Wide Area Network

Advertisements

WAN Technologies and Cablings

At present, organizations uses different types of WAN technologies and cabling. The choice to use a particular connection standard over another is totally depends on the characteristics and requirements.  Every connection type offers and the advantages it may deliver to user.  Following are the some major WAN technologies:

Frame Relay

It is used for Telco service for delivering blocks of data. It is connection based service and must contract with Telco for circuit between two endpoints. It is typically 56kbps or 1.5Mbps and can run to 100Mbps.

This has been an effective method of communication for many companies over the last 10 to 15 years, but it is gradually being phased out now because of even better communication options.

T1

T1 is a digital carrier signal. It transmits the DS1 signal. It has a data rate of about 1.544 megabits / second and contains twenty four digital channels. These digital connections are called as the CSU (Customer Switching Unit) / DSU (Digital Switching Unit). The scalability of the T1 is up to 200 and above users. Many of the computer uses a T1 connection. This technology makes your modem to have higher speeds and it is an affordable technology.

E1

E1 is similar to the T1. T1 is the North American term whereas the E1 is the European term for the transmission (digital). The data rate of E1 is about 2 megabits per second. It has 32 channels at the speed of 64 Kbps. It is important to know that 2 channels among the 32 are already reserved. One channel is used for signaling while the other channel is used for controlling.

DSL

DSL services are less expensive and primarily used in homes and small businesses. The reason this type of connection can be economical is that the lines it uses are already in place. They are our regular telephone lines. DSL service only works over a limited physical distance and remains unavailable in many areas where the local telephone infrastructure does not support DSL technology.

Several modulation technologies are used by various kinds of DSL, although these are being standardized by the International Telecommunication Union (ITU). Different DSL modem makers are using either Discrete Multitude Technology (DMT) or Carrier-less Amplitude Modulation (CAP). A third technology, known as Multiple Virtual Line.

ATM

ATM was originally developed in the mid-1980s to be used for voice, data, and video applications. We needed a more efficient protocol to provide movies and sound for training and for fun. It uses a fixed-length cell of 53 bytes, rather than the variable-length packets that are used by Ethernet. This allows for more efficiency, since the devices never have to fragment and reassemble large packets. The original ATM technology was already much faster than Ethernet; it was able to transfer voice, data, and video signals at up to 500Mbps. It’s now even faster and is being used by some telecommunication and Internet providers as a backbone or core layer. ATM, like every other technology, will eventually be replaced by faster successors.

SONET

SONET stands for synchronous optical network. It’s especially useful for networks that span multiple geographic regions because the atomic clock mechanism in it keeps everyone on the same exact millisecond. As you can imagine, this protocol requires expensive equipment and expertise. It is typically used by large communication providers and very large corporations as a transfer mechanism or backbone for data traffic

WIRELESS

Wireless WAN is one of the most dynamic technologies of our day. All you really need to know is that a wireless WAN differs from a wireless LAN in that a cell phone service is used to give a person access to the Internet, email, and other online services. It is not the same as the 802.11 technologies used with wireless LAN but instead is something completely different.  UMTS, GPRS, CDMA2000, GSM, CDPD, Mobitex, HSPDA, or 3G are the examples of Wireless WAN technologies.

MPLS

MPLS is similar in nature to Frame Relay and to ATM. It’s similar to Frame Relay in that it is a packet-switching technology that is connection-oriented. It’s similar to ATM in that it is a very organized endpoint-to-endpoint system. It is, however, also very different from either of these, because it does not require fixed-length cells (that have to be rebuilt into packet data later) as does ATM, and it does not have the overhead mechanisms of Frame Relay.

MPLS works by prefixing packets with an MPLS header containing one or more labels, called a label stack. These labels can be detected and managed very quickly within the switch fabric of newer devices. In other words, routers and layer 3 switches can be manufactured specifically to recognize and respond to these labels. This is much faster than using a routing table and the device’s CPU. Routers and layer 3 switches that can perform routing based only on the labels are called label switch routers (LSRs). As you can imagine, these technologies are more expensive than their predecessors, but MPLS will probably eventually replace most ATM and Frame Relay installations.

ISDN

ISDN BRI is a layer 2 protocol that allows for two communication channels and one control channel. The communication channels are referred to as B (bearer) channels, and the control channel is referred to as a D (delta) channel. Each of the B channels can carry up to 64Kbps of data (that used to be a lot), and the control channel can use 16Kbps for data control. ISDN BRI is sometimes referred to as 2B + D, but this is actually misleading because the B channels are really the only usable bandwidth for data. Thus, an ISDN line can carry a whopping 128Kbps of data! In other words, one T1 is the rough equivalent of 12 ISDN BRI lines.

ISDN PRI came out a little later, and it’s a very different story than ISDN BRI. An ISDN PRI link is almost the same as a T1 line in regard to its capacity to carry data. It consists of 23 B channels (each with 64Kbps) and 1 D channel (also with 64Kbps). A little quick math should tell you that a single ISDN link will carry 1,472Kbps, which, as you can see, is very close to a T1.

CISCO ROUTER AND WAN TECHNOLOGIES

Serial transmission is a method of data transmission for long distance communications.  In serial transmission bits of data are transmitted sequentially over a single channel.  However, Parallel transmission transmits the multiple bits at same time.

 serial connectors

Above picture is showing the serial port connectors of CISCO routers.  It uses 60 pin DB-60 connector or the smaller (Smart Serial) connector for WAN connections.  Serial ports on the other end of WAN connection is dependent on the service providers and the type of their DCE equipment include EIA/TIA-232, EIA/TIA-449, V.35, X.21 and EIA-530.

 CISCO routers have different types of interfaces.  Following picture is illustrating the same:

 cisco router

 LAN INTERFACE (ETHERNET AUI, DB-9)

It allow the router to connect with the LAN media through Ethernet, Token Ring or ATM.

 CONSOLE/AUXILIARY (MANAGEMENT PORT)

This port provide a CLI based connection for configuring and managing the device/router.

 WAN INTERFACES (SERIAL, ISDN BRI)

These interfaces allow you to connect to WAN services.

What is Network?

A network can be defined as a system for connecting computers or other electronic devices using a single transmission method/technology. The computers can communicate with each other in a network and can send and receive data from each other.

Network

CLASSIFICATION OF NETWORKS

Computer networks can be classified by its:

  •  SIZE
  • CONNECTIVITY
  • MEDIUM
  •  MOBILITY

Size Aspect

According to size of network, there are two main types:

  •  Local Area Network (LAN)
  • Wide Area Network (WAN)

Connectivity Aspect

According to connectivity, networks can be divided in two topologies:

Point-to-Point

 Point-to-Point topology refers to a communication connection between two nodes or endpoints.  Start and Tree topologies are subtypes of point to point topology.

Broadcast

Broadcasting refers to a method of transferring a message to all recipients simultaneously. Satellite/Radio and Ring topology are examples of broadcast topology.

Medium Aspect

The network classification can also be done on the basis of medium of transmission:

  •  Copper wire
  • Co-axial cable
  • Optical fiber
  • Radio waves

 Mobility Aspect

There are two types of network on the basis mobility aspect:

  • Fixed networks
  • Mobile networks

ADVANTAGE OF NETWORKS IN OUR DAILY LIFE

Networks are used for resource sharing, advertising, production, shipping, planning, billing and accounting purposes.

Networks are very useful at government level as federal government, local government and military organization uses networks for communication purposes.

In education we have online libraries which we can visit at our home PC. This is all just due to the networks.

In addition to this networks are being used in homes as well for example, to switch and control different devices from one place.

Related articles