IPX Routing

RIP for IPX Packet Structure

The RIP for IPX header (shown in Figure 5.7) comes immediately after the IPX header. RIP for IPX packets have a Packet Type of 0x1 and Source and Destination Socket numbers of 0x453.

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Figure 5.7 The RIP for IPX Packet Structure

Operation The 2-byte Operation field indicates the type of RIP for IPX message. Two values are defined:

0x00-01 - RIP Request is set by a client attempting to find the best route to a destination network (a RIP GetLocalTarget request), or by a router to request all available routes from adjacent routers upon startup (a RIP general request).
0x00-02 - RIP Response is set by a router replying to either a RIP GetLocalTarget or general request. Periodic announcements are also sent as RIP Response messages.

Following the Operation field is one or multiple RIP routes.

For RIP Requests, a single RIP route is included. For the RIP GetLocalTarget request, the single route includes the IPX network number of the desired destination network. For the RIP general request, the IPX network number is set to 0xFF-FF-FF-FF.

For RIP Responses, one or multiple RIP routes are included. For the response to the GetLocalTarget request, a single route is included. For the response to the RIP general request or a periodic announcement, up to 50 IPX routes can be sent in a single RIP for IPX packet. The maximum size for a RIP for IPX packet is 432 bytes. If more than 50 routes need to be sent, they are sent in multiple RIP for IPX packets.

Network Number The 4-byte Network Number field indicates the IPX Network Number.

Hop Count The 2-byte Hop Count field indicates the number of routers that are crossed when using this route.

Tick Count The 2-byte Tick Count field indicates the number of ticks it takes for an IPX packet to be sent using this route.