Information Technology Reference
In-Depth Information
You might need to designate bridgehead servers manually sometimes. Perhaps you've iden-
tified a DC in a site that's less burdened by other server tasks and is better able to handle the
task than the server identified by the ISTG. You can use the repadmin /bridgeheads command to
list which DCs in a site are acting as bridgehead servers to other sites.
After you have determined which DCs are currently acting as bridgehead servers, you can
designate preferred bridgehead servers in Active Directory Sites and Services. Find the server in
the Servers folder under the site, right-click the server object, and click Properties. Select the
intersite transport protocol on the left (see Figure 10-25), and add it to the “The server is a pre-
ferred bridgehead server for the following transports” list box. You need to make sure all direc-
tory partitions in the site are contained on the bridgehead servers you configure. If you don't,
Windows warns you about which partitions the configured bridgehead servers won't replicate.
Replication still takes place for these partitions because Windows configures the necessary
bridgehead servers automatically, but relying on this automatic configuration defeats the purpose
of assigning bridgehead servers manually.
Figure 10-25
Configuring a bridgehead server
If a manually configured bridgehead server fails, replication for the parti-
tions it contains stops. The ISTG doesn't configure a new bridgehead
server automatically for a failed manually configured one. However, if the
ISTG assigns the bridgehead server and it fails, the ISTG automatically
attempts to assign a new one.
Intersite Transport Protocols
Two protocols can be used to replicate between sites: IP
and SMTP. By default, IP is used in the DEFAULTIPSITELINK site link and is recommended in
most cases. To be precise, when you choose IP as the intersite transport protocol, you're choos-
ing Remote Procedure Call (RPC) over IP. RPC over IP uses synchronous communication, which
requires a reliable network connection with low latency. With synchronous communication,
when a request is made, a reply is expected immediately, and the entire process of replication
with one DC finishes before the process can begin with another DC.
If your network connections don't lend themselves to RPC over IP, you can use Simple Mail
Transport Protocol (SMTP). SMTP, used primarily for e-mail, is an asynchronous protocol that
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