WAN network

Wide Area Network (WAN) is a network that is used to make local interconnection of computer networks that are not physically adjacent to each other, which can be physically separated from the city, province, or even across the border geography - across countries and continents. There are several current WAN Network Technology that we can use. Unlike a LAN, there are major differences between the two which is the distance separating two networks are connected. WAN using different transmission media, as well as hardware and a different protocol to the LAN. Data transfer rate in WAN communication is generally much lower than the LAN.
Communication Networks WAN
WAN Network Technology relies on third parties in this case are Telecommunication service provider company providing long-distance relationship. Unlike the LAN network where connections between devices (computers) are transmitted from one digital device / computer to other digital devices through a direct physical connection, WAN technology uses a combination of analog signals and digital signals to transmit data.
In the WAN network diagram below describes each two components and functions in WAN network technology concept.Diagram WAN network connections
Fig 1 Diagram WAN connection

    DTE (Data terminal equipment) is a hand tool WAN link that is on the customer side (usually the building / home customers) that send and receive data. DTE (usually a network router or should it be a computer or multiplexer) is a sign marking the WAN and LAN networks. DTE is a device that will communicate with the other side of the DCE devices.
    Demarc or demarcation point is the point where the cable is a network interface connected to the telephone company's customers.
    Local Loops is an extension cord from the telephone line Demarc leading Telco central office where maintenance difihak Telco, not the customer's responsibility. This cable can be UTP cable, fiber optic or a combination of both as well as other media.
    DCE (data circuit terminating equipment) is a device (usually a router side ISP) that communicates with the DTE and the WAN cloud. DCE is a device that supplies clocking (pulse synchronization signal) to the DTE device. A modem or CSU / DSU at the customer could be classified as a DCE. DTE and DCE can be beupa similar device / router but have different roles and functions.
    WAN cloud, is hirarchi Trunk, Switches, and the CO (central office) that form a network of telephone lines. The physical structure may vary, and different network-2 with common connection points may overlap, hence represented in the form of WAN cloud. Sides of importance is that the data entered via the telephone network, exploring along the line phone, and arrives at the right destination address.
    PSE (packet switching exchange) is a switch on the carrier packet switched network. PSE-2 is the connecting points of the WAN cloud.
Package messages roam from point to point are different depending on the physical connection and the protocol used. Here is no longer discussed the technology in the WAN network WAN connections that have been discussed before, that there are three basic kinds of the following:

    Dedicated Connection
    Circuit-switched networks
    Packet-switched networks
Type dedicated and switched WAN networks have a connection that is always available to the network, but for this type of circuit switched need to do some sort of connection establishment via dial-up mechanism between the two devices that want to communicate. In a configuration of dial-on-demand routing (DDR) - the router automatically open the connection if there is data to be ditrasnmisikan (of course in accordance with the access-list rule), and it will close itself if the line is idle for a specified duration set in the configuration .
WAN Network Services
There are many applications on the WAN network technology WAN services by an ISP or WAN connection services are as follows:
PSTN
PSTN is the public switched telephone network, it is the oldest technology and is widely diapakai worldwide over a WAN communications. PSTN is a WAN network technology in circuit-switched networks. This technology-based dial-up or leased line (always-on) use a telephone line where data from digital (computer) is converted into analog data by modem, and then the data is limited to cruise at up to 56 Kbps only.
Leased lines
Dedicated leased line is a type of WAN technology uses a permanent direct connection between the devices to communicate and provide a constant connection with the quality of the connection service (QoS). However, leased lines are more expensive than the connection as needed (dial-on-demand) PSTN.
X.25
X.25 specified by ITU-T - is a WAN packet switching network technology over PSTN networks. X.25 is built with reference to the Data Link Layer and Physical Layer of the OSI reference model. Originally X.25 using analog line to form a packet switched network, although X.25 can also be formed using a digital network. X.25 protocol defines how connections between DTE and DCE in the setup and maintained in the Public Data Network (PDN)

    You need a subscription X.25 can use a dedicated line to the PDN to form a WAN connection.
    X.25 can operate at speeds up to 64 Kbps on the analog line.
    X.25 using the frame as a variable packet size
    Supplied error detection and correction to ensure reliability through low quality analog line.
Frame relay
Frame relay has been discussed at length separately, the article includes a frame relay network and frame relay connections. Frame relay is a WAN technology in packet switching networks - WAN via a communication line of high-quality digital.
ISDN
ISDN is also discussed in detail separately, see here for ISDN BRI and ISDN PRI ISDN networks. ISDN (Integrated services digital network) defines standards on the use of a telephone line for both analog and digital transmissions.
ATM
Asynchronous Transfer Mode (ATM) network is a WAN technology with high-speed connections using a packet switched system from a speed of 155 Mbps to 622 Mbps. He can transmit data simultaneously, which digitize voice and digitize video signals through both LAN and WAN networks. ATM includes the following characteristics:

    Using a small fixed-size cells (53-byte) which is processed younger than X.25 and frame relay using the cell length bervariable
    Transfer rate can be as high as up to 1.2 Gigabits
    Digital line of high quality, low noise, which eliminates the need for error-checking.
    Can use a variety of media both coaxial, twisted pair, or fiber optic.
    Can simultaneously transmit different types of data.
There is no clear distinction between WAN services such as frame relay and ISDN. Let's say you can use frame relay protocol over ISDN line. Once the device is connected to the WAN cloud, internal protocol data traffic can convert into the necessary format and then convert the data back the other side.
Hardware WAN
Hardware WAN WAN usually depends on the service you want to connect. Each WAN protocol has different specifications and requirements for hardware and transmission media. However, you have a choice in the hardware you use, and always compatible with the hardware WAN WAN services.
WAN service providers usually give you the choice of what hardware will be used for the WAN network and local loop to the demarc point. Local loop usually copper cable, the same cable used for telephone service.
Copper cables are classified based on bandwidth, in turn determines how much data can be sent, and if the signal is analog or digital. The following are two methods of classifying bandwidth over copper.
POTS (plaint old telephone services)
POTS service has the following characteristics:

    Cables are available only using a single twisted pair
    Analog signals used by local loops
    A modem is required to be used to convert digital signals into analog signals.
    Effective boundary line limited to 56 Kbps
T-Carriers
WAN network technologies using the technology T-Carriers have the following characteristics:

    Using two pairs of twisted copper wires
    Using a digital signal
    Some 64 Kbps channel operates on the same cable.
T-cariers line classified by multiple channel support, namely:

    T1 (24 channels)
    E1 (31 channels)
Note that the 64 Kbps channel is sometimes referred to as DS-0. Line that uses 24 channels (T-1) is also commonly referred to DS-1 line. Line T-Carriers can be divided according to the type of data (ie, data, digitized voice, video digitized).
In addition to the transmission media, you need to connect to the WAN hardware and signal format appropriate for the type of connection you use. We know that the modem converts analog signals to digital and vice versa. We use one or both of the following hardware in all digital networks:
Multiplexer
A multiplexer is the hardware that combines signals from two or more media devices into the same segment. On the receiver side, the signal-multiplexer separates the two combined.

    A Statistical multiplexer using different virtual channel2 on the same physical medium to transmit several different sinyal2 once, namely sinyal2 crawl along the same medium
    Time-division multiplexers to send data packets from different sinyal2 at different time intervals rather than having to send the package by dividing a physical medium into chanel2, data is sent at a different time slot.
CSU / DSU
A channel service unit / data service unit (CSU / DSU) to connect a network with high-speed line such as T1. This tool to format a digital data stream into the proper frame format and line code for digital line. It also provides functions timing. Some CSU / DSU also serves as a multiplexer also integral or built into the router.

    CSU receives and sends signals to the WAN line, do echo feedback signal during test calls and reduce electrical interference
    DSU like a modem between DTE and CSU. He converts frames of the format used in the LAN into the format used on the T1 line, and vice versa. He is also managing the line, timing errors and signal regeneration.
We can also use a wide range of interface protocol for WAN connectivity, such as synchronous or asynchronous serial protocols protocols.
Synchronous serial protocol uses a stable clock signal between the DCE and the DTE to the data transmission time. Synchronous communications to send large data frame with time clock and baud-rate. It uses bandwidth efficiently.
Protocol synchronous signals include:

    V.35
    RS-232 (EIA / TIA)
    X.21
    RS-449
    RS-530
Each type of serial device using special konekstor include:

    DB60
    DB25
    DB15
    DB9
Note that the number that follows indicates the number of pins, showing the amount of DB25 pin 25 and so on.
Asynchronous protocol
Protocol-bit asynchronous adds start and stop-bits in each packet sent instead of forcing both the sending and receiving devices to use the same clock. Signal asynchronous protocol is most widely used between the two modems. But he also adds overhead because of the addition of extra bits which in turn slows down the baud rate. Asynchronous signaling protocols include:

    V.90
    V.42
    V.35
    V.34
    V.32, V.32bits, V.32turbo
    V.22
Asynchronous signals using a standard telephone line and jacks. Connections include:

    RJ-11 (2 wires)
    RJ-45 (4 wires)
    RJ-48
Interface can be referred to a physical port on the router that connects the LAN and WAN.
The method of encapsulation WAN network
WAN physical layer protocol specifies the method of hardware and signal bits. Data link layer protocol to control some or all of the following fungsi2:

    Error checking and correction
    The establishment of a link
    The composition of the frame-field
    Point-to-point flow control
Protocol2 Data link layer encapsulation method or also describes the frame format. WAN encapsulation method is generally HDLC (high-level data link control). Depending on the service and the WAN connection method, multiple encapsulation methods include:

    Cisco HDLC for synchronous, connection point-to-point with a Cisco router
    Jaringan2 for X.25 LAPB
    LAPD protocol in combination with other B channel in ISDN networks
    PPP for dial-up access to the LAN, WAN networks and circuit-switched ISDN network
    Cisco / IETF for frame relay networks
WAN encapsulation - WAN protocols
Fig 2 WAN encapsulation
The diagram above describes the encapsulation method different WAN technologies. Want to know more detail and complete all the basic concepts of WAN, from a WAN connection, the WAN through static and dynamic routing, from the distance vector to link state routing - Kllik here tutorial e-book full of computer networks.