This section provides a sample topology that illustrates an e-mail system for a medium organization with between 1000 and 50,000 mailboxes.The Bravo Corporation is a medium organization composed of 15,000 employees. The organization is divided into functional groups that are geographically distributed in San Francisco, Chicago, and New York City; San Francisco is the headquarters.
Bravo implements the DNS. Its registered domain name is bravo.com and the following are domains that Bravo uses internally to represent each geographic group:
|
|
sf.bravo.com | |
|
|
chi.bravo.com | |
|
|
nyc.bravo.com |
FIGURE B-11 Sample Directory Information Tree for a Medium Organization
The DIT has been partitioned into three subtrees. The partitions are based on the geographic areas that comprise Bravo. One authority manages the San Francisco subtree, another manages the Chicago subtree, and the last one manages the New York City subtree.
Bravo implements the replication feature in its e-mail system. FIGURE B-13 shows how the replicated directory information flows.
FIGURE B-13 Sample Replication Data Flows for a Medium Organization
As shown in FIGURE B-13, master directory servers have been set up on each of the backbone mail servers (one for San Francisco, one for Chicago, and one for New York City). Each master directory server maintains directory information for the sutree below it. Each master directory server also receives a full replication of information from the other master directory servers, meaning that each master directory server also functions as a replica directory server and contains directory information for the entire DIT.Replica directory servers have been set up on each of the departmental mail servers (San Francisco has departmental mail servers for Engineering, Marketing, Corporate, and Manufacturing; Chicago has departmental mail servers for Engineering and Marketing; New York City has departmental mail servers for Engineering and Marketing) for a total of eight. Each of the replica directory servers receives only data pertaining to its functional area or subtree. For example, the San Francisco Engineering replica directory server will receive directory information for the San Francisco Engineering subtree. In this sample topology, replicating partial rather than full information to the replica directory servers will help conserve network bandwidth each time synchronization of information between master and replica directory servers occur.
E-mail System for a Large Organization
This section provides a sample topology that illustrates an e-mail system for a large organization of between 50,000 and 100,000 mailboxes.
For example, Net International Corporation is a large organization with 100,000 employees. The organization is divided into functional groups that are geographically distributed in the United States (offices in Los Angeles, St. Louis, and Boston), Europe (offices in London, Paris, and Rome), and Asia (offices in Tokyo, Beijing, and Taipei).
Net implements the DNS. Its registered domain name is net.com and the following are domains that Net uses internally to represent each geographic and functional group:
Domain Name
Valid Sub Domains
la.net.com
mfg.la.net.com
stlouis.net.com
mfg.tokyo.net.com
FIGURE B-14 Sample Directory Information Trees for a Large Organization
The DIT has been partitioned into nine subtrees based on geographic location, and subsequently into two to four subtrees, based on function. One authority administers each of the geographic and functional subtrees.Net implements one mail server at each of its geographic sites, to form an enterprise for each region. In total, the topology consists of three enterprise servers in U.S, Europe, and Asia. Net also implements one mail server for each of the functional groups at a geographic site as shown in FIGURE B-15.
Net implements the replication feature in its e-mail system. FIGURE B-16 shows how the replicated directory information flows.
FIGURE B-16 Sample Replication Data Flows for a Large Organization
As shown in FIGURE B-16, master directory servers have been set up on each of the backbone mail servers (one for Los Angeles, St. Louis, Boston, London, Paris, Rome, Tokyo, Beijing, and Taipei). Each master directory server maintains directory information for the subtree below it and provides connections via its backbone servers. Each master directory server also receives a full replication of information from the other master directory servers, meaning that each master directory server also functions as a replica directory server and contains directory information for the entire DIT.Replica directory servers have been set up on each of the departmental mail servers, for a total of 24. Each of the replica directory servers receives only data pertaining to its functional area or subtree. For example, the Los Angeles Engineering replica directory server will receive directory information for the Los Angeles Engineering subtree. In this sample topology, replicating partial rather than full data to the replica directory servers will help conserve network bandwidth each time synchronization of information between master and replica directory servers occurs.