Layer 3: Network Layer
- Connectionless Network Service (CLNS) – ITU-T Rec. X.213 . SCCP is based on X.213.
- Connectionless Network Protocol (CLNP) – ITU-T Rec. X.233 .
- Connection-Oriented Network Service (CONS) – ITU-T Rec. X.213 .
- Connection-Oriented Network Protocol (X.25) – ITU-T Rec. X.233 . This is the use of the X.25 protocol to provide the CONS.
- Network Fast Byte Protocol – ISO/IEC 14700
- End System to Intermediate System Routing Exchange Protocol (ES-IS) - ISO/IEC 9452 (reprinted in RFC 995).
- Intermediate System to Intermediate System Intra-domain Routing Protocol (IS-IS) - ISO/IEC 10589 (reprinted in RFC 1142), later adapted for the TCP/IP model.
- End System Routing Information Exchange Protocol for use with ISO/IEC 8878 (SNARE) – ITU-T Rec. X.116 .
This level is in charge of transferring data between systems in a network, using network-layer addresses of machines to keep track of destinations and sources. This layer uses routers and switches to manage its traffic (control flow control, error check, routing etc.) So here it takes all routing decisions, it deals with end to end data transmission.
Read more about this topic: OSI Protocols
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