VIRTUAL NETWORK
Virtual networks can be thought of as separate networks within a larger network. Administrators can create a separate network segment consisting of a range of subnets (or a single subnet) and control traffic that flows through the cloud network. The main purpose of a virtual network is to enable a data centre or service provider network to provision the most suitable and efficient networking structure for the applications it hosts – and to alter that structure as conditions warrant, using software rather than requiring physical changes in connections to hardware. The ability to virtualize workloads (applications) and to transport them across network infrastructure with minimal service degradation gave rise to the first cloud architectures. With a cloud solution, these virtual networks are known as VNets or Virtual Private Clouds (VPC). These act as a representation of a network in the cloud, giving you a cloud network.
PROTOCOLS
In networking, a protocol is a set of rules for formatting and processing data. Network protocols are like a common language for computers. The computers within a network may use vastly different software and hardware; however, the use of protocols enables them to communicate with each other regardless.
On the Internet, there are different protocols for different types of processes. Protocols are often discussed in terms of which OSI model layer they belong to. The OSI (Open Systems Interconnection) Data Model is an ISO standard for computer networks design and functioning that involves at least 7 layers, each playing a specific role when applications are communicating over the net. During the sending process, each layer (from top to down) will add a specific header to the raw data. At the reception, headers are eliminated conversely until the data arrived to the receiving application.
SUBNETS
A subnet or subnetwork is a smaller network inside a large network. Subnetting makes network routing much more efficient. Through subnetting, network traffic can travel a shorter distance without passing through unnecessary routers to reach its destination. Subnets offer a way of organizing your network to help to reduce network congestion. When you have a lot of traffic flowing between particular parts of your network, it can help to group those parts in a single section, so the traffic doesn’t have to travel across the entire network to get from place to place. Separating out small parts of your network into subnets allows traffic to flow more quickly and to avoid taking unnecessary routes, adding traffic where it isn’t needed.
In addition, subnetting helps in efficiently allocating IP addresses and prevents large numbers of IP addresses from going unused. Subnets are usually set up geographically for particular offices, or for particular teams within a business to allow their network traffic to stay within the location.
ROUTERS AND ROUTING TABLES
Routers examine the destination IP address of a received packet and make routing decisions accordingly. To determine which interface the packet will be sent, routers use routing tables. A routing table lists all networks for which routes are known. Each router’s routing table is unique and stored in the RAM of the device. When a router receives a packet that needs to be forwarded to a host on another network, it examines its destination IP address and looks for the routing information stored in the routing table. Each entry in the routing table consists of the network and the subnet mask, the remote router and the outgoing interface.
NETWORK SWITCHES
Switches connect network segments, providing full-duplex communication, valuable network performance data and efficient use of network bandwidth. It is a device that operates at the Data Link layer of the OSI model—Layer 2. It takes in packets being sent by devices that are connected to its physical ports and sends them out again, but only through the ports that lead to the devices the packets are intended to reach. They can also operate at the network layer–Layer 3 where routing occurs.
When a device sends a packet to another device, it enters the switch and the switch reads its header to determine what to do with it. It matches the destination address or addresses and sends the packet out through the appropriate ports that leads to the destination devices.
PORTS
A port is a virtual point where network connections start and end. Ports are software-based and managed by a computer’s operating system. Each port is associated with a specific process or service. Ports allow computers to easily differentiate between different kinds of traffic: emails go to a different port than webpages, for instance, even though both reach a computer over the same Internet connection.
Ports are standardized across all network-connected devices, with each port assigned a number. Most ports are reserved for certain protocols — for example, all Hypertext Transfer Protocol (HTTP) messages go to port 80. While IP addresses enable messages to go to and from specific devices, port numbers allow targeting of specific services or applications within those devices.
NETWORK TOPOLOGIES
Network topology is the way a network is arranged, including the physical or logical description of how links and nodes are set up to relate to each other. There are two approaches to network topology: physical and logical. Physical network topology refers to the physical connections and interconnections between nodes and the network—the wires, cables, and so forth. Logical network topology refers to the conceptual understanding of how and why the network is arranged the way it is, and how data moves through it.
There are many different ways network nodes can be connected together. Most common topology types are Bus, Ring, Mesh, Star and Hybrid.
CLIENTS AND SERVERS
An important relationship on networks is that of the server and the client. A server is a computer that holds content and services such as a website, a media file, or a chat application. A good example of a server is the computer that holds the website for Google’s search page: http://www.google.com. The server holds that page, and sends it out when requested.
A client is a different computer, such as your laptop or cell phone, that requests to view, download, or use the content. The client can connect over a network to exchange information. For instance, when you request Google’s search page with your web browser, your computer is the client.
FIREWALL
A firewall is a network security device that monitors incoming and outgoing network traffic and permits or blocks data packets based on a set of security rules. Its purpose is to establish a barrier between your internal network and incoming traffic from external sources (such as the internet) in order to block malicious traffic like viruses and hackers. Firewalls guard traffic at a computer’s entry point, called ports, which is where information is exchanged with external devices.
Firewalls can either be software or hardware, though it’s best to have both. A software firewall is a program installed on each computer and regulates traffic through port numbers and applications, while a physical firewall is a piece of equipment installed between your network and gateway.
