[. . . ] In the past, finding services on a TCP/IP network was difficult unless an administrator took steps to list available services. With the NSL Manager, network services advertise themselves and applications can find those services. When an application asks it to locate a network service, the NSL Manager uses standard protocols to find available services. [. . . ] On networks that include an SLP Directory Agent (DA), the SLP service agent registers its services with the DA. NSL search requests are then made directly to the DA, reducing network traffic. (Most of this traffic is on the local subnet. ) Advertising and searching hosts must be running compatible versions of the SLP plug-in. Services advertised by version 1. 0 of the plug-in cannot be found by hosts running version 1. 1 or later. Similarly, services advertised by version 1. 1 or later of the plug-in cannot be found by hosts running version 1. 0. To register or discover services outside the local subnet, IP Multicast Router capability must be enabled. Neither MacIP nor PPP support multicasting. SLP Registration in Mac OS 9 When advertising a service, the SLP plug-in in Mac OS 9 follows these steps to decide which network neighborhood (SLP scope) to register the service in: m If the registering application or service specifies a network neighborhood, the SLP plug-in registers the service in that neighborhood. m If no neighborhood is provided by the registering application or service, the SLP plug-in registers the service in the first domain listed in the Search Domains list of the host's TCP/ IP settings. m If no search domain is specified in the host's TCP/IP settings, the plug-in tries to derive a neighborhood from the domain of the service's URL. For example, a service with the URL http://me. mydomain. com is registered in the neighborhood mydomain. com and http://me. sub. mydomain. com is registered in sub. mydomain. com m If none of these steps yields a neighborhood, the plug-in registers the service in the default SLP scope, which is listed as the Local Services neighborhood (or the localized equivalent). 5 SLP Registration in Mac OS 9. 1 and OS X The SLP plug-in in Mac OS 9. 1 and Mac OS X uses a different algorithm from the plug-in in Mac OS 9 to decide which network neighborhood (SLP scope) to register the service in: m If a mandated scope is specified by a Dynamic Host Configuration Protocol server (DHCP SLP service scope option, code 79), the SLP plug-in registers the service in a neighborhood named for that scope. m If the DHCP server does not specify a mandatory scope, the plug-in registers the service in the neighborhood specified in any known configuration or preference file (like the one set using the AppleScript "Set my network neighborhood, " available in the OS 9. 1 online help topic "Sharing a USB Printer"). m If no neighborhood is found in a configuration or preference file, the plug-in registers the service in a neighborhood named for a voluntary scope specified by DHCP. m If none of these steps yields a neighborhood, the plug-in registers the service in the default SLP scope, which is listed as the Local Services neighborhood. Setting Up for LDAP Searches The NSL Manager uses its LDAP plug-in to search LDAP directories for network services. LDAP in Mac OS 9 and Mac OS 9. 1 The NSL Manager's LDAP plug-in always searches the server and associated searchbase specified in the LDAP Services fields in the Hosts settings on the Advanced tab of the Internet control panel. Services discovered in this default directory are listed in a neighborhood that has the same name as the LDAP server. Applications and users can request the plug-in to search additional LDAP directories. Using the Network Browser, for example, you can browse an LDAP directory by adding a neighborhood with the name of the server and the searchbase in this form: <servername>%2f<searchbase> Example: ldap. example. com%2fc=us Note: Choosing an item from the Favorites list in the Network Browser causes all active NSL plug-ins to perform a search. When you choose an LDAP server from the Favorites list, the DNS plug-in may also respond, generating a "nameserver not responding" message. If DNS browsing is not needed, you can disable the DNS plug-in using the Extensions Manager control panel. [. . . ] If you use DNS to list your intranet's services, you control which services clients can discover through NSL searches. However, any network services that utilize SLP registration are discoverable by the NSL Manager. For More Information For more information, see the following sources: Request for Comments (RFC) Documents Service Location Protocol, RFC 2165 Service Location Protocol, Version 2, RFC 2608 DHCP Options for Service Location Protocol, RFC 2610 Lightweight Directory Access Protocol, RFC 1777 Definition of an X. 500 Attribute Type and an Object Class to Hold Uniform Resource Identifiers (URIs), RFC 2079 You can find RFC documents at the following Web address: m www. rfc-editor. org Books and Articles DNS and Bind, 3rd edition, by Paul Albitz and Cricket Liu, O'Reilly & Associates, Inc. 1998 Inside Macintosh: Networking, Chapter 3, "Name Binding Protocol, " viewable at developer. apple. com/techpubs/mac/Networking/Networking-61. html SLP White Paper, at playground. sun. com/srvloc/slp_white_paper. html © 2001 Apple Computer, Inc. [. . . ]