SMTP connectors, Active Directory sites, and Active
Directory links all have important roles to play in determining how
Exchange routes and delivers messages in your organization. You can
work with connectors, sites, and links in a variety of ways, but first
you need a strong understanding of how connectors are used.
1. Connecting Source and Destination Servers
Exchange Server 2010 uses SMTP connectors to represent logically the
connection between a source server and a destination server. How you
configure an SMTP connector determines how Exchange Server transports
messages using
that connection. Because each SMTP connector represents a one-way
connection, Exchange Server uses both Send and Receive connectors.
A Send connector is a logical gateway through which transport
servers send all outgoing messages. When you create a Send connector,
it is stored in Active Directory or in Active Directory Lightweight
Directory Services (AD LDS) as a connector object. Send connectors are
not scoped to a single server. Multiple servers can use a single Send
connector for sending messages. Send connectors deliver mail by looking
up a mail exchanger (MX) record on a DNS server, by looking up an
Address (A) record, or by using
a smart host as a destination. With DNS records, the DNS server
settings you configure on the Transport server are used for name
resolution. You can configure different settings for internal and
external DNS lookups if necessary.
A Receive connector is a logical gateway through which all incoming
messages are received. When you create a Receive connector, it is
stored in Active Directory or in AD LDS as a connector object. Unlike
Send connectors, Receive connectors are scoped to a single server and
determine how that server listens for connections. The permissions on a
Receive connector determine from whom the connector will accept
connections. The authentication mechanisms you configure for a Receive
connector determine whether anonymous connections are allowed and the
types of authentication that are permitted.
Exchange Server creates the Send and Receive connectors required for
mail flow when you install your Hub Transport servers. If your
organization also uses Edge Transport servers, Exchange creates the
additional Send and Receive connectors required during the Edge
Subscription process. You can also explicitly create Send and Receive
connectors or automatically compute them from the organization topology
using Active Directory sites and site-link information.
2. Viewing and Managing Active Directory Site Details
By default, Hub Transport servers use Active Directory sites and the
costs that are assigned to the Active Directory Internet Protocol (IP)
site links to determine the least-cost routing path to other Hub
Transport servers in the organization. You can override the Active
Directory costs with Exchange costs.
After a Hub Transport server determines the least-cost routing path,
the server routes messages over the link or links in this path, and in
this way, a source Hub Transport server relays messages to target Hub
Transport servers. By default, when there are multiple Active Directory
sites between the source
and destination server, the Hub Transport servers that are located in
Active Directory sites along the path between the source server and the
target server don't process or relay the messages in any way—with
several exceptions:
-
If you want messages to be processed en route, you can configure an
Active Directory site as a hub site so that Exchange routes messages to
the hub site to be processed by the site's Hub Transport servers before
being relayed to a target server. The hub site must exist along the
least-cost routing path between source and destination Hub Transport
servers.
-
If a message cannot be delivered to the target site, the Hub
Transport server in the closest reachable site along the least-cost
routing path of the target site queues the message for relay. The
message is then relayed when the destination Hub Transport server
becomes available.
Tip
To determine which Active Directory and global catalog servers a Hub
Transport server is using, click the System Settings tab in the
server's Properties dialog box. Expand the Server Configuration node,
and then select the Hub Transport node. Right-click the entry for the
transport server, and then select Properties. In the Properties dialog
box, click the System Settings tab.
You can use the Get-AdSite cmdlet to display the configuration details of an Active
Directory site. If you do not provide an identity with this cmdlet,
configuration information for all Active Directory sites is displayed.
Example 1 provides the syntax and usage, as well as sample output, for the Get-AdSite cmdlet. Note that the output specifies whether the site is enabled as a hub site.
Example 1. Get-AdSite cmdlet syntax and usage
Syntax
Get-AdSite [-Identity 'SiteIdentity']
[-DomainController 'DCName']
Usage
Get-AdSite -Identity 'First-Seattle-Site' | fl
Output
Runspaceid :
HubSiteEnabled : False
Partnerid : -1
Name : First-Seattle-Site
AdminDisplayName :
ExchangeVersion : 0.0 (6.5.6500.0)
DistinguishedName : CN=First-Seattle-Site,
CN=Sites,CN=Configuration,DC=cpandl,DC=com
Identity : cpandl.com/Configuration/Sites/First-Seattle-Site
Guid : dda814f3-2173-4943-bdd9-5ba8d6b6e5d7
ObjectCategory : cpandl.com/Configuration/Schema/Site
ObjectClass : {top, site}
WhenChanged : 12/17/2009 8:27:00 PM
WhenCreated : 12/17/2009 8:27:00 PM
WhenChangedUTC : 12/17/2009 3:27:00 AM
WhenCreatedUTC : 12/17/2009 3:27:00 AM
OrganizationId :
OriginatingServer : MAILSERVER25.cpandl.com
IsValid : True
You can use the Set-AdSite
cmdlet to configure an Active Directory site as a hub site to override
the default message routing behavior. When a hub site exists along the
least-cost routing path between source and destination Hub Transport
servers, messages are routed to the hub site for processing before they are relayed to the destination server.
Example 2 provides the syntax and usage, as well as sample output, for the Set-AdSite
cmdlet. To enable a site as a hub site, set the –HubSiteEnabled
parameter to $true. To disable a site as a hub site, set the
–HubSiteEnabled parameter to $false. You must have Enterprise
Administrator rights to use the –Name parameter to change a site's name.
Example 2. Set-AdSite cmdlet syntax and usage
Syntax
Set-AdSite -Identity 'SiteIdentity'
[-HubSiteEnabled <$true | $false>]
[-DomainController 'DCName']
[-Name 'NewSiteName']
Usage
Set-AdSite -Identity 'First-Seattle-Site' -HubSiteEnabled $true
