XNS - Xerox Network Systems (2)
Layer 1 (Network layer) called IDP (Internet Datagram Protocol)
- IDP packet - variable size, 30 - 576 bytes
- address: 32 bits (network number) + 48 bits (host number)
- encapsulation: Ethernet II, Token Ring (3 types)
- support: unicast, multicast, broadcast; routing: RIP
Layer 2 (Transport layer)
- SPP - Sequenced-Packet Protocol (reliable, connection based, flow-controlled; similar to TCP and TP4 (OSI)); packet no longer than 576 bytes
- PEP - Packet Exchange Protocol; functionally similar to UDP
- EP - Error Protocol: notifies client about network errors
Upper layer protocols
- Printing Protocols; Filing Protocols
- Clearinghouse Protocol (name service)
- Courier Protocol - process interaction and data structuring