Communication protocol

In networking, a communications protocol or network protocol is the specification of a set of rules for a particular type of communication.

Different protocols often describe different aspects of a single communication; taken together, these form a protocol stack. The terms "protocol" and "protocol stack" also refer to the software that implements a protocol.

Most recent protocols are assigned by the IETF for internet communications, and the IEEE, or the ISO organizations for other types. The ITU-T handles telecommunications protocols and formats.

Index page for network protocols and protocol layers, categorised by the nearest matching layers of the OSI seven layer model.

Systems engineering principles have been applied to design network protocols.

Protocol Families

Various protocol stacks or families

Individual Protocols

Layer 1 protocols

ISDN Integrated Services Digital Network
PDH Plesiochronous Digital Hierarchy
- T-carrier (T1, T3 etc)
RS-232, a serial line interface originally developed to connect modems and computer terminals
SDH Synchronous Digital Hierarchy
SONET Synchronous Optical NETworking

Layer 2 protocols

ARP Address Resolution Protocol
Ethernet
FDDI Fiber Distributed Data Interface
HDLC High Level Data Link Control
PPP Point-to-point protocol
Token Ring

Layer 2+3 protocols

X.25
Frame relay, a simplified version of X.25
ATM Asynchronous Transfer Mode
MPLS Multi-protocol label switching

Layer 3 protocols

ICMP Internet Control Message Protocol
IP the Internet Protocol itself
- IPv4 Internet Protocol version 4, the current standard
- IPv6 Internet Protocol version 6, in the process of deployment
IPX
Routing protocols:
- Routing between autonomous systems
  - EGP Exterior gateway protocol (obsolete)
  - BGP Border gateway protocol
- Routing within a single Autonomous System
  - EIGRP Enhanced interior gateway routing protocol
  - IGRP Interior gateway routing protocol
  - RIP Routing information protocol
  - OSPF Open shortest path first

Layer 3+4 protocols

Xerox network services (XNS)

Layer 4 protocols

SPX Sequenced Packet Exchange
TCP Transmission Control Protocol
UDP User Datagram Protocol

Layer 5+ protocols

IMAP Internet Message Access Protocol
NFS Network File System

Layer 7 protocols

FTP File Transfer Protocol
HTTP HyperText Transport Protocol, used in the World Wide Web
POP3 Post Office Protocol Version 3
SNMP Simple Network Management Protocol
SMTP Simple Mail Transfer Protocol
Telnet, a remote terminal access protocol
Gnutella, a peer-to-peer file-swapping protocol
DNS Domain Name Service
SSH Secure SHell
IMAP Internet Message Access Protocol
NTP Network Time Protocol
Gopher, a precursor of web search engines
Finger, which gives user profile information
NNTP News Network Transfer Protocol
LDAP Lightweight Directory Access Protocol
DHCP Dynamic Host Configuration Protocol
IRC Internet Relay Chat
WebDAV Web Distributed Authoring and Versioning

and secure versions of the above (as HTTPS, etc.)

Related Items

Protocol Description Languages

ASN.1 Abstract Syntax Notation One