I am planning to transition from a single Ex2003 server to 4 servers, 2 Mailbox servers with CCR and 2 combined HUB/CAS servers with NLB, no edge servers. I've never setup a NLB before, and I wonder in what order I should install everything. The CAS/HUB servers should be deployed (and configured) first I know. But should NLB be setup before or after Ex2007 installation? If anyone could tell me if this is correct setup, it would help a lot: NLB virtual IP: 172.16.10.20, FQDN: mail.domain.com.The virtual IP will be NAT'ed trough firewall into 172.16.10.20. Our current Ex2003 server is NAT'ed already like this. Port rules: all the necesaary ports, set to single affinity in unicast mode. Server1: CAS1 (both HUB and CAS)2 nicsnic1: IP 172.16.10.221, 255.255.255.0, gw 172.16.10.1, DNS servers 172.16.10.17 and 172.16.10.18, domain suffix internal.domain.com, WINS server 172.16.10.17nic2: IP 172.16.10.231, 255.255.255.0, no gw or DNS settings, no domain suffix. NLB enabled, adding the NLB virtual IP to the list of IP adresses on nic2, so nic2 has both 172.16.10.231 and 172.16.10.20. Making sure that nic1 is on top of priority of nics.I tried to read all the documentation about NLB, but I cannot find out if both nics should be or not on the same subnet. As fars I've read, the NLB nic should have gw/dns settings at all, only IP and subnet. Server2: CAS1 (both HUB and CAS)2 nicsnic1: IP 172.16.10.222, 255.255.255.0, gw 172.16.10.1, DNS servers 172.16.10.17 and 172.16.10.18, domain suffix internal.domain.com, WINS server 172.16.10.17nic2: IP 172.16.10.233, 255.255.255.0, no gw or DNS settings, no domain suffix. NLB enabled, adding the NLB virtual IP to the list of IP adresses on nic2, so nic2 has both 172.16.10.232 and 172.16.10.20. Making sure that nic1 is on top of priority of nics. About hostnames and FQDN, I am a little confused. The plan is to provide OWA for outside users, what FQDN should I type on the NLB virtual hostname/FQDN? All the servers would be located on the inside of the firewall, so NAT is used on the CAS servers. Our AD domain is using internal.domain.com namespace, does NLB FQDN have to be the same or should it be mail.internal.domain.com? Also, on the server configuration on Exchange 2007 console, on each server under CAS configurations, on the OWA tab on owa(default website), if I use https://mail.internal.domain.com/owa as the internal URL and https://mail.domain.com/owa, then OWA would be NLB right? A final question, if a user is logged on OWA in a NLB cluster and one of the servers goes down, what happens with the session for the users logged in? Do they continue to work without any users knowing it, or would they be logged off and have to log in again?

Hi, Before we move on, we shall know that NLB can be used to provide high availability in the following scenarios: 1. Load balancing of inbound SMTP connections for POP and IMAP client connections to the default Receive connector named "Client <Server Name>" that is created only on Hub Transport servers. 2. Load balancing of inbound SMTP connections for applications that submit e-mail to the Exchange organization. NLB should not be used to distribute connections for internal routing between Hub Transport servers. Besides,NLB is only avaliable on Exchange 2007 with SP1 installed. 1. For the first question: should NLB be setup before or after Ex2007 installation? NLB should be configure after we have these roles have installed. 2. IP address you want to use as the Windows NLB cluster IP address should be an IP address on the same subnet as the NLB member servers. 3. When we begin to setup NLB the first thing is to do is to create an A-record for the NLB cluster name in DNS. So that we can use these two Hub transport/Client Access server as one. Then you have to point your MX record to Windows NLB cluster IP address, which you specified when you create the A record. So that Client will find the Hub transport/Client Access server. 4. Yes, you are right. Internally, you can use https://mail.internal.domain.com/owa ,external URL should be the https://mail.domain.com/owa More information share with you: How you can load-balance Exchange Server 2007 Service Pack 1 (SP1) Hub Transport Servers using Windows Network Load Balancing technology. http://www.msexchange.org/articles_tutorials/exchange-server-2007/planning-architecture/load-balancing-exchange-2007-sp1-hub-transport-servers-windows-network-load-balancing-technology-part1.html Using Network Load Balancing http://technet2.microsoft.com/windowsserver/en/library/57c24429-0268-4ed8-afdf-fd4b0b6539b71033.mspx?mfr=true Hope it helps. Xiu

What domean " Load balancing of inbound SMTP connections for POP and IMAP client connections" I don't understand how POP and IMAP are relevant. Are you just saying a non-RPC client? Or am I to understand that the CAS roles go through a NLB balance HUB role to retrieve mail from the mailbox? Thanks Phil Waters