ZyXEL Communications ISG50 User Manual

Page of 880
 Chapter 48 AAA Server
ISG50 User’s Guide
633
• Directory Service (LDAP/AD) 
LDAP (Lightweight Directory Access Protocol)/AD (Active Directory) is a directory service that is 
both a directory and a protocol for controlling access to a network. The directory consists of a 
database specialized for fast information retrieval and filtering activities. You create and store 
user profile and login information on the external server. 
• RADIUS
RADIUS (Remote Authentication Dial-In User Service) authentication is a popular protocol used 
to authenticate users by means of an external or built-in RADIUS server. RADIUS authentication 
allows you to validate a large number of users from a central location. 
Directory Structure
The directory entries are arranged in a hierarchical order much like a tree structure. Normally, the 
directory structure reflects the geographical or organizational boundaries. The following figure 
shows a basic directory structure branching from countries to organizations to organizational units 
to individuals. 
Figure 422   
Basic Directory Structure 
Distinguished Name (DN) 
A DN uniquely identifies an entry in a directory. A DN consists of attribute-value pairs separated by 
commas. The leftmost attribute is the Relative Distinguished Name (RDN). This provides a unique 
name for entries that have the same “parent DN” (“cn=domain1.com, ou=Sales, o=MyCompany” in 
the following examples). 
cn=domain1.com, ou = Sales, o=MyCompany, c=US
cn=domain1.com, ou = Sales, o=MyCompany, c=JP
Base DN 
A base DN specifies a directory. A base DN usually contains information such as the name of an 
organization, a domain name and/or country. For example, o=MyCompany, c=UK where o means 
organization and c means country. 
Root
US
Japan
Sprint
UPS
NEC
Sales
RD3
QA
CSO
Sales
RD
Countries (c)
Organizations 
Organization Units 
Unique 
Common Name 
(cn)