IPX Packet Format
 

Checksum Indicates that the checksum is not used when this 16-bit field is set to 1s (FFFF). Packet Length Specifies the length, in bytes, of a complete IPX datagram. IPX packets can be any length, up to the media maximum-transmission unit (MTU) size (no packet fragmentation allowed). Transport Control Indicates the number of routers through which the packet has passed. When this value reaches 16, the packet is discarded under the assumption that a routing loop might be occurring. Packet Type Specifies which upper-layer protocol should receive the packet's information. Type codes are: 0 Unknown 1 RIP 2 Echo Packet 3 Error Packet 4 Packet Exchange Packet 5: Sequenced Packet-Exchange (SPX) 16-31 Experimental 17: NetWare Core Protocol (NCP) Destination Network, Destination Node, and Destination Socket  Specify destination information. Source Network, Source Node, and Source Socket Specifies source information. Upper-Layer Data Contains information for upper-layer processes.   Commonly Used IPX Socket Numbers Socket              Service        Description 0451                 NCP             NetWare Core Protocol 0452                 SAP             Service Advertising Protocol 0453                 RIP                Routing Information Protocol 0455                 NetBIOS       NetBIOS over IPX 0456                 Diag.             Packet Server diagnostic packet 0457                Serial #         Check License serial number check betvveen servers 4000-8000      reply               Upper reply socket randomly assigned by client 5100                 Descent        Default for multi-player updates 869C                Id games       Default for doom2, heretic, etc. 26000              Quake            Default for multi-player updates