Computer Networks can be divided into various types depending upon their size and usability. The size of a network can be assessed by its geographical distribution. It can be as small as a room with a few devices/computers or as widespread as across the world, with a million of interconnected devices. Some of the most important types of computer networks are :

• PAN
• LAN
• WAN
• MAN

In this article, we will try to understand WAN in detail.

What is WAN?

WAN is abbreviation for Wide Area Network. WAN is a network that covers a broad area and used to connect end devices like computers and printers which are distributed across long distance. WAN is used to connect different LANs , so it may also be called a network of networks. Internet is essentially a WAN only, that can be regarded as the largest WAN of the world.

History of WAN

WAN was first created by the U.S. Department of Defense. They developed ARPANET i.e. Advanced Research Projects Agency Network, the first ever wide-area packet-switching network with distributed control and the first ever network to implement TCP/IP protocol suite.

Characteristics of WAN

• It provides coverage over a large geographical area with a very broad reach ranging from a state, a country or entire world.
• It needs a public carrier for connection and transmission like a cable system, telephone network, satellites etc.
• It enables the remote access of computers by the users that provides an easier transmission and exchange of data and information.
• It facilitates the centralized storage of data because of remote access.
• WAN is maintained and operated by service providers who exist under distributed ownership.

Drawbacks of WAN

• High cost of initial setup.
• It is vulnerable to attacks and a strong security posture is required for its protection.
• Maintenance is difficult as it requires skilled technicians & network administrators.
• Data transfer speed is lower (upto 100 Mbps).
• High traffic congestion.

WAN Terminology

The various terms of  WAN technology are:

Packet switching:

Packet Switching is a data transmission method, in which data is transmitted in the form of small packets. The message to be transmitted is broken into small parts called packets. Each packet is sent independently over the optimum route and all these packets then reassemble at the destination.

TCP/IP protocol suite:

TCP/IP i.e. Transmission Control Protocol/Internet Protocol is a communication protocol that is used to interconnect the network devices.

Router:

It is a network device that is used to interconnect LANs to form a Wide Area Network.

Overlay network:

Overlay Network is a virtual network that is built top of another network.

PoS (Packet over SONET/SDH):

It determines the communication of point-to-point links while using optical fiber and SONET i.e. Synchronous Optical Network or SDH i.e. Synchronous Digital Hierarchy.

MPLS:

MPLS i.e. Multi Protocol Label Switching (MPLS). It is a technique used for the routing of network packets.

ATM:

ATM i.e. Asynchronous Transfer Mode is a switching technique that uses asynchronous time-division multiplexing to encode data into small, fixed-sized cells. It has largely been superseded by today’s IP-based technologies.

Frame Relay:

It is a technology that is used to transmit data between the LANs in a wide area network. The data is transmitted in the form of frames.

What is SD-WAN?

SD-WAN is Software Defined Wide Area Network. It uses virtualization and software platforms to provide a more efficient data transfer across WAN. It provides easier deployment, operation and management of WAN architecture.

Some of the prominent SD-WAN vendors available in the market are: VMware, Cisco Viptela & Meraki, Silverpeak, Fortinet, Citrix, Aryaka, Huawei and Riverbed SD-WAN.

Continue Reading:

What is Packet Switching?

What is MPLS?

 LAN vs WAN

To understand WAN technology in detail, check our video:

Computer Networks can be divided into various types depending upon their size and usability. The size of a network can be assessed by its geographical distribution. It can be as small as a room with a few devices/computers or as widespread as across the world, with a million of interconnected devices. Some of the most important types of computer networks are :

• PAN
• LAN
• WAN
• MAN

In this article, we will try to understand LAN in detail.

What is LAN?

LAN is abbreviation for Local Area Network. LAN is a network covering a small geographic area and connecting various end devices like computers and printers. LAN is usually limited to a home, office, school or building. Speed is higher (upto 1Gbps / 10 Gbps) and setup is less expensive. The end devices like computers, printers, etc. are connected either with an Ethernet cable to the router or through a wireless router.

In case there are multiple LANs, that can be connected over a telephone line or radio wave. The setup is managed and controlled by each customer itself. LAN is considered pretty secured and easy to manage.

Types of LANs

There are two types of LANs:

• client/server LANs
• peer-to-peer LANs

1.Client/Server LANs:

In this type of LAN, several devices/clients are connected to a central server. This central server is responsible for managing the access to the printer, storage of files and all the traffic through the network. A single device/client can be a PC, a tablet, a laptop or other similar devices capable of running applications. The connect between the central and the devices/clients can be either with ethernet cables or through a wi-fi connection.

2.Peer-to-Peer LANs

In this type of LAN, there is no central server and thus cannot handle heavy workloads. Each PC/device is shared equally in running the network. These devices share all the resources and data and are connected either through a wired or wireless connection to a router. The most prominent example of peer-to-peer LAN is the home network.

Advantages of LAN

The major advantages of using LAN computer networks are :

• Cost effective as it significantly reduces the hardware cost.
• In terms of  software also its economical as there is no need to purchase separate licensed software for each client in the network.
• It offers an increased operational efficiency as all the data is stored in the central server.
• It provides an ease of communication as transferring data over the connected devices is possible in the real time.
• With the advent of wi-fi technology, the spectrum of the type of devices that can be connected in a LAN has broadened.

Disadvantages of LAN

The main disadvantages of LAN are :

• Any discrepancy in the security of centralized data repository can result in unauthorized access of critical data.
• The initial cost of installation of Local Area Networks can be quite high.
• Privacy can be an issue as the LAN administrator has the access to personal data files of every LAN user.
• A constant LAN administration is required to cope up with the issues related to software setup and hardware failures.

Continue Reading:

LAN vs WAN

FAQs Related to LAN:

If you want to learn more about LAN, then check our e-book on LAN Interview Questions and Answers in easy to understand PDF Format explained with relevant Diagrams (where required) for better ease of understanding.

branches in a single logical routed architecture over IP/MPLS network of a Service Provider. This is called Layer 3

VPN generally, but Alcatel-Lucent define this Layer 3 VPN as VPRN(Virtual Private Routed Network).

Different brances of a customer, pass through the IP/MPLS network of Service Provider and this Layer 3 VPN

infrastructure seems to the customer as their branches are connected to a single company Router.

Many different customer networks exist in this IP/MPLS network. And these are managed by Service Provider.

Each of the customer in IP/MPLS network does not know the other network and use the Service Provider managed

IP/MPLS network as their own. This provides indipendence to the customer and efficient usage of network to the

Service Provider.

With VPRN, multiple sites of the customer can connect over the IP/MPLS Network of Service Provider. So, from the

customer perspective, the sites are connected to a Router.

iBGP is abbreviation for Internal Border Gateway Protocol. iBGP protocol is used between the routers within the same autonomous system (AS). iBGP speaking Routers need to form full mesh to maintain full routing information. Full mesh (iBGP neighborship with all Routers in same AS) can be mitigated by using either Route reflectors or BGP confederation.

Key Features of iBGP:

iBGP Neighborship: Both the routers forming iBGP needs to be in the same Autonomous System.

iBGP Advertisement: A route learnt from an iBGP peer will not be advertised back to another iBGP neighbor by default.

iBGP Scope: iBGP is used within the same organisation.

iBGP Administrative Distance: iBGP routes have administrative distance of 200.

iBGP Toplogy: iBGP requires full mesh or else either of route reflectors or BGP confederation.

iBGP TTL: iBGP TTL is set at 255 by default

Continue Reading:

What is eBGP ?

eBGP vs iBGP

In case you are preparing for your next interview, then our cheatsheet on BGP would be really helpful for you as a ready reckoner. Please download BGP CHEATSHEET FREE PDF 

If you want to learn more about MPLS, then check our e-book on BGP Interview Questions and Answers in easy to understand PDF Format explained with relevant Diagrams (where required) for better ease of understanding.

eBGP is abbreviation for External Border Gateway Protocol and is one of the flavors of BGP protocol. eBGP Routing protocol is used between BGP speaking neighbors which belong to different ASNs (Autonomous System Numbers). eBGP functions as the protocol for interconnection of networks from different organizations.

Key Features of eBGP:

eBGP Neighborship: Both the routers forming eBGP neighborship should be in separate Autonomous Systems.

eBGP Route Advertisement: A route learnt from an eBGP peer will be advertised back to another iBGP or  eBGP neighbor by default.

eBGP Scope: It is used between organization, or between organization and ISP(Internet Service Provider).

eBGP Administrative Distance: eBGP routes have administrative distance of 20.

eBGP Topology: It does not require full mesh neighborship.

eBGP TTL: By default eBGP TTL value is 1 which means that neighbors(routers) should be directly connected. When the two neighbors/routers are not directly connected then we can still make it work but we’ll have to use multihop.

Continue Reading:

What is iBGP?

eBGP vs iBGP

In case you are preparing for your next interview, then our cheatsheet on BGP would be really helpful for you as a ready reckoner. Please download BGP CHEATSHEET FREE PDF 

If you want to learn more about MPLS, then check our e-book on BGP Interview Questions and Answers in easy to understand PDF Format explained with relevant Diagrams (where required) for better ease of understanding.