X.500 products are still new. NET-TEL's active participation in international standards activities and X.500 pilot trials provides the company and its customers with valuable early experience that is reflected in our products.

Standard functions in directory system agents
The Route500 directory system agent, or DSA, stores, queries and retrieves information from an integrated directory database. Each DSA controls a directory database containing information which is locally administered. The data held by the DSA can be completely general in nature, but will usually include information about an organisation's members such as postal and e-mail addresses, telephone numbers etc. The DSA also knows how to connect to and communicate with other DSAs. Information not found on the local database can be retrieved from another DSA. This concept allows global addressing and thereby overcomes the administrative and support problems associated with maintaining multiple copies of directory information within an organisation and the consequent need to synchronise these at regular intervals.

Until X.500 addressing is implemented, an organisation must create a master directory somewhere, keep this updated with all changes to all the local e-mail directories held within that organisation, and distribute a consolidated file containing these changes to each local directory at regular intervals. If carried out properly, a user querying his local directory should always have access to the most current address list covering the whole organisation.

Route500 addressing, on the other hand, allows queries to be routed to more than one DSA. The "home" DSA queried by a Route500 DUA obtains the information needed, when not stored on that DSA, by relaying the corresponding query to either a particular DSA having a high probability of having the information requested, or to all other DSAs in broadcast mode. The inter-DSA communication uses the X.500 directory service protocol (DSP).

Current Route500 DSA implementations exist for several versions of UNIX.

Standard functions in directory user agents
The Route500 directory user agent, or DUA, is normally installed together with a Route400 message client and operates seamlessly with this. This provides directory searching and browsing and is based on an advanced, user-friendly concept. Using standard facilities, users can simply transfer e-mail addressing information from the Route500 or other X.500 server directory to their local address book or, for immediate use, to the recipient address field of outgoing messages. This and other information held in the directories, which can be quite comprehensive, may be transferred into the body part of messages and other general-purpose office documents.

Route500 DUAs are currently available in implementations for PCs and workstations running Windows or Macintosh and can access Route500 DSAs and other vendors' DSAs using the standard X.500 directory access protocol (DAP) over X.25, TCP/IP and asynchronous connections.

Route500 DUA software is integrated with Route400 user agents at several levels and provides a graphical interface with user-friendly naming support. Directory information shown includes not just the usual text containing e-mail and location addresses, phone numbers and fax number, but can also contain an image of the selected person.