I'm in the middle of moving our exchange organization from 2010 to 2013. I have 2 dag 2010 servers with all roles on each. No CAS array. I also setup dag with 2 2013 all roles. I'm using round robin to balance incoming traffic to new 2013 servers. I know NLB would be better but the nature of our multi-office environment will not allow NLB to function properly.
So far so good.
I created few test mailboxes on old servers and successfully migrated them to new servers. Outlook Anywhere worked fine on the inside and on the outside. Outlook picked up new servers without the problem after restart. Mobile devices have to be reconfigured for new servers and Im okay with that.
I'm concerned about mail flow. It flows fine between mailboxes on new servers. It also flows fine from mailboxes on old servers to mailboxes on the new servers. It gets delayed and eventually fails latter when sent from mailboxes on the new servers to mailboxes on the old servers.
I checked DNS and everything seems to be in order. Round Robin is also setup on the inside and servers can reach each other with public DNS.
Not sure if this is relevant to the problem I have but I ran "Remote connectivity Analyzer" and it fails " RPC over HTTP connectivity failed. " I also ran Test-OutlookConnectivity -ProbeIdentity "OutlookRpcCTPProbe" and it completes successfully