What is the best way to configure Exchange 2010 routing in the following senario

I have a question regarding routing setup for Exchange 2010

I analyzed the current routing using Exchange Routing Viewer

We are currently running coexistence with Notes using CMT binary tree and Exchange 2010
We have two data centers (NY & California) and two regions regionA and regionB with their own just one Exchange 2010 server (CA/HB/MB) in each region

In NY data center there are 2 HB/CAS servers and 3 MBs servers

In California data center there are also 2 servers with two roles (HB/CAS) installed on each, and 3MB servers.
The connectivity is great between two data centers (1GB connection).
Currently ALL 10 servers (5 srvrs in CA and 5 srvs in NY) are in the same site with the total active directory cost set to 0. Also, each
Region A has one Exchange 2010 with all three roles installed.
RegionB is same as region A

What is the best way to configure routing? Also, how does load balancing works for Hub transport role. Currently cisco hardware load balancer is used for the CAS servers, but I don’t see from the Routing Group that DNS round robin is enabled for the HUB transport servers. How does the traffic is redistributed in my scenario if all servers are in the same site.

Can you be as detailed as possible and send me links to documentation regarding best way setting up servers in the similar scenarios.
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Beyond Next SolutionsSolutions ArchitectCommented:
Mailbox server to Hub Transport server (intra-Active Directory site)   The Microsoft Exchange Mail Submission service on Mailbox servers automatically load balances between all available Hub Transport servers in the same Active Directory site. Ref: http://technet.microsoft.com/en-us/library/dd638137.aspx

You can use your HWLB for Hub HA for inbound SMTP, or just use multiple MX records.

Check this for more details on how message routing occurs with the HT role:

And this for more info on SMTP failover and load balancing in the 2010 transport roles: http://technet.microsoft.com/en-us/library/ff634392.aspx

Regarding you question
How does the traffic is redistributed in my scenario if all servers are in the same site.
all HT servers will be treated as local delivery since they are all in the same AD site.

What is the best way to configure routing?
Even if you have multiple AD sites with Send/Receive connectors between them, the HT will determine the location of the recipient's mailbox. If that mailbox resides on a MB server in a remote AD site, the HT will always first attempt direct delivery to a HT in the same site as the recipient's MB server. It ignores the AD site and site link topology unless all HT servers in the remote site are unreachable, then it will attempt to get the message to the HT server that is "closest" to the destination site based on AD site link costs (or the Exchange-specific cost of the AD site link if present).

So, since you have exchange 2010 in 2 different datacenters, here's what will happen:

Scenario 1: You keep everything as a single AD site

In this config, each HT that processes a message will directly deliver mail to the MB server that hosts the recipient's mailbox, regardless of location.

Scenario 2: You separate into 2 AD sites and configure a site link between them

Here, when a HT processes a message, it will first determine where the recipient exists, If the recipient mailbox is in the same site as the HT, it will deliver the mail via RPC/MAPI directly to the MB server hosting the user's mailbox. If it determine's the recipient's mailbox is in the remote site, it will send the message via SMTP-TLS across the site link to a HT in the remote site. The remote site's HT will then submit the message to the MB server hosting the recipient's mailbox over RPC/MAPI.

Just off instinct, and without knowing the details of your environment, scenario 2 is what I would propose you go with as it is the safe bet. If you have redundant, high speed low latency links (LAN equivalent) between sites, then scenario 1 would work. If there are firewalls between the 2 locations, Scenario 2 hands down!


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claudiamcseAuthor Commented:
Thank you.
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