Ipx Service Advertising Protocol - Bay Networks NauticaRS Reference Manual

117237-E Rev.00
Novell IPX uses a 32-bit network address number, followed by
the 48-bit node number (usually the MAC address), followed by
the 16-bit socket number.

IPX Service Advertising Protocol

IPX routers collect Service Advertising Protocol (SAP)
information from servers on the Novell network. This SAP
information is broadcast every 60 seconds to all directly
connected networks, to allow clients to find out the location of
those services provided by the servers on the network.
The protocol defines several functions to be performed with its
SAP packet:
• A workstation request for location of nearest server
• A special request by a router for either all the servers on the
given network, or all of the routers of a particular type on a
given network
• A response from any of the above
• A periodic broadcast by either a server or a router
• A changed server information broadcast
The Service Information Table is used by all routers to track SAP
information that is sent out by Novell servers. Typically this
contains information about the server's address, its name, its type,
the number of hops away from the router, the interface card that
the router would use to get to the server and the aging timer used
to maintain valid server information.
When a router becomes active on a Novell network, it starts to
listen to all SAP broadcasts. The server information is then added
to the router's server information table, so that the router can send
SAP broadcasts to each attached Novell network.
Introduction to Protocols and Routing
1-17