN). Resolution: 1-Recreated NLB by selecting the dedicated Interface as the LAN CARD (SERVER LAN CARD). 2-ADD THE VIRTUAL IP ADDRESS from the same VLAN of SERVER VLAN 3-Selected UNICAST 4-Selected default settings for INFINITY (SINGLE) 5-ALL PORTS (0-9***) 6-Added another NLB Node except all the above steps I didnt done anything, and my NLB is still able to ping fromt all VLANs, and later on I also created the CAS ARRAY for Exchange, and everything is working good. Zahir Hussain ShahZahir Hussain Shah MCP, MCSE, MCTIP Enterprise Admini, CCNA, ITIL Senior Infrastructure Consultant zhshah@live.com United Arab Emirates

RESOLVED!!! Previously I was testing my Exchange 2010 CAS NLB with the following design: 2 HUB / CAS servers have 2 NICS (NIC-1LAN, NIC2-HeartBeat) MULTICAST but I was not able to ping the NLB Virtual IP Address / FQDN from the NON-SERVER VLANS (CLIENT VLAN). Resolution: 1-Recreated NLB by selecting the dedicated Interface as the LAN CARD (SERVER LAN CARD). 2-ADD THE VIRTUAL IP ADDRESS from the same VLAN of SERVER VLAN 3-Selected UNICAST 4-Selected default settings for INFINITY (SINGLE) 5-ALL PORTS (0-9***) 6-Added another NLB Node except all the above steps I didnt done anything, and my NLB is still able to ping fromt all VLANs, and later on I also created the CAS ARRAY for Exchange, and everything is working good. Zahir Hussain Shah Zahir Hussain Shah MCP, MCSE, MCTIP Enterprise Admini, CCNA, ITIL Senior Infrastructure Consultant zhshah@live.com United Arab Emirates HI All, i have the similar problem--- i have 2 Base servers and i have created 2 VM on each servers through Microsoft VM. Teaming is enabled on 1 Base server but another server is running with single NIC. I have installed HUB/CAS on a virtual server and mailbox on another Virtual server, and configured Unicast NLB and after NLB configuration i statically defined NLB MAC address as HUB/CAS servers MAC and enabled MAC spoofing. Now users are able to connect to exchange via MAPI and OWA but POP3 and IMAP4 is not connecting internally, as well users are getting password prompt intermitently... Kindly suggest.......