The Default Site Link is a 56Kpbs dial-up connection which uses the IP protocol. However, SMTP is recommended for this connection. A schedule will be set on the site link so that replication traffic can only use the WAN link after office hours and when the link is available.
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AD Site links are configured through the AD Sites and Services management console. Expand the Inter-Site Transports folder. The two transport protocols IP and SMTP are displayed, expand the IP protocol to find the Default Site Link. The DEFAULTIPSITELINK is shown, right-click on the link to delete it. Select Delete.
The site-link has now been deleted. Expand the SMTP folder to view its contents. Select New Site Link. Brighton and Birkenhead are both in the Site Link. Specify a name for the link in the Name dialog box. Click OK to continue. The link is now displayed. Right-click on the link to configure its properties. Select Properties.
The Replicate Every box states how often replication will take place, the default is 180 minutes, this can be lowered for more dynamic networks. The link has been assigned a cost of 100. Another link can be created with another cost, if the cost is lower, e.g. 50, then the 50 link will be used first and the 100 link will be used if the 50 link is unavailable. Select Change Schedule to change the replication schedule.
Replication is currently available 24 hours a day, 7 days a week. Set the schedule by selecting the relevant boxes from the schedule window. Replication is now only available between 6pm and 10pm on weekdays. Click OK to continue. Click OK to close the properties box. By default SMTP ignores replication schedules, to change this setting right-click on SMTP. Select Properties. Uncheck the Ignore Schedules box. Click OK to continue. The link has now been created. Remember that SMTP requires the use of certificate services.
Site Link Bridges
Birmingham has a 512k broadband link to Birkenhead. A site link bridge is needed to connect Brighton to Birmingham. The site link bridge will contain 2 links BirkenheadBrighton and BirkenheadBirmingham. There are currently 2 Site links, BirkenheadBirmingham and BirkenheadBrighton. To create a new site-link bridge, right-click on SMTP. Select New Site Link Bridge. The two site links have been automatically selected. Specify a name for the box in the Name dialog box. Click OK to continue. The Site Link Bridge has now been created and is displayed in the management console.
In this diagram all domain controllers will replicate changes with all other domain controller regardless of their location. This can severely reduce the available bandwidth on a WAN link. Only one server in each site should be configured to replicate across WAN links. This server is known as a bridgehead server. Both servers in the Birkenhead site are connected with a high-speed connection. The Birkenhead site however has a slow 56K connection to the other sites. In order to minimize traffic further, one of the servers should be configured as a bridgehead server.
The Birkenhead site currently has two servers. ADMIN1 will need to be configured as a bridgehead server. To configure a bridgehead server right-click on ADMIN1. Select Properties. Add the SMTP protocol into the right-hand box. This server is now the preferred bridgehead server for the SMTP protocol. Click OK to continue. ADMIN1 has now been configured as a bridgehead server for the Birkenhead site.