Virtual LAN

VLAN is defined as a virtual local area network. Virtual that means not physically present, but separate logically.
To understand VLAN first we discuss two concepts

1. A Broad cast domain
2. A Collision Domain

What is Domain?

Generally,Domain is a group of devices which share data.Each domain is separated from other domain.  

Broadcast domain  is a logical  division computer network in which all nodes can reach each other by broadcast at data link layer.It might present in the same LAN or it bridge to other LAN.

Collision Domain is a section of the network connected with shared medium where data can collide with one another.

what is VLAN ?

VLAN concept is used in switch because SWITCH divides collision domain, but not broadcast domain. Below the figure is shows working off switch without VLAN.

By default ,all ports on a switch are in the same broadcast domain.
A virtual local area network or VLAN ,can be used to divide a single broadcast domain to multiple broadcast domains in the layer 2 switched network.

What is the need of VLAN ?

1. Performance
In network traffic consist of broadcast and multicast,VLAN can reduce limited that traffic to reach unnecessary destination.

2. Generating virtual group
Now a day people are working in cross functional teams with members of different departments.This people are working together for a particular(limited or short) period of time. Despite of their physical location they belong to one group.

3. Simplified Administration
Maximum cost of computer network is because of adding,movement and changes of users.Some of the tasks are becoming easier.

4. Reduce cost
Due to division of broadcast domain traffic reduce and the need of expensive routers is eliminated.

5. Security
Sensitive data may be broadcast before VLAN. By introducing VLAN that data only access by a group of members who belongs to VLAN.

 Example : In First Figure All nodes belong  to One broadcast domain like in public when a politician is giving a speech and everyone is listening.
In second figure we divide that broadcast domain in to VLAN so now it's like radio broadcast who want to listen to a particular station that can listen only that station.
but in the case of VLAN those who belong to particular VLAN can get that broadcast packet.It increases security because no one else can get that data. 

Routing Protocol and Routed Protocol

Protocol : Protocols are nothing but a set of rules. From childhood we had followed the rules in school,home, etc. This all rules are mandatory for smooth functioning of our daily life, like that the set of rules are mandatory for network communication.

There are two terms used Routing protocol and Routed Protocol.

 What is Routing and Routing Protocol ?

 In computer network routing is a process to find the best path to reach destination network.There are different protocols  available for this purpose like RIP ,EIGRP, OSPF etc. This all protocols are working on a different algorithm.

Routing Protocols are further divided into Interior Routing Protocol and Exterior Routing Protocol

Interior Gateway Routing Protocols : The protocols belongs to this category responsible for routing inside the organisation or we can say that inside one domain. Example of  protocols are RIP, OSPF, EIGRP, IS - IS.

Exterior Gateway Routing Protocols: This type of protocol is used on ISP side or we can say that on the internet to exchange routing information between different autonomous systems.Example of it is BGP .

What is Routed Protocol ?

Routed protocol are responsible to carry the data from one network to another network.Example of this type of protocol is IP , AppleTalk and IPS.

Co-ordinate with Real life Example (Routing and Routed Protocol)

Local Bus Transport: In daily routine local Buses always carry passengers from one stop and drop them at another stop.The Bus route which basically follows is the routing process and imagine the passengers are packets of data carry by bus. So bus itself is a routed protocol responsible to carry data and routing protocol are responsible for finding a path.

Difference between physical address and logical address in networking

Physical Address : 

Physical address is a hardware level address which actually uniquely identify your device at data link layer. This address stored by manufacturer in NIC (Network Interface Card). You can't change this address because it's stored in ROM of NIC card. This address is of 48 bits and divided in to two parts. First 24 bits are assigned for OUI ( Organisationally Unique Identifier ) and last 24 bits identify that device interface.

In this Example first 24 bits that means 0A-00-27 are for OUI and last 24 bits 00-00-15 are for network controller Interface unique identifier.

Logical Address :

Logical Address is also known as IP address.It is changeable. IP address is working at network layer. Logical address is given by two ways.First, Statically and second dynamically. Network administrator or user can assign this address manually to the system.

DHCP ( Dynamic host configuration protocol ) used to assign dynamically IP address to the system. There are different versions of IP addressing.Most popular one is IPv4 which is obsolete and the latest one is IPv6.If you are using IPv4 addressing scheme the it's of 32bits. If you are using IPv6 then it's of 128 bits.

OSI Reference Model

OSI Reference Model

OSI stands for Open Systems Interconnection. OSI model consist of  seven layers.Each and every layer have equal importance.
Physical Layer : This layer is bottom layer.In this layer data in form of bits.Basic functionality of this layer is to  limit data rate i.e bits per second,synchronisation at bit level with other deice,and also concerns with transmission mode (Simplex,half duplex,full duplex).

Data Link layer : This layer co-ordinate with network layer and physical layer.In this layer data in form of frames.Error controlling and handling easy done by this layer.Data link layer address is also know as MAC address or Physical address works on this layer.

Network Layer : The layer co-ordinate with transport layer and data link layer.Data is in form of packet in this layer.The main purpose of this layer is to deliver packet from source to destination using logical address i.e IP address.

Transport Layer : This layer provide assurance  to deliver message  in order as well as error control and flow control using windowing. TCP and UPD are working in transport layer.Transport layer breaks message in segments and gives sequence number.It provides reliable(TCP) and unreliable(UDP) connections.

Session Layer : This layer is use to maintain session among different application.The basic responsibility of this layer is dialog control and synchronisation.

Presentation Layer :  This layer is taking care of syntax and semantics of information exchanged between the different systems.It just represent information is such a ways that the another system can easily understand.

Application Layer : This layer actually work with application and various type of services like email,File transfer ,Directory services provided by it.

Networking Tutorials: Network Basics

Networking Tutorials: Network Basics: Networking Basics A Computer network is a combination of software and hardware.It is intended for smooth work of communication process...

Network Basics

Networking Basics

A Computer network is a combination of software and hardware.It is intended for smooth work of communication process.The basic components of a computer network  are a sender,  medium for communication and receiver.

Topology is a design of a network or pictorial representation of computer network. There are different types of topologies like Bus,Ring,Star,Tree etc.All topologies have their own advantages and disadvantages

Bus Topology

Bus : Bus topology is made up of Backbone cable, nodes and terminators at both the ends.Data travels through the single(Backbone) cable. .Biggest disadvantage is data travel through single backbone if it goes down entire network will go down.Easy to configure and cheaper compare to other topology.Suitable for small networks.

Ring Topology

Ring : All node are arranged in ring and one node is connected with two adjacent nodes.Data travel  through node to node on single path using token in uni-direction.Failure of one node affect entire network.Fault detection is difficult.Performance of ring topology is good compare to bus topology.

Star Topology

Star : All node are connected with center device (Hub or Switch) through cable.Hub handles communication among the node.Compare to bus topology, star topology is more efficient.If one link failed then it's never affect entire topology.Easy to identify faults and easy to modify.It is costlier compare to bus and ring topology.Biggest disadvantage, if hub or switch goes down entire network will do down.