I have been trying to establish federation between 2 exchange servers (different external domains) to share free/busy information. I was able to do so, however, only without KEMPs. So, if HTTPS is pointing (from outside) directly to exchange server (NAT-ed), it works. however, using LB in place, it does not, regardless of what template is being used.
To give you idea, federation can be tested on the exchange server with the Get-FederationInformation -domainName <domain> which will query the domain and try to find it. It basically tries to connect via AutoDiscover but noa via standard autodiscover URL http://autodiscover." + domain + "/autodiscover/autodiscover.xml but rather with https://autodiscover.mydomain.com/autodiscover/autodiscover.svc/wssecurity
With KEMP in place, it does not work, without, it does. Any idea?