• When two servers connect directly -- When a client (in this case, either an IBM® Lotus® Notes® client or an IBM® Lotus® Domino® server) does not share a common protocol with a destination server, you can set up an intermediary server that runs both protocols as a passthru server to enable the client to connect to the destination. For example, suppose that Server A, which runs only NetBIOS, needs to connect to Server C, which runs only TCP/IP. If Server B runs both NetBIOS and TCP/IP, Server B can act as a passthru server to allow communication between Server A and Server C.
• When you want to provide additional security -- Domino lets you apply additional access controls to passthru connections, enabling you to use passthru connections to act as an proxy server for filtering NRPC traffic. You can specify the users and servers that can access a server as a passthru destination, as well as those that can use a server to make passthru connections to another server. Internet protocols such as HTTP, IMAP, and LDAP cannot use a Domino passthru server to communicate with a destination server.

Passthru access is valuable to Notes client users as well. When you provide a Notes client with access a to a passthru server, the client user can connect to a single server to access other network servers. For mobile users, this enables access to multiple destination servers on the same LAN over a single phone connection. Using a passthru server this way saves the time and expense of configuring many individual servers to support modem connections and of requiring Notes client users to use multiple phone calls to access multiple servers.

Passthru Logging

To enable to monitoring of passthru traffic for security reasons, after you configure a server as a passthru server, the server log (LOG.NSF) records information about passthru sessions established through that server. For example, the log records information about users who access this server for to make passthru connections to other servers.

Hunt groups

Note Support for direct dialup modem (X.PC) connections is available only in releases of Domino® earlier than release 8.5. You may continue to use Domino Administrator 8.5 to configure and maintain direct dialup modem support, but only on servers running releases earlier than 8.5.

If your telecommunications infrastructure supports a hunt group -- that is, a pool of modems that are connected to different phone lines but that use a single phone number -- you can configure Domino servers and Notes client users to connect to a hunt group on a passthru server. Whenever a call is made to the hunt group number, the incoming call is routed to the first available modem in the group.

You can use a hunt group with one or more passthru servers. If more than one passthru server is used in the hunt group, to allow any passthru server in the hunt group to receive a call and route it to the destination server, the calling server or user must use a Hunt Group Connection document.

For more information about configuring Lotus Notes clients to use a passthru server, if you have installed Lotus Notes Help, see the topic Passthru servers and hunt groups. Or, visit www.lotus.com/ldd/doc to download or view Lotus Notes Help.

Related topics

Planning server-to-server connections
Setting up a server as a passthru server
Setting up a server as a passthru destination
The Domino server log (LOG.NSF)

Glossary