We have updated to Exchange 2013 CU6 w/ coexistance with 2007. We've migrated all resouces and settings to exchange 2013 and have shutdown the 2007 environment (3 weeks ago) with no negative impact.
An issue we've been dealing with for about 2.5 months is client connectivity. Randomly all outlook users will disconnect and email will no longer be delivered to mobile devices. There are no log entries leading up to the failure or during.
To resolve the issue I do the following:
Reboot both CAS servers
Make the active node passive and the passive node active
Client connectivity restored
**Note: After talking with multiple VARs and collegues I now know that NLB clusters are not recommended by Microsoft and we should be using hardware for load balancing. We're in the process of purchasing a hardware load balancer, but we're 2 month from having one in house.
Front End- 2 virtual Windows server 2012 R2 on VMware 5.1. Each have 2 cpu and 8gb ram. Running Exchange server 2013 cu6 Standard in A active/passive NLB configuration (unicast).
Back End- 2 virtual Windows server 2012 R2 on VMware 5.1. Each 12 cpu and 32gb ram. Running Exchange server 2013 cu6 Standard in a DAG.
1. Has anyone seen this behavior before?
2. Any suggestions on tools/troubleshooting?
We've used the following VMware links to configure and QC server settings:
3) VMware: Articles and Blog
• Microsoft Network Load Balancing Multicast and Unicast operation modes (1006580)
• Sample Configuration - Network Load Balancing (NLB) unicast mode configuration (1006778)
If your Windows Network Load Balancing is configure with unicast communication mode, review the section on RARP packets in this article .
The transmission of RARP packets is prevented on the portgroup / virtual switch as explained in the later part of the article.
Microsoft NLB not working properly in Unicast Mode (1556)
Check out this blog:
Back To Basics: Configuring Standard vSwitch (Part Two of Three)
Scroll to the “Notify Switches” section where you will see:
Microsoft NLB software when configured in a unicast mode is incompatible with Notify Switches set to Yes.
• Sample Configuration - Network Load Balancing (NLB) Multicast Mode Configuration (1006558)