In this article, we will learn about the virtual Router, its key features, use cases, and the future of this virtual routing solution in modern networks.

Introduction to Virtual Router

A vRouter, also known as a virtual router, is a software-based router that runs on a virtual machine (VM). It performs the same functions as a physical router i.e.

• routing traffic between networks, 
• forwarding packets, and 
• implementing networking protocols such as TCP/IP, OSPF, and BGP. 

A vRouter can run on any hypervisor, including VMware, KVM, and Hyper-V. It can be deployed in a variety of environments, such as public and private clouds, data centers, and branch offices. A vRouter can also be used in conjunction with physical routers to create a hybrid network topology, allowing for seamless integration between virtual and physical environments.

Features of vRouter

Flexibility & scalability

A vRouter has the flexibility to be deployed in a variety of environments, from public cloud to data center to branch office. It can also be scaled horizontally to handle increasing amounts of traffic..

Cost-effectiveness

By eliminating the need for dedicated hardware, a vRouter can significantly reduce the cost of networking infrastructure. This is especially true in virtualized environments, where the cost of physical hardware can quickly add up.

Integration with virtualization platforms

A vRouter can be seamlessly integrated with virtualization platforms such as VMware and KVM, allowing for easy deployment and management.

Security

A vRouter can be configured with advanced security features such as firewalling, VPN, and intrusion prevention, providing a secure environment for network traffic.

Virtual Router vs Physical Router

While a vRouter and a physical router perform the same functions, there are some key differences between the two:

Hardware requirements

A physical router requires dedicated hardware, such as a router chassis and network interface cards (NICs), while a vRouter can run on any hypervisor without the need for specialized hardware.

Scalability

A physical router has limited scalability, as it is constrained by the number of NICs and processing power available. A vRouter, on the other hand, can be scaled horizontally to handle increasing amounts of traffic.

Cost

A physical router can be expensive, especially in high-performance environments where multiple routers are needed. A vRouter is typically more cost-effective, as it can be deployed on commodity hardware and does not require specialized components.

Use cases for vRouters

There are several use cases for vRouters:

Public & Private Cloud Environments

In public and private cloud environments, a vRouter can be used to route traffic between VMs and the outside world. It can also be used to create virtual networks within the cloud environment, providing a secure and isolated environment for applications and services.

Data center environments

vRouter can be used to route traffic between servers and storage devices, as well as between different data center locations allowing for easy segmentation and management of network traffic.

Branch office environments

vRouter can also be used to connect remote offices to the corporate network, providing secure and efficient communication between geographically dispersed locations.

vRouter: Installation & Configuration

Choose a hypervisor and download the vRouter software. 

The vRouter can then be deployed as a virtual machine on the hypervisor.

Once the vRouter is deployed configure it  with network addresses, routing tables, and other networking parameters using the vRouter’s web-based management interface/CLI.

vRouter: Common Troubleshooting Issues

Connectivity issues

It may be due to misconfigured network settings or a problem with the physical network adapter. Check vRouter’s network settings & verify connectivity to the physical network.

Performance issues

It may be due to insufficient resources or misconfigured networking parameters. Check vRouter’s resource utilization and review its configuration settings.

Security issues

It may be due to misconfigured firewall rules/outdated security software. Review  vRouter’s security configuration and update its security software as needed.

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Difference between Network Bridge and Router

Common Types of Attacks on Routers

In this article we will learn more about Low power wide area network standard, its features, advantages, and limitations.

Low Power Wide Area Network (LPWAN)

Low-power wide-area network (LPWAN) are specifically created for M2M and IoT devices – it enables low power usage, long range wireless connectivity. It is emerged in 2013 and it is a generic term which refers a class network technologies which are designed to communicate without wires over relatively long distances using less power than any other conventional networks such as Wi-FI, satellite etc. Energy efficient and wider coverage is the two main characteristics of LPWAN. In IoT devices growth and increasing penetration which is expected to grow to 22 million in 2025, LPWANs will be key drivers in this growth.

Types of LPWAN technologies

Non-Cellular LPWA Networks –

Network based LPWA solutions such as Sigfox or LoRa use the existing cellular technologies to provide the services, such as LTE-M and NB-IoT.  French start up created LoRaWAN which specialize in transmission of data packets between 0.3 and 50 Kbits per second (Kbps) and was acquired by Semtech, founder of the LoRa Alliance. It is an open source network that can be developed or operated by any company with only limitation of purchasing LoRa chips.

It ensures transferability between operators and benefit from roaming agreements between alliance members. Sigfox is LoRaWAN competitor, created in 2009 as a French initiative in the field of IoT technologies. Low speed networks require the use of Sigfox – certified transmitters and receivers and guarantees compatibility and facilities interpretability between all countries. (Covered).

Standardized Cellular LPWA Networks –

The 3GPP organization proposed two standards for IoT based one existing cellular network. LTE-M and NB-IoT to alleviate the issues of compatibility of M2M applications and reduction in production costs of communication modules. LTE-M technology offers more stable speed, reduced latency and better roaming capabilities as compared to its non-cellular rivals. LTE-M offers higher speeds of up to 1 Mb/s.

NB-Iot is a standard choice for telecommunication giants it uses 200 KHz frequency band and ideal for applications such as telemetry and large number of fixed assets in the field which require reduced data volumes where speed of transmission is not of primary importance.

Applications of Low Power Wide Area Network (LPWAN)

LPWAN networks offer multiple possibilities and can be used in diverse areas. We will look at some use cases which are already defined and already being tested and implemented in real life scenarios lets look at them.

Parking management –

LPWAN offers flexible solution to address parking management in city areas, IoT sensor identifies whether parking space is vacant or occupied and this information is used as an input for applications such as signs indicating how much parking space is vacant or available, where sites are located and any vehicle parked for too long. Use of low power LPWA is an ideal solution as its low power feature will save costs of changing all batteries of hundreds of parking space monitors.

Public and lighting infrastructure –

Multiple light bulbs installed on roads, sidewalks, crowded places, or lonely highway stretches and tracking which bulb went off and informing the authorities, LPWA could alert command center if light bulb is working or off.

Water and Pipe meters –

A pressure gauge communicating data readings to help to identify a leakage as pipelines run miles and ability to communicate over long distances where no network exists LPWA can be used in such underground penetration allowing monitoring of pipelines.

Small pallets –

While tracking shipments load is scanned and LPWA makes it possible to implement smart pallets to track movement of cargo and track if it is opened, dropped, or mishandled.

Pros and Cons of Low Power Wide Area Network (LPWAN)

PROS

• Low power consumption which enables devices to last up to 10 years on a single charge
• Optimized data transfer which supports small , intermittent blocks of data
• Low device unit cost
• Less number of base stations to provide coverage
• Easy network installation
• Dedicated network authentication
• Optimized for low throughout long or short distanced
• Enough indoor penetration and coverage
• Enhance security when LPWAN deployed in licensed spectrum
• Offers longer ranges from 5 KM to 30 KM
• High amount of penetration through walls and building basements
• Secured communication between nodes and gateways with encryption algorithms

CONS

• Supports low data rate hence not suitable for high data rate applications
• Offers high latency between end to end nodes so not ideal for low latency applications

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What is WAN? Detailed Explanation

M2M vs IOT

Today we look more in detail about two most popular and widely used reference models – OSI and TCP/IP, their features, functions and use cases.

About TCP/IP model

TCP stands for Transmission Control Program and IP stands for Internet protocol. TCP/IP model has a layered architecture and has four layers. The TCP/IP model is protocol-oriented standard. This model was developed by the Department of Defence (DOD) project agency. Internet protocols are a set of rules defined for communication over the network. TCP/IP is considered the standard model for networking and handles data transmission and IP handles addresses. The TCP/IP suite includes protocols such as TCP, UDP, ARP, DNS, HTTP, ICMP etc.

TCP/IP Model Features

• Multi-vendor support is available
• Used for around 35 years and most widely used protocol
• It supports interoperability
• It supports logical addressing
• It has routability feature
• It has name resolution feature
• Error control and flow control are supported features

About OSI Model

The OSI stands for Open System Interconnection, developed in the 1980s by the International standard organization.  It is a conceptual model used in network communication. The OSI model consists of seven layers and each layer is connected to each other. The data moves through the OSI model from its start till end (Last layer of OSI model).

OSI Model Features 

• Model to demonstrate how hardware and software work together
• Ease of troubleshooting (Each layer detects and handles error) 
• Reduction in complexity
• Standardization of interfaces
• Facilitates modular engineering
• Provides interoperability between vendors 

The application layer of the TCP/IP model maps to the first three layers i.e., Application, Presentation & Session Layer of the OSI model. The transport layer maps directly to the transport layer of the OSI model. The Internet layer maps to the Network layer of the OSI model. The last two layers of the OSI model map to the Data link layer and physical layer of OSI model. TCP/IP model is more widely used as compared to OSI model. 

Similarities between TCP/IP and OSI Model

Common Architecture – both models are logical and have similar architecture based on layered approach.

Defined Standards – both models define the standard and framework for implementing the standards and devices. 

Troubleshooting is simplified – by breaking complex functions at each layer into simple components.

Pre-defined standard – the protocols and standards are already pre-defined; and models do not redefine them, it just references it or uses it. Like Ethernet standards were already defined by IEEE before the origin of this model and it uses this in its reference at Physical layer or Network access layer.

Similar functionality at transport and network layer – function performed between presentation and network layer is similar to the function performed at transport layer.

Comparison Table: TCP/IP MODEL vs OSI MODEL

Below table summarizes the differences between the two:

FUNCTION	TCP/IP MODEL	OSI MODEL
Definition	TCP/IP stands for Transmission control protocol/ Internet protocol	OSI stands for Open systems Interconnection
Developed by	It is developed by DOD (Department of Defence) project agency.	OSI model is developed by ISO (International standard organization).
Technology/ Platform	It comprises of a set of standard protocols which lead to development of the Internet. It is a communication medium which provides connection between hosts.	It is an independent standard and generic protocol used as a communication gateway between network and end user.
Delivery of Packets	No guaranteed delivery of packets at transport layer.	Transport layer provides guaranteed delivery of packets.
Approach	Based on horizontal approach.	Based on vertical approach.
Application Layer	Session and presentation layers are not separate, both are included in application layer.	Session and presentation layers are separate
Type of  Model	Implemented model of OSI model.	It is a reference model on which various networks are built.
Network layer	Network layer provides only connectionless service.	Network layer provides connection oriented and connection less services (Both)
Replaceable/ Non-replaceable Protocols	Protocols can’t be easily replaceable	In OSI model protocols are hidden and can be easily replaceable when technology changes occur
Number of Layers	Comprises of four layers	It comprises of seven layers
Protocol Dependent/Independent	Services, protocols, and interfaces are not properly segregated but are protocol dependent	Services, protocols and interfaces are defined and it is protocol independent
Usage	Widely used model	Limited usage of the model
Standardization of devices	Do not provide standardization of devices	Standardization of devices like router, switches, load balancers and other hardware devices

Download the Comparison Table: TCP/IP MODEL vs OSI MODEL

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OSI Model – The 7 Layers

Introduction to TCP/IP

The Transmission Control Protocol/Internet Protocol (TCP/IP) is a network communication protocol that interconnects the network devices into the internet. It provides a communication between the source and the destination. It specifies how data packets should be broken, addressed, routed, transmitted, and the status to be received at the destination. TCP deals with the delivery of data and how the data packets applications can create their route across the network. It also manages the message into smaller packets before transmission. The IP section deals with obtaining the address of the data and the path a package will use.

The layers of TCP/IP

How TCP/IP works

It uses the client-server communication model. A client provides the service by a central server. The suite protocol is stateless, thus enabling them to free up the network paths to be used continuously. This model of communication is divided into four main layers. Each layer has a set of functions and protocol used for communication.

Protocol in the TCP/IP

Layers of TCP/IP model

The layers of TCP/IP model are explained below:

The application layer

It’s the topmost layer at the TCP/IP model. It defies the internet services standard and network applications to be used by the user. It states the application protocol and how the host application and programs interface with the transport layer in the network. It provides a channel for standardization of data exchange. Its contracts include:

1. Domain Name Server: it works by resolving the IP address into a textual format for the hosts.
2. File transfer protocol: Allows the transfer of files amongst the user in a network
3. Telnet: Manages the connection of remote machine and runs applications
4. Simple Mail Transport Protocol: It transport electronic mail between the sources and destination through a route.

Transport layer

Its main goal is to maintain an end to end communication between the source and destination across the network. It manages the interaction between the sources and provides multiplexing, flow control and reliability of data. The transport protocols include

1. Transmission Control Protocol: It’s a connection-oriented protocol that communication in bytes foam from the source to destination without the flow control and error messaging.
2. User Datagram Protocol: It’s a connection-less protocol that is unreliable. It does not verify the connection between the source and the destination. It doesn’t establish and check the links.

Network layer

It works by controlling movement of data packets across the network. It accepts and delivers the packets across the web. It deals with providing the packets. Routing and congestion avoidance. It packages the data into IP datagrams which contain the address of the source and destination. It allows the host to insert the packets into any network and deliver them independently. The main protocols here include

1. IP protocol: It deals with IP addressing, packet formatting, fragmentation and host to host communication.
2. ARP Protocol: The address Resolution Protocol assists the IP in directing the datagrams to the correct hist. It maps the Ethernet address.
3. ICMP Protocol: The internet control message Protocol helps to detect and control the network errors. It works by either redirection, dropping the packet or connectivity failure.

Datalink layer

This layered work by identification of the network protocol type to use for the packet. It also provides error control and packet framing. It handles the physical section of sending and receiving data over the Ethernet cable, wireless or the network interface card. Some of the protocol used include Ethernet, Token Ring and Point to Point Protocol framing (PPP).

TCP/IP is nonproprietary and compatible with all operating systems. It’s highly scalable and the mostly used over the internet.

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UDP Header

When does DNS use TCP or UDP?

MPLS i.e. Multi Protocol Label Switching (MPLS). It is a technique that is used for the routing of network packets. It is called a  Multiprotocol as it supports multiple protocols like Internet Protocol (IP), Asynchronous Transport Mode (ATM) and Frame Relay protocols. Moreover, in MPLS technique the network packet forwarding is done based on the label present on the packet, that’s why it is called Label Switching.

MPLS : The “Shim” Protocol

As we know that there are 5 layers of TCP/IP Model. The MPLS layer lies between the layer 2 i.e. the Ethernet layer and the layer 3 i.e. Network layer of the TCP/IP model. So, in other words, it shims(fill up the space) between two layers and hence also known as the “shim” protocol.

MPLS Header

The MPLS Header consists of 32 bits. It consists of –

1. Label: It consists of 20 bits, so the label can take values from 0 to 2^20–1, or 1,048,575. But the first 16 label values(0 to 15) are exempted from normal use as they have a special meaning.
2. Experimental(Exp): It consists of 3 bits. These are used for Quality of Service.
3. Bottom of Stack(BoS):  There can be more than one MPLS labels for a network packet. These labels are stacked one over another. Bottom of Stack field is of 1 bit and it ensures which MPLS label is at the bottom of stack. The bit value is 1 or high only when that particular label is at the bottom of the stack otherwise its value remains 0.
4. Time to Live(TTL): It consists of last 8 bits. Its function is similar to the TTL present in the IP header. Its value decreases by 1 at each hop. So the TTL  ensures that the packet does not stuck in the network by discarding the packet once its value becomes zero.

MPLS NETWORK – Label Switched Path (LSP)

The MPLS Network consists of LSR i.e. Label Switch Routers. These are named so as they are capable of understanding the MPLS labels. There are 3 types of LSR –

• Ingress LSR: The Ingress LSR receive unlabeled IP packet and PUSH the label on it. Ingress LSR are present at the beginning of the network.
• Egress LSR:  Egress LSR POP the label from the incoming packet and forward it as an IP packet. Egress LSR are present at the end of the network.
• Intermediate LSR: Intermediate LSR are present in between Ingress and Egress routers, that is why they are called intermediate routers. These routers receive the labeled packet, SWAP the label of the packet and forward it to the next hop. Thus carrying out MPLS forwarding of the packet.

This type of path is also known as PUSH – SWAP- POP Label Switched Path. Thus a network packet follows a fixed path known as the Label Switched Path or LSP in MPLS forwarding

MPLS Forwarding & how is it different from IP Routing

So after understanding the basics of MPLS Network, we can sum up the process of MPLS forwarding easily.

In MPLS forwarding, the Ingress router present at the beginning of the MPLS network pushes a label on the incoming network packet. This label specifies a particular path that the network packet has to follow i.e the Label Switched Path. Each LSR contains Label Forwarding Information Base(LFIB)which base guides the LSR to swap the label with its corresponding outgoing label. This allows the packet to transmit through the network. The Egress router present at the end of the LSP, pops the label of the packet and it is then moved forward as normal IP packet.

In contrast to MPLS forwarding, in IP routing each network packet contains a source IP address and a destination IP address and is passed through several routers in between through hop-by-hop mechanism. Each router contains the routing table that provides information to the next hop till it finally reaches the destination.

So, MPLS forwarding is done on the basis of labels given to the packets while in IP forwarding it is done on the basis of the IP address.

The detailed comparison between the two can be studied through the below given comparison table. (Credit:ipwithease.com)

Comparison Table : MPLS vs IP Routing

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

Every network is a collection of nodes and links for their interconnection. The arrangement of these nodes and links in a specific manner is known as topology. It would define how devices within will connect and how data moves from one node to another node. It can also be simply referred to as a schematic description of arrangement of network elements. There are different types of network topologies but the selection would depend on a number of factors such as performance, throughput, fault tolerance, costs etc. Network topology is defined both at physical and logical level. Logical topology defines how data will flow between network devices whereas physical topology will define physical connections within the network. 

Today we look more in detail about Tree network topology, its advantages and disadvantages and use cases etc.  

What is a Tree Network Topology?

Choice of topology for your network is crucial as it affects its function and performance . So, choosing the right topology for your organization is quite an important decision. By choosing the right topology for your organization, you can reduce operational costs, improve performance and achieve resource allocation optimization. 

Tree network topology is a combination of the bus and the Star network. More than one-star networks can be connected together using a bus network. Different branches, that is the star network looks in tree topology which are connected on a bus at different points at a particular distance and the bus network looks like a root of a tree. 

The central ‘root’ node is connected to one or more other nodes which are one level lower in the branching with a point-to-point link between each second level node and the top level ‘root’ node. Each of the second level nodes is connected to the ‘root ‘ node but also has one or more nodes connected to one level below again (third level). The ‘root’ node is top most in the hierarchy and there is no node above it, all other nodes are descendants of the ‘root’ node. There is only one path between two nodes for transmission of data. Thus, it is a parent-child hierarchy.

The central hub contains a repeater, which looks at incoming bits and regenerates them as the full blow signal for 0 or 1 as required. This allows digital signals to travel long distances. The central hub is also known as an active hub. The tree topology may have many secondary hubs, which may be active or passive in nature.

Advantages of Tree Network Topology 

• For networks where neither star nor bus topology can be implemented tree topology is best alternative. 
• Support for broadband transmissions – It is mainly used to provide broadband transmission as signals can be sent to long distances without being weakened.
• Ease of expansion – new devices can be added to the existing network without much hassles. Whole readymade branches can be attached to the main cable channel which is bus network which is especially designed for expansion of network 
• Not just physical appearance but logically also branches of the tree network are divided functionally and each segment of branches can be managed separately. 
• Ease of management – the whole network is divided into segments known as Star networks which are easy to manage and maintain
• Error detection – error detection is quick and error correction is also easy as roles are divided, responsibilities and functions are segregated 
• Limited failures – the breakdown of one station in the hierarchy don’t impact availability of the entire network. Each of the branches are connected with base cable channel with a separate point to point wiring so damage to one branch will not affect function of another branch
• Point to point wiring – Individual segments are point to point connected 

Disadvantages of Tree Network Topology

• Difficult to identify fault and troubleshoot – Its fault occurs in the node; it becomes tough to troubleshoot the issue as defective node detection is tedious task
• Higher costs – devices required for deployment of broadband transmission are expensive
• Failures – even though one branch cannot cause impact to other , but its main dependency is on the bus cable and failure in main bus cable could lead to downfall of entire network
• Complexity in reconfiguration – addition of new device requires expertise in configuration 
• Maintenance costs are more with number of nodes or branches and wiring extensions

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Hybrid Network Topology

Bus Network Topology

Today we look more in detail about extended Star network topology , its need, advantages and disadvantages and use cases etc.  

About Extended Star Network Topology

An extended star network topology includes an additional networking device that is directly connected to the central networking device. It seems like a mesh of switches which are interconnected to the network and once central networking device which controls the network. Star topology is the most widely used network topology at homes and offices.

It has different nodes that are known as hosts and the central node of communication called a hub or the server. The central hub is also called peripheral host and nodes are called leaves of the peripheral host. The central hub is the central point of communication and if any node needs to transfer a message to another node the first step is to send a message to the central hub and then the central hub will transfer the message to the recipient node. 

This sort of network setup is known as star topology or extended star topology and it is good for short distance communication which can be used in offices, homes, computer labs, and small buildings where the LAN is established. All the nodes can be managed from a one-point central hub. The central hub has content addressable memory (cam) table which is used to store the address of all nodes so that all information of connect nodes can be managed by the central hub in the proper manner. 

In extended star topology instead of connecting all devices to the central unit, we have sub central devices added to allow more functionality for organization and subnetting.

Advantages of Extended Star Topology

• The performance is better in extended star topology compared to bus topology. As there is no unnecessary transmission of messages in the network. The message is transferred only between source node , a central hub and destination node 
• Ease of adding devices as network expansion happens
• One node failure do not bring down entire network
• The new equipment can be added to the network and connected to the central hub. The nodes can be easily removed from the network 
• It is easy to find device and cable issues
• It can be upgraded to faster speed
• This topology helps to control multiple nodes at the same time 
• The data transmission can be done across the network and there is very less chance of network failure as compared to its counterparts like bus topology 
• Mostly widely used so support is easily available

Disadvantages of Extended Star Topology

• As all nodes are connected to central hub it requires more wire at each node to connect to central hub which increases its setup cost hence it requires more cable than a bus or ring network
• As all nodes are connected to the central hub and if central hub goes down it will lead to whole network failure and bring down entire network 
• Increase in number of connected nodes will decrease the performance of central hub or switch and will cause network congestion 
• Comparatively higher costs than bus networks (Installation and equipment)

Uses of Extended Star Topology

• The extended star topology is majorly used where we need to connect multiple nodes to one central node and control of all nodes is from the central node.  
• It can be used to establish the LAN (Local Area network) connection. The LAN connection helps to connect systems to one central point. The LAN connections are meant for shorted distances
• It helps to transmit the data and information to any other node on the network. One node can send message to any other node provided all nodes are connected to central hub or switch
• It is used in homes and offices. The failure probability of the network can be reduced using extended star topology. As the nodes connected to one central hub there is a little chance that network will fail as the nodes are independent of each other and connected to central hub or switch

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Hub and Spoke/Star Network Topology

What is LAN? Detailed explanation

Today we look more in detail about Hybrid network topologies, its types , pros and cons and use cases etc.  

Hybrid Network Topology

Different applications use hybrid network topology as it is more efficient compared to fundamental mechanisms. It can be deployed in different environments. It provides users the benefit to create, run and manage applications. There are various sectors in which hybrid topology is widely used such as educational institutions, banking sector, automated industries, financial sector, research organizations and multinational companies. The hybrid topology is created by mixing two topologies such as full mesh topology, extended star, partial star, point to point network and so on. It is good for use on multi-floor buildings and departments in offices and also at homes. 

Types of Hybrid Network Topologies

There are several types of hybrid network topologies which integrate many basic topologies to create a new form of topology as per the requirements. These topologies are hieratical in nature and constitution. Hybrid topology has the capability to integrate both physical and logical topologies. We will learn more in detail about these topologies in this section.

Star-Ring Hybrid topology 

The Star and Ring topology is used to create this topology. Using ring topology, two or more-star topologies are linked with the help of a physical (wire) connection. The data flows in both ways unidirectional or bidirectional. Whereas in original ring topology the bidirectional method of data flow provides the functionality that there is no impact on whole network data flow when one node of the original ring topology fails and data reaches a connecting node in this type of star topology. 

Star-Bus Hybrid topology 

This is achieved by combination of bus and star topology. The bus topology allows two or more-star topologies to be linked via a wire connection. The original bus topology interrelates the distinct star topologies and provides a backbone structure.

Hierarchical Hybrid Network topology 

This topology is also called network tree topology. It is a minimum level like two to a maximum level, and maximum is known as root or parent node. The next level in hieratical structure includes a child node which is level three. Except the top-level nodes each node provides a maximum parent node and the nodes at minimum level, peripheral nodes function like parent nodes and referred as leaf nodes. 

Pros and Cons of Hybrid topology

PROS

• Reliability is higher in hybrid topology due to better fault tolerance. If a node gets damaged between network, it is possible to single out the damaged node from rest of the network without impacting the processing of network
• Effective as mixing of two topologies brings benefits of both such as high tolerance is provided by star topology and good data reliability is provided by ring topology
• Scalability is another benefit of hybrid topologies. As it involves easy integration of additional concentration points or new hardware components. Without disturbing the existing architecture, it is easy to extend network size.
• Flexibility is great virtue of this topology as it can be implemented for different network environments 
• They offers benefits like data communication, signal strength, throughput and high-end equipment integration 
• It has ability to transfer data easily between different types of networks

CONS

• Complexity is one of the drawbacks of this topology. It is challenging as different topologies are linked in hybrid structure. It is tough for designers to create such structure and requires efficient installation and configuration process 
• Purchase and management of hybrid topology is comparatively expensive then basic topologies. The hubs are also required in this technology to connect two different networks which are quite expensive. The hybrid topology may require advanced network devices , loads of cables and much more as architecture is usually quite larger in scale. 
• For quick fault identification it requires a multi-access unit to bypass faulty devices so that there is no or limited impact on network availability. 

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Ring Network Topology

Hub and Spoke/Star Network Topology

Today we look more in detail about Partial mesh network topology , its need, advantages and disadvantages and use cases etc.  

About Partial Mesh Network Topology

Partial mesh is a structure to map routers in such a way that they are coupled tightly among themselves but still not fully interconnected. Partial mesh is a subset of full mesh and links are arranged in a strategic manner based on frequent operating paths or signals to facilitate usage. Users of partial mesh enjoy better usability and time management but there are definitely some additional benefits using partial mesh in your organization. Only a few nodes, not all are attached with other nodes.  

There is no centralized regulation in partial mesh, for any number of connections in the network no admin or controller exists. They are applicable to Wireless area networks as they are meant to cover large geographical areas. WANs as we are aware are suitable to handle large crowds and numerous devices or remote areas. It is not simply more redundant than Hub and spoke WAN topology but it lies somewhere between Mesh and Spoke in terms of costs and it is comparatively less expensive than full mesh but costlier than spoke.

Partial mesh networks are highly robust and if a user loses connection still data will not be lost as data is not hosted centrally in one location. Partial mesh topology creates datasets with better management capabilities and integrity. There is validation and tracking for any misconduct that occurs.

Principles of Mesh Network Topology

Mesh topology works on two principles as under.

• Routing – in routing mode data is communicated in a pre-arranged path containing many hopping across nodes. All intermediary nodes require to be active and connected then only data will be transmitted over the network
• Flooding – the data is transmitted to every active node. The node looks at address data and passes it to next active node if data is not supposed to be addressed

Protocols used in Partial Mesh Topology

Protocols fit in layer 3 of the OSI model and define standards for data communication between two nodes. The three kinds of protocols: Proactive, Hybrid and Reactive are used in this topology. Each protocol plays a vital role in management of the networking and impacts performance and scalability. 

1. Proactive protocol – provides constant self-monitoring of nodes with the help of feedback mechanisms from nodes. If any node fails, it reroutes the network path. Maximum up time is ensured and quick recovery from failure with robust performance. In a dynamic environment chances of collision are increased but in a static environment it is ideal where network paths don’t change very often. 
2. Hybrid protocol – offers the best combination as per environment and communication requirements and uses reactive methods and characteristics of proactive protocol . network cost optimization can be achieved using this
3. Reactive protocol – is used to determine the network path at the time of request for transmission of data. It defines the optimal path and scans the entire network and best fit for a dynamic environment. 

Advantages of Partial Mesh Topology 

• High volume of data transmission can be handled at a very fast rate to any number of devices. Data transmission is possible from different devices simultaneously 
• No effect of failure even if one hub or end of the terminal is deactivated. Things are arranged in such a manner that best optimal path is automatically directed without overloading the process
• The expansion and modification is possible in every sense and without impacting existing nodes or terminals. As each node acts like a router. There are no exclusive routers. 
• It is an optimal solution for best user experience with minimum charges 
• It is a very robust structure ; a connection only communicate with others only if they are allowed to do so and this eliminate chances of misconduct
• It is very easy to diagnose and identify fault 
• Customization could offer better security and privacy to users as desired
• As failures do not disrupt processes , data transmission has consistency 

Disadvantages of Partial Mesh Topology 

• Since each node acts as router the complexity is increased
• Overall cost of this network is too high as compared to other topology options
• Setup and maintenance is tough and even administration
• All the time in this topology each node will have to remain active which led to high power consumption and load increase

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Hybrid Network Topology

Hub and Spoke/Star Network Topology

Ring topology is a type of network topology in which each network device is connected to two other devices, forward and backward forming a single continuous path for signal transmission. It forms a ring, as each network device is connected to the other with the last one connected to the first forming a ring network. In a ring network, data travels from one device to the next in the form of packets.  Each device in a ring topology has a repeater, if the received data is intended for other device then repeater forwards this data until the intended device receives it.

Types of Ring Topology:

On the Basis of the data flow, ring topology can be of two types-

1. Unidirectional Ring Topology
2. Bidirectional Ring Topology

• Unidirectional Ring Topology : It involves data traffic in one direction, either clockwise or anticlockwise. This data network is also called a half-duplex network. E.g.- SONET network, SDH network etc.
• Bidirectional Ring Topology : It involves data traffic in both the directions and is thus called a full-duplex network. Bidirectional data transmission is possible by having two connections between each network node, thus making two ring networks with data flow in opposite direction to each other. This type of topology with two rings is sometimes also referred to as the Dual Network Topology.

Advantages of Ring Network Topology:

• Easy to install.
• As the data flows in one direction, it reduces the chance of packet collisions.
• Performs better than bus topology under heavy traffic.
• No need of network server to control network connectivity between workstations.
• Additional devices can be added without impacting the performance.

Disadvantages of Ring Network Topology:

• The network requires to be shut down for addition or removal of nodes .
• A data packet must pass through all the nodes in unidirectional flow.
• Failure of one device disrupts the entire network.

Related – Star Network Topology

TYPES OF TRANSMISSION MODES

The different types of transmission mode are:

Simplex, Half duplex and Full duplex

• Simplex : As the name signifies, it is the most simple mode of transmission. It only sends information/data in one direction i.e. from the sender to the receiver. The receiver cannot reply to the sender. For example, a radio broadcast is a simplex channel. As it sends signals to the audience but never receives signals back from them.

• Half duplex : In a Half Duplex Mode, the data/information can be sent in both the directions, but one at a time and not simultaneously. For example, a walkie-talkie is a device that can be used to send message in both  the directions, but both the persons can not exchange the message simultaneously. One can only speak and the other can only listen.

• Full Duplex : In a Full Duplex Mode, the transmission of the information between the sender and the receiver can occur simultaneously. It is used when communication in both direction is required all the time. For example, a telephone is a two way communication in which both the persons can talk and listen to each other at the same time.

COMPARISON OF TRANSMISSION MODES

The differences between the three modes of transmission can be summarized as below:

One great advantage of GRE is that it allows routing of IP packets between private IPv4 networks which are separated over public IPv4 internet. GRE also supports encapsulating IPv4 broadcast and multicast traffic. GRE tunnels are not secure because Generic routing encapsulation does not encrypt its Data payload. In mealtime, GRE used together with other secure tunneling protocols like IPsec provides network security.

Following are key fields of the GRE Header.

Flag C (Checksum Present): Used to indicate that the Checksum field is present and contains valid information, when set to 1.

Flag R (Routing Present): Used to indicate that the Routing fields are present and contain valid information, when set to 1.

Flag K (Key Present): Used to indicate that the Key field is present in the GRE header, when set to 1.

Flag S (Sequence Number Present): Used to indicate that the Sequence Number field is present, when set to 1.

Flag s (Strict Source Route): Set to 1 the routing information consists of Strict Source Routes.

Recursion Control and Version Number are normally set to 0

Protocol Type: Protocol Type field is used to mention the protocol payload of the GRE packet. For IP, this field is set to 0x800

Checksum: Checksum field value is used to check the integrity of the GRE header and the payload.

Key: Key field value is used to authenticate the GRE packets encapsulate.

Sequence Number: Sequence Number filed value is used to track the sequence of GRE packets.

Below is a diagram shows Wireshark capture image of a GRE Encapsulation and GRE Header fields.

Generic routing encapsulation provides a private, secure path for transporting packets through an otherwise public network by encapsulating or tunneling the packets. GRE encapsulates data packets and redirects them to a device that de-encapsulates them and routes them to their final destination. It allows source and destination switches to operate as if they have a virtual point-to-point connection with each other because the outer header applied by GRE is transparent to the encapsulated payload packet.

The subnet mask or the address mask separate network address with the host address in the IP.

<Network><Host>

Furthermore, if there is an additional subnet needed, it is done using the subnet calculation and we can retrieve subnet information directly from the IP address.

IP address

IP stands for Internet Protocol Address. It is a unique address given to each and every device which uses the internet. There are 2 main functions over – Host and the Network. IP Address has many utilities like we can get the location of the device using the IP address.

There are different versions of the IP address –

• The older one that was used is IPV4. IPV4 is an address with 32bit number.
• The new version that was developed later on was called IPV6 and it consists of 128 bits.

The name – Subnet Mask

If you are wondering how the name came into the existence and why it is called subnet mask – It is because the IP address’s network address is identified using this. Here, the bitwise AND operation is carried out directly on the netmask and using this the IP is obtained. Therefore, it is called the subnet mask and some people also call it by the name address mask.

More about Subnet

A subnet mask is typically 32 bit. It masks IP addresses and also divides the IP addresses into the host address and the network address. In other words, the network address is separated with the help of Subnet mask. It is done by setting all the networks bit to the new state. Then the networks bits are reset to 1 and the host bits are set to the 0.

The host addresses are reserved here and it can’t be given to any of the hosts. The two address that is already reserved for special purposes are the 0 address that is assisted for the network address and the other one is the 255 that is assigned to the broadcast address.

As this both of the host address is already assigned for the special purpose, one can’t assign them to end hosts.

IP , Subnet and IANA –

IP address is displayed in the human-readable form. Anyone can know the IP and even remember it. However, the IP address can be static or it can be dynamic. Therefore, it is not the same all the time.Coming to the examples of the IP address, in IPV4, the IP address is written as 172.16.254.1 whereas, in the IPV6, the address is written as 2001:db8:0:1234:0:567:8:1. IP address along with Subnet mask can be depicted in following format – 192.168.1.15/24 . This can be equivalent to the subnet mask used, that is 255.2555.255.0.

If you are looking to go more deeply into the IP address and who assigns the IP address then it is an IANA and 5 RIRs who manages the IP addresses throughout the globe and not only for any particular country.

IANA stands for the Intenet Assigned Numbers Authority whereas RIRs stands for Regional Internet Registries. The RIR is only responsively to manage the numbers in their area and not for the whole globe. However, the 5 different RIRs are surely covering the entire globe along with the IANA. They provide the IP to the end users as well as the ISPs. The IP address we get is given by the ISP that is the Internet Service Provider.

Torrenting is a P2P (peer-to-peer) file sharing technology used to share files efficiently. This technology relies on a community of decentralized users for file sharing  rather than being dependent on traditional single website or source for downloading. A user can download the file from the direct source as well as from other users of the same torrent. This makes the transfer smoother by significantly reducing the network load.

Before discussing Torrenting technology in detail, let’s understand – What is torrent? The word “torrent” simply means a computer file containing metadata to hold information.

Terminology to understand the working of Torrents –

Peers: All the users involved in the sharing of files through torrent P2P sharing are called peers.

Seeders: Seeder is a user who is downloading a file from a torrent and simultaneously uploading it to be used by others.

Swarms: A number of peers sharing (downloading or uploading) the same torrent files are called swarms.

Indexers: The websites which work as a search engine for the files and content to be downloaded through a torrent are known as indexers. E.g. – Extratorrent , Torrentz, RarBG  or Piratebay are some of the widely used indexers.

Trackers: Trackers are servers that act as bridges between different torrent users. Thus aiding the smooth and fast transfer of data by routing small pieces of files between each torrent downloader and uploader.

Leechers:  Leechers are the users that are only downloading and have disabled uploading. Its not considered an ethical practice as their intention is not to help the other peers for download. Many trackers ban leechers.

BitTorrent Client: One of the main requirements for torrenting is the presence of a client. Programs that enable file transfer using BitTorrent protocol are called BitTorrent clients

Ratio – The relationship between your uploading (seeding) and downloading (leeching) score. The ratio for each file should be greater than 1.0, means you upload at least the same amount as you download.

Magnet link – Instead of downloading a torrent file, magnet links identify files and sources and allow your torrent client to start downloading immediately.

How torrenting works? (BitTorrent Client)

When we open a Web page and click on a link to download a file we want, BitTorrent client software communicates with a tracker to find other computers running BitTorrent that have the complete file (seed computers) or those with a portion of the file (peers that are usually in the process of downloading the file).

The tracker then identifies the swarm.

The tracker helps the client software to transfer pieces of the file we want with other computers in the swarm. Thus our computer receives multiple pieces of the file simultaneously.

Continuous use of the BitTorrent client software after our download is complete, helps others to receive “.torrent files” from your computer. This results in an improved future download rates as we are ranked higher in the “tit-for-tat” system.

By downloading multiple pieces at the same time, the overall speed is greatly improved. The more is the number of computers in the swarm, the faster is the file transfer, that’s the reason that BitTorrent is useful especially for large, popular files. To keep yourself safe during torrenting, always use a VPN, use Anti-Virus Software, don’t download illegal content and try to use private trackers.

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What is a Kill switch in VPN?

Is It Legal To Use A VPN?

In case you are preparing for your next job interview, then check our e-book on VPN Interview Questions and Answers in easy to understand PDF Format, explained with relevant Diagrams (where required) for better ease of understanding.

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VRFs are the same methods of network isolation/virtualization as VLANs. VLANs are used at the L2 and VRFs are L3 tools. VRFs are to routing table like VLANs are to LANs.

Related – VDC vs VRF