Using Exchange 2013 (e2013), SP1.
Three locations.  (Let's say  Location-A, -B, and C.)
Each Location is an AD site, and physically "remote" from the others.
Each location will have one e2013 server,  each server running both CAS and Mailbox function.

The main location ( LOC-A) is where all external OWA and EAS will "enter" from the Internet, via a firewall.
The E2013 server there will "connect" (?) to the e2013 server for "this mailbox",...at any of the 3 locations.

What "special" configuration do we need on the 2 remote/other e2013 servers for OWA virtual directory (or similar).

It looked like it was working "out of the box".

Some users work OK, with no special changes to anything.

But some users have OWA in a "never ending wait" (browser appears to spin forever), 

and that might be due to a different Language at the other locations.

I guess Exchange knows how to "internally route" the OWA traffic from the LOC-A CAS to the LOC-B CAS.

(In Exchange 2007 we called this "Exchange CAS proxy" as I recall, but not sure that term is correct in e2013.)

Thanks.

==

Hi,

User-A logon OWA in L-B.

Based on my knowledge, if User-A logon OWA in L-B, CAS-B would accept the request first.

Then it detect the User-A's mailbox located in L-A. CAS-B will proxy this request to CAS-A.

I find a great blog for your reference:

Client Connectivity in an Exchange 2013 Coexistence Environment

http://blogs.technet.com/b/exchange/archive/2014/03/12/client-connectivity-in-an-exchange-2013-coexistence-environment.aspx

Thanks

Thanks for the reply.

Let me take a look at that blog, and then I will let you know...

=======

It is almost always confusing to me when someone marks these as "proposed answer" and then "marked as answer".

How do you know it was an answer for our situation ?

I appreciate you "taking a look". 

But suggest you should be very cautious about saying it was an answer, with no data to support that.

(Not just in this thread;   I have seen this several places in the forums.  )

===

This blog was posted Feb 11, 2015, and it has some useful information that addresses my question.

http://blogs.technet.com/b/exchange/archive/2015/02/11/configuring-multiple-owa-ecp-virtual-directories-on-the-exchange-2013-client-access-server-role.aspx

This part was of special interest, and answered part of my question.

==

You can achieve scenarios 1 and 2 out of the box with no additional configuration, specifically, no need for an additional web site. Yes, really.

==

Thanks for that.

Still researching the part about the "Language"

==