We just started implementing Exchange 2007 SP1 into a current Exchange 2003 org. Everything is going as planned including SCR except for one aspect... Our org is as follows: 3 sites each site has Mailbox, Client Access, Hub Transport roles Our original plan was to have 1 web mail URL thats published on the internet (mail.domain.com) and use DNS round robin to distribute the load, and if/when a server is down we will remove that record from DNS. We'd like to use forms based authentication for a better experience for the end user. It doesnt look like this plan will work as it just wants to redirect the user to the proper CAS/mailbox server with a nice little message. If I drop the round robin portion of the plan and use 1 internet published CAS to proxy to the other CASes it works. This doesn't offer the redundancy I had hoped to build into the OWA org. Am I right in saying my plan to use round robin to serve up OWA from different geographical sites isn't going to work unless I add split the CAS and Mailbox roles between 2 servers in each site? If so I'll just have to drop the round robin idea as we don't have a budget to purchase 3 additional servers for our network. Thanks! Scott
Hi there, If you only have 1 CAS per AD Site, then the CAS that the user connects too will proxy to a CAS in the correct AD Site the users mailbox resides in if not externalurl is set and the RedirecttoOptimalOwaServer is set to false. If an externalurl is set and/or RedirecttoOptimalOwaServer is not set to false then the user will be redirected. User accessing CAS in AD Site that users mailbox is in: User > CAS > Mailbox User accessing CAS in AD Site that users mailbox is NOT in when externalurl is configured: User > CAS > redirect CAS in correct AD Site > Mailbox When RedirecttoOptimalOwaServer is configured or externalurl is not set: User> CAS > CAS proxies to CAS in correct AD Site > Mailbox So to achieve HA for either solution you will need two CAS' in each AD Site. Only one AD Site can have the CAS servers externally available and these can proxy to CAS servers in another AD Site if you want, however you still need more than 1 to achieve HA. Does that make sense? Oliver
Oliver, Thanks for the reply...You confirmed what I thought and it all makes sense. We wont be adding 2nd CAS servers so in the event of a failure we'll just update DNS accordingly. Scott "Oliver Moazzezi [MVP]" wrote: > Hi there, > > If you only have 1 CAS per AD Site, then the CAS that the user connects too > will proxy to a CAS in the correct AD Site the users mailbox resides in if > not externalurl is set and the RedirecttoOptimalOwaServer is set to false. > If an externalurl is set and/or RedirecttoOptimalOwaServer is not set to > false then the user will be redirected. > > User accessing CAS in AD Site that users mailbox is in: > > User > CAS > Mailbox > > User accessing CAS in AD Site that users mailbox is NOT in when externalurl > is configured: > > User > CAS > redirect CAS in correct AD Site > Mailbox > > When RedirecttoOptimalOwaServer is configured or externalurl is not set: > > User> CAS > CAS proxies to CAS in correct AD Site > Mailbox > > > So to achieve HA for either solution you will need two CAS' in each AD Site. > Only one AD Site can have the CAS servers externally available and these can > proxy to CAS servers in another AD Site if you want, however you still need > more than 1 to achieve HA. > > Does that make sense? > > Oliver > > >
> Thanks for the reply...You confirmed what I thought and it all makes > sense. > We wont be adding 2nd CAS servers so in the event of a failure we'll just > update DNS accordingly. Hey no problem. Remember the HT and CAS roles can be combined if you don't want any more cost associated with your project but still want to get that second CAS per AD site. Oliver
