3Com CoreBuilder 2500 User Manual page 81

IPX packet format
IPX Header (30 bytes)
Packet type = 4
Socket = 452h
Data
Figure 6-5 illustrates the SAP packet structure. Note that the SAP packet
is encapsulated within the IPX packet data area.
SAP packet structure
Operation
Server entry (1)
Server entry (n)
(n <= 7)
Figure 6-5 SAP Packet Structure
A SAP packet consists of the following fields:
Operation — A 2-byte field that indicates the type of operation the
SAP packet performs. You can set this field to one of the following
values:
1=Request
2=Response
3=Get nearest server request
4=Get nearest server response
Server entry — A 64-byte field of server information, which consists
of the following subfields:
Service type — A 2-byte field that identifies the type of service
the server provides
Although IPX routers use SAP, routers typically do not act as servers and
require no Service type assignment.
Server name — A 48-byte name that is assigned to the server.
The server name, in combination with the service type, uniquely
identifies a server on an intranetwork.
Network address — A 4-byte field that contains the server's
network address
Node address — A 6-byte field that contains the server's node
address
(2 bytes)
(64 bytes)
.
.
.
(64 bytes)
Elements of IPX Routing
Server entry structure
Service type (2 bytes)
Server name (48 bytes)
Network address (4 bytes)
Node address (6 bytes)
Socket address (2 bytes)
Hops to server (2 bytes)
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