Network Protocols

A protocol is the special set of rules that end points in a telecommunication connection use when they communicate. Protocols specify interactions between the communicating entities.

Rules of Network Protocol include guidelines that regulate the following characteristics of a network: access method, allowed physical topologies, types of cabling, and speed of data transfer.

Protocols used in networking.

1. Ethernet

The Ethernet protocol is by far the most widely used one. Ethernet uses an access method called CSMA/CD (Carrier Sense Multiple Access/Collision Detection). This is a system where each computer listens to the cable before sending anything through the network.

2. Fast Ethernet

To allow for an increased speed of transmission, the Ethernet protocol has developed a new standard that supports 100 Mbps.

3. Local Talk

Local Talk is a network protocol that was developed by Apple Computer, Inc. for Macintosh computers. The method used by Local Talk is called CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance).

4. Token Ring

The Token Ring protocol was developed by IBM in the mid-1980s. The access method used involves token-passing. In Token Ring, the computers are connected so that the signal travels around the network from one computer to another in a logical ring.

5. FDDI

Fiber Distributed Data Interface (FDDI) is a network protocol that is used primarily to interconnect two or more local area networks, often over large distances. The access method used by FDDI involves token-passing.

6. ATM

Asynchronous Transfer Mode (ATM) is a network protocol that transmits data at a speed of 155 Mbps and higher. ATM works by transmitting all data in small packets of a fixed size; whereas, other protocols transfer variable length packets.

7. Gigabit Ethernet

The latest development in the Ethernet standard is a protocol that has a transmission speed of 1 Gbps. Gigabit Ethernet is primarily used for backbones on a network at this time.

Two-phase locking protocol

A transaction is said to follow the two-phase locking protocol if all locking operations (read_lock, write_lock) precede the first unlock operation in the transaction. Such a transaction can be divided into two phases:

Phase 1: Growing Phase

i)  transaction may obtain locks

ii)  transaction may not release locks

Phase 2: Shrinking Phase

i)  transaction may release locks

ii)  transaction may not obtain locks

If lock conversion is allowed, then upgrading of locks (from read-locked to write-locked) must be done during the expanding phase, and downgrading of locks (from write-locked to read-locked) must be done in the shrinking phase. Hence, a read_lock(X) operation that downgrades an already held write lock on X can appear only in the shrinking phase.

Protocol	Name	Usage
UDP	User Datagram Protocol	UDP is a protocol that provides simple, low-level tools for the transmission and reception of network packets directly to applications. UDP does not control the data transfer and is used mainly for watching or listening to multimedia files on-line.
IP	Internet Protocol	IP is a routable network-level protocol used for unreliable communications of data from one network node to another. The network makes no guarantees about the packet and none, some, or all of the following may apply: data corruption; out of order communications; and/or lost, dropped or discarded communications.
ICMP	Internet Control Message Protocol	ICMP allows Internet nodes to report on errors or submit information on unusual operating conditions.
TCP	Transmission Control Protocol	TCP is the main traffic protocol that ensures reliable delivery of information.
GGP	Gateway to Gateway Protocol	GGP is a protocol two gateways use to interact with each another, specifically in executing control tasks.
ARP	Address Resolution Protocol	ARP is the method for finding a host's hardware address when only its network layer address is known. It is primarily used to translate IP addresses to MAC addresses.
TELNET	Telecommunications Network Protocol	TELNET is a network-level protocol to remotely access a computer by means of a command line interpreter.
Ethernet		Ethernet is a technology for organizing a LAN, where all hosts can receive all messages.
FTP	File Transfer Protocol	FTP is an Internet service for transferring files from one computer to another. It enables connecting to FTP servers, viewing file directories on those servers, uploading files to the server or downloading files from the server, transferring files between servers, etc.
DNS	Domain Name System	DNS is a system that translates human-recognizable domain names and computer hostnames into computer-usable IP addresses (and vice versa) over TCP/IP.
IGMP	Internet Group Management Protocol	IGMP is a communications protocol used to manage a membership of IP multicast groups. It is used by IP hosts and adjacent multicast routers to establish multicast group memberships.
TFTP	Trivial File Transfer Protocol	TFTP is mainly used for the start up of computers that do not have any data storage devices. Unlike FTP, it does not include possibilities for authentication (although IP address filtering is possible) and is based on UDP.
URL	Uniform Resource Locator	URL is used to specify the addresses of almost all network resources.
SNMP	Simple Network Management Protocol	SNMP provides management and control of network devices and applications. Each network agent (device or app) reports through SNMP its status and what factors can be controlled from an administrator’s workstation.
POP3	Post Office Protocol	POP3 is an application layer Internet protocol for retrieving e-mail from a remote server over a TCP/IP connection and is usually used along with SMTP.
DHCP	Dynamic Host Configuration Protocol	DHCP is a network level protocol that enables computer devices to automatically obtain IP addresses and other parameters necessary for working with TCP/IP connections.
HTTP	Hypertext Transfer Protocol	HTTP is an application layer Internet protocol for transmitting mainly web pages (text documents in HTML format) and any images and files connected with those web pages.
PPTP	Point-to-Point Tunneling Protocol	PPTP is a technology that provides very secure Internet communications, which cannot be line tapped.
SMTP	Simple Mail Transfer Protocol	SMTP is a network level protocol for transmitting e-mail messages over a TCP/IP connection.
IMAP	Internet Message Access Protocol	IMAP is an application layer Internet protocol that enables a local client to access e-mail on a remote server. It is used to both send and retrieve e-mail messages.
SSL	Secure Sockets Layer	SSL is a cryptographic protocol, which provides secure communications over the Internet between a client and server.