Data Vehicles : 

             The data vehicle which carry's data from source to destination in network. Example :Ethernet, Token Ring, FDDI, ATM, HDLC, PPP, X.25, Frame Relay.

Network transmission

Point To Point (PPP):

         PPP is widely used, especially in the analog modem access to the ISP, where one end is the PC and the other end is the ISP router. The functions performed are:

• The Point-to-Point Protocol (PPP) was designed to transport multi-protocol packets between two peers connected by simple links.
• These links provide full-duplex simultaneous bi-directional operation.
  

Components of PPP: 

          PPP consists of the following three main components: 

• A method  for encapsulating multi-protocol datagrams. PPP supports either asynchronous link with 8 bits of data and no parity, or with bit-oriented synchronous links.
• A Link Control Protocol (LCP) for establishing, configuring, and testing the data-link connection. This allows the two ends to negotiate various link layer options.
• A family of Network Control Protocols (NCPs) 2 for stablishing and configuring different network-layer protocols. This allows the two ends to negotiate various network layer options.

For more about PPP : Click Here.

FrameRelay: 

         Frame relay is a fast packet switching. It has gained widespread support among vendors, users and network providers.           Frame relay can be viewed as a simplified version of X.25. Unlike X.25 which was designed for low speed and high error rate transmission facilities, frame relay is designed for high speed and "error free" transmission facilities. It eliminates a lot of overhead, such as error correction, that is performed by X.25. In stead, it assumes that the end systems will perform those overhead.The frame relay protocol specified by the standards organizations is for the interface between the user and the network only.The mechanism of transporting the frame relay frames inside the network is up to the network provider. The basic bearer service provided by the network is order-preserving transfer of frames from the network side of one user-network interface to the network side of the other user-network interface. The frame is routed through the network on the basis of an attached label. This label is a logical identifier with local significance. 

Specifically, for each connection, the bearer service: 

• provides bi-directional transfer of frames. 
• Preserves the order as given at one user-network interface if and when they are delivered at the other end. 
• Detect transmission, format, and operational errors (e.g., frames of unknown labels).
• Transport the user data contents of a frame transparently. 
• Does not acknowledge frames. 

For more about FrameRelay  : Click Here.

Asynchronous transfer mode(ATM): 

           Asynchronous transfer mode (ATM) is a packet switching transfer mode in which the information is organized into cells. It is asynchronous in the sense that the recurrence of cells containing information from an individual user is not necessarily periodic. ATM is a method of formatting, multiplexing, transporting and switching user information in fixed length (53 bytes) cells. The user information may be voice, data, or video. ATM is a connection-oriented technique. The connection can be set up either using signaling or manually. Signalling and user information are carried on separate ATM layer connections.

For more about ATM  : Click Here.

High Level Data Control:

                   HDLC (High-level Data Link Control) is a group of Protocols or rules for transmitting data between Network points (sometimes called nodes). In HDLC, data is organized into a unit (called a frame) and sent across a network to a destination that verifies its successful arrival. The HDLC protocol also manages the flow or pacing at which data is sent. HDLC is one of the most commonly-used protocols in what is layer 2 of the industry communication reference model called Open Systems Interconnection (OSI). (Layer 1 is the detailed physical level that involves actually generating and receiving the electronic signals. Layer 3 is the higher level that has knowledge about the network, including access to router tables that indicate where to forward or send data. On sending, programming in layer 3 creates a frame that usually contains source and destination network addresses. HDLC (layer 2) encapsulates the layer 3 frame, adding data link control information to a new, larger frame.Now an ISO standard, HDLC is based on IBM's SDLC protocol, which is widely used by IBM's large customer base in Mainframes computer environments. In HDLC, the protocol that is essentially SDLC is known as Normal Response Mode (NRM). In Normal Response Mode, a primary station (usually at the mainframe computer) sends data to secondary stations that may be local or may be at remote locations on dedicated leased lines in what is called a multidrop or multipoint network. (This is not the network we usually think of; it's a nonpublic closed network. In this arrangement, although communication is usually half-duplex.)Variations of HDLC are also used for the public networks that use the X.25 communications protocol and for frame relay, a protocol used in both and wide area network, public and private.In the X.25 version of HDLC, the data frame contains a packet. (An X.25 network is one in which packets of data are moved to their destination along routes determined by network conditions as perceived by routers and reassembled in the right order at the ultimate destination.) The X.25 version of HDLC uses Peer-to-peer communication with both ends able to initiate communication on duplex links. This mode of HDLC is known as Link Access Procedure Balanced (LAPB).

For more about HDLC: Click Here.

Ethernet:

             Ethernet is the most widely-installed local area network ( LAN) technology. Specified in a standard, IEEE 802.3, Ethernet was originally developed by Xerox from an earlier specification called Alohanet (for the Palo Alto Research Center Aloha network) and then developed further by Xerox, DEC, and Intel. An Ethernet LAN typically uses coaxial cable or special grades of twisted pair wires. Ethernet is also used in Wireless LAN. The most commonly installed Ethernet systems are called 10BASE-T and provide transmission speeds up to 10 Mbps. Devices are connected to the cable and compete for access using a Carrier Sense Multiple Access with Collision Detection (CSMA/CD ) protocol.          Fast Ethernet or 100BASE-T provides transmission speeds up to 100 megabits per second and is typically used for LAN backbone systems, supporting workstations with 10BASE-T cards. Gigabit Ethernet provides an even higher level of backbone support at 1000 megabits per second (1 gigabit or 1 billion bits per second). 10-Gigabit Ethernet provides up to 10 billion bits per second.          Ethernet was named by Robert Metcalfe, one of its developers, for the passive substance called "luminiferous (light-transmitting) ether" that was once thought to pervade the universe, carrying light throughout. Ethernet was so- named to describe the way that cabling, also a passive medium, could similarly carry data everywhere throughout the network.

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Token Ring:

            A Token Ring network is a local area network (LAN) in which all computers are connected in a ring or star topology and a bit- or token-passing scheme is used in order to prevent the collision of data between two computers that want to send messages at the same time. The Token Ring protocol is the second most widely-used protocol on local area networks after Ethernet  . The IBM Token Ring protocol led to a standard version, specified as IEEE 802.5. Both protocols are used and are very similar. The IEEE 802.5 Token Ring technology provides for data transfer rates of either 4 or 16 megabits per second. Very briefly, here is how it works:

• Empty information frames are continuously circulated on the ring.
• When a computer has a message to send, it inserts a token in an empty frame (this may consist of simply changing a 0 to a 1 in the token bit part of the frame) and inserts a message and a destination identifier in the frame.
• The frame is then examined by each successive workstation. If the workstation sees that it is the destination for the message, it copies the message from the frame and changes the token back to 0.
• When the frame gets back to the originator, it sees that the token has been changed to 0 and that the message has been copied and received. It removes the message from the frame.
• The frame continues to circulate as an "empty" frame, ready to be taken by a workstation when it has a message to send.

For more about Token Ring: Click Here.

Fiber Distributed Data Interface (FDDI):

                   DDI (Fiber Distributed Data Interface) is a set of ANSI and ISO standards for data transmission on fiber optical lines in a local area network (LAN) that can extend in range up to 200 km (124 miles). The FDDI protocol is based on the token ring protocol. In addition to being large geographically, an FDDI local area network can support thousands of users. FDDI is frequently used on the backbone for a wide area network (WAN).

                      An FDDI network contains two token rings, one for possible backup in case the primary ring fails. The primary ring offers up to 100 Mbps capacity. If the secondary ring is not needed for backup, it can also carry data, extending capacity to 200 Mbps. The single ring can extend the maximum distance; a dual ring can extend 100 km (62 miles).

                         FDDI is a product of American National Standards Committee X3-T9 and conforms to the Open Systems Interconnection (OSI) model of functional layering. It can be used to interconnect LANs using other protocols. FDDI-II is a version of FDDI that adds the capability to add circuit-switched service to the network so that voice signals can also be handled. Work is underway to connect FDDI networks to the developing Synchronous Optical Network (SONET).

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X.25:

The X.25 protocol, adopted as a standard by the Consultative Committee for International Telegraph and Telephone (CCITT), is a commonly-used network protocol. The X.25 protocol allows computers on different public networks (such as CompuServe, Tymnet, or a TCP/IP network) to communicate through an intermediary computer at the network layer level. X.25's protocols correspond closely to the data-link and physical-layer protocols defined in the Open Systems Interconnection (OSI) communication model.

    

For more about X.25: Click Here.