|  | 1.6 | IPX Routing Overview
| 1.6.6 | SAP service advertisements
All the servers on NetWare internetworks can advertise their services and addresses. All versions of NetWare support SAP broadcasts to announce and locate registered network services. Adding, finding, and removing services on the internetwork is dynamic because of SAP advertisements. Each SAP service is an object type identified by a hexadecimal number. Examples:
4 | NetWare file server
7 | Print server
24 | Remote bridge server (router)
All servers and routers keep a complete list of the services available throughout the network in server information tables. Like RIP, SAP also uses an aging mechanism to identify and remove table entries that become invalid. By default, service advertisements occur at 60-second intervals. However, although service advertisements might work well on a LAN, broadcasting services can require too much bandwidth to be acceptable on large internetworks, or in internetworks linked on WAN serial connections. Routers do not forward SAP broadcasts. Instead, each router builds its own SAP table and forwards the SAP table to other routers. By default this occurs every 60 seconds but the router can use access lists to control the SAPs accepted or forwarded.