As with Exchange Server 2007, Exchange Server 2010
has various roles that can be installed on the server to perform
specific functions. There are five major server roles, most of which are
modular and can reside on a single server (for small environments) or
be distributed to multiple servers throughout an organization.
The roles are as follows:
Edge Transport server role
Client Access server role
Hub Transport server role
Mailbox server role
Unified Messaging server role
Edge Transport Server Role—Establishing Perimeter Security
The Edge Transport
server role provides antivirus and antispam message protection for the
Exchange Server infrastructure. Edge Transport servers act as message
hygiene gateways and are designed to reside in a perimeter network or
demilitarized zone (DMZ). This allows them to block harmful traffic before it reaches the corporate network.
Edge Transport servers are often utilized as the SMTP gateway for sending and receiving mail to and from the Internet.
Client Access Server Role—Providing User Connectivity
As its name
suggests, a client access server is responsible for providing
connectivity between the user community and their data. Like the
front-end servers found in Exchange Server 2003, client access servers
manage connectivity via Outlook Web Access and ActiveSync, and like the
client access servers in Exchange Server 2007, they also manage
connectivity from POP and IMAP users.
In Exchange Server
2010, however, the client access servers also manage MAPI (such as
Outlook) client connectivity. In a pure Exchange Server 2010
environment, clients never have to connect directly to their mailbox
servers—all connectivity is to the client access server.
By taking
responsibility for managing these additional connections, client access
servers allow Mailbox servers to focus on their primary role—processing
messaging requests.
Hub Transport Servers—Routing the Mail
The Hub Transport
server role is responsible for moving mail between Exchange Mailbox
servers, similar to how bridgehead servers worked in the past. This role
can be configured on a dedicated server or it can be deployed on an
existing mailbox server.
A Hub Transport server must
be deployed in each Active Directory site that contains an Exchange
Server 2010 Mailbox server, as all message routing in other sites goes
through one or more Hub Transport servers.
Even if the sender and
recipient are on the same Mailbox server, the message will route through
a local Hub Transport server. This ensures that all messages are
subject to any transport rules that may be configured for the
environment.
Unified Messaging Servers—Combining All the Data
The Unified Messaging
server role was introduced with Exchange Server 2007. It acts as a
gateway for combining email, voice, and fax data into a single mailbox.
All this data can be accessed via the mailbox or a telephone.
Mailbox Servers—What It’s All About
The Mailbox server
role is the core role within Exchange Server 2010. Without mailbox
servers to store the user data, all of the other server roles would be
without purpose.
The Mailbox servers host mailboxes and mail enabled objects such as contacts and distribution lists.
