Example: Associating servers through referrals and basic replication

Following are the steps involved in distributing the namespace using referrals.

  1. Plan your namespace hierarchy.
       country - US
       company - IBM, Lotus
       organizationalUnit - IBM Austin, IBM Endicott, IBM HQ
  2. Set up multiple servers, each containing portions of the namespace.
    Figure 1. Setting up the servers
    Setting up the servers

    Following is a description of each server:

    Server A
    Perhaps just a server used to locate other servers in the US. With no other knowledge, clients can come here first to locate information for anyone in the US.
    Server B1
    A hub for all data pertaining to IBM® in the US. Holds all HQ information directly. Holds all knowledge (referrals) of where other IBM data resides.
    Server B2
    A replica of Server B1.
    Server C
    Holds all IBM Austin information.
    Server D
    Holds all IBM Endicott information.
    Server E
    Holds all Lotus® information.
  3. Set up referral entries to point to the descendants in other servers.
    Figure 2. Server A database (LDIF input)
    Server A database (LDIF input)
  4. Servers can also define one or more default referrals that point to more knowledgeable servers for anything that is not underneath them in the namespace.

    The default referrals go in the configuration file, not the backend.

    Note: The default referral LDAP URLs do not include the DN portion.
    Figure 3. Server D configuration file
  5. Putting it all together.

    Figure 4, Figure 5, and Figure 6 show these same six servers, showing the referral entries in the database including the default referrals which are used for superior references. Also included in Servers B1 and B2 are sample definitions for replication, setting up Server B2 as a replica of Server B1. This ensures that these two servers remain identical. Servers B1 and B2 are on the same system, but use different ports.

Figure 4. Referral example summary (servers A and E)
Figure 5. Referral example summary (server B1)
Referral example summary (server B1)
Figure 6. Referral example summary (server B2)