Defining a Replication StrategyChapter 6 Designing the Replication Process 111One of the more important reasons to replicate directory data is to balance thework load of your network. When possible, you should move data to servers thatcan be accessed using a reasonably fast and reliable network connection. The mostimportant considerations are the speed and reliability of the network connectionbetween your server and your directory users.Directory entries generally average around one KB in size. Therefore, everydirectory lookup adds about one KB to your network load. If your directory usersperform around ten directory lookups per day, then for every directory user youwill see an increased network load of around 10,000 bytes per day. Given a slow,heavily loaded, or unreliable WAN, you may need to replicate your directory treeto a local server.You must carefully consider whether the benefit of locally available data is worththe cost of the increased network load because of replication. For example, if youare replicating an entire directory tree to a remote site, you are potentially adding alarge strain on your network in comparison to the traffic caused by your users’directory lookups. This is especially true if your directory tree is changingfrequently, yet you have only a few users at the remote site performing a fewdirectory lookups per day.For example, consider that your directory tree on average includes in excess of1,000,000 entries and that it is not unusual for about ten percent of those entries tochange every day. If your average directory entry is only one KB in size, this meansyou could be increasing your network load by 100 MB per day. However, if yourremote site has only a few employees, say 100, and they are performing an averageof ten directory lookups a day, then the network load caused by their directoryaccess is only one MB per day.Given the difference in loads caused by replication versus that caused by normaldirectory usage, you may decide that replication for network load-balancingpurposes is not desirable. On the other hand, you may find that the benefits oflocally available directory data far outweigh any considerations you may haveregarding network loads.A good compromise between making data available to local sites withoutoverloading the network is to use scheduled replication. For more information ondata consistency and replication schedules, refer to “Data Consistency,” onpage 99.Example of Network Load BalancingSuppose your enterprise has offices in two cities. Each office has specific subtreesthat they manage as follows:
