WIRELESS NETWORK

NETWORK THE WORLD

Wireless Network refers to any type of computer network that is wireless, and is commonly associated with a telecommunications network whose interconnections between nodes is implemented without the use of wires, such as a computer network (a type of communications network).
Wireless telecommunications networks are generally implemented with some type of remote information transmission system that uses electromagnetic waves, such as radio waves, for the carrier and this implementation usually takes place at the physical level or "layer" of the network.

Wireless Local Area Network (WLAN) is similar to other wireless devices and uses radio instead of wires to transmit data back and forth between computers on the same network.
# Wi-Fi: Wi-Fi is a commonly used wireless network in computer systems which enable connection to the internet or other machines that have Wi-Fi functionalities. Wi-Fi networks broadcast radio waves that can be picked up by Wi-Fi receivers that are attached to different computers or mobile phones.
# Fixed Wireless Data: Fixed wireless data is a type of wireless data network that can be used to connect two or more buildings together in order to extend or share the network bandwidth without physically wiring the buildings together

Wireless MAN

Wireless Metropolitan area networks are type of wireless network that connects several Wireless LANs.

* WiMAX is the term used to refer to wireless MANs and is covered in IEEE 802.16d/802.16e.
Mobile devices networks

    * Global System for Mobile Communications (GSM): The GSM network is divided into three major systems which are :the switching system, the base station system, and the operation and support system (Global System for Mobile Communication (GSM)). The cell phone connects to the base system station which then connects to the operation and support station; it then connects to the switching station where the call is transferred where it needs to go (Global System for Mobile Communication (GSM)). This is used for cellular phones, is the most common standard and is used for a majority of cellular providers.
    * Personal Communications Service (PCS): PCS is a radio band that can be used by mobile phones in North America. Sprint happened to be the first service to set up a PCS.
    * D-AMPS: D-AMPS, which stands for Digital Advanced Mobile Phone Service, is an upgraded version of AMPS but it is being phased out due to advancement in technology. The newer GSM networks are replacing the older system.

ROUTING

Routing (or routeing) is the process of selecting paths in a network along which to send data or physical traffic. Routing is performed for many kinds of networks, including the telephone network, the Internet, and transport networks. Routing directs forwarding, the passing of logically addressed packets from their source toward their ultimate destination through intermediary nodes; typically hardware devices called routers, bridges, gateways, firewalls, or switches. Ordinary computers with multiple network cards can also forward packets and perform routing, though they are not specialized hardware and may suffer from limited performance. The routing process usually directs forwarding on the basis of routing tables which maintain a record of the routes to various network destinations. Thus constructing routing tables, which are held in the routers' memory, becomes very important for efficient routing. Routing, in a more narrow sense of the term, is often contrasted with bridging in its assumption that network addresses are structured and that similar addresses imply proximity within the network. Because structured addresses allow a single routing table entry to represent the route to a group of devices, structured addressing (routing, in the narrow sense) outperforms unstructured addressing (bridging) in large networks, and has become the dominant form of addressing on the Internet, though bridging is still widely used, albeit within localized environment

ROUTER

A router (pronounced /'rautər/ in the USA and Australia, and pronounced /'ru:tər/ in the UK) is a computer whose software and hardware are usually tailored to the tasks of routing and forwarding information. Routers generally contain a specialized operating system (e.g. Cisco's IOS or Juniper Networks JUNOS and JUNOSe or Extreme Networks XOS), RAM, NVRAM, flash memory, and one or more processors. High-end routers contain many processors and specialized Application-specific integrated circuits (ASIC) and do a great deal of parallel processing. Chassis based systems like the Nortel MERS-8600 or ERS-8600 routing switch, (pictured right) have multiple ASICs on every module and allow for a wide variety of LAN, MAN, METRO, and WAN port technologies or other connections that are customizable. Much simpler routers are used where cost is important and the demand is low, for example in providing a home internet service. With appropriate software (such as SmoothWall, XORP or Quagga), a standard PC can act as a router.

Routers connect two or more logical subnets, which do not necessarily map one-to-one to the physical interfaces of the router. The term layer 3 switch often is used interchangeably with router, but switch is really a general term without a rigorous technical definition. In marketing usage, it is generally optimized for Ethernet LAN interfaces and may not have other physical interface types.

Routers operate in two different planes:

* Control Plane, in which the router learns the outgoing interface that is most appropriate for forwarding specific packets to specific destinations,
* Forwarding Plane, which is responsible for the actual process of sending a packet received on a logical interface to an outbound logical interface.

SWITCH

A network switch is a computer networking device that connects network segments.

In the past, it was faster to use Layer 2 techniques to switch, when only MAC addresses could be looked up in content addressable memory (CAM). With the advent of ternary CAM (TCAM), it was equally fast to look up an IP address or a MAC address. TCAM is expensive, but very appropriate for enterprise switches that use default routes plus a moderate number of other routes. For routers that need a full Internet routing table, TCAM may not be cost-effective.

The first Ethernet switch was introduced by Kalpana in 1989.

FUNCTION OF SWITCH

As with hubs, Ethernet implementations of network switches support either 10/100 Mbit/s or 10/100/1000 Mbit/s ports Ethernet standards. Large switches may have 10 Gbit/s ports. Switches differ from hubs in that they can have ports of different speed.

The network switch, packet switch (or just switch) plays an integral part in most Ethernet local area networks or LANs. Mid-to-large sized LANs contain a number of linked managed switches. Small office, home office (SOHO) applications typically use a single switch, or an all-purpose converged device such as gateway access to small office/home office broadband services such as DSL router or cable, WiFi router. In most of these cases, the end user device contains a router and components that interface to the particular physical broadband technology, as in the Linksys 8-port and 48-port devices. User devices may also include a telephone interface to VoIP.

Layer-1 hubs versus higher-layer switches

A network hub, or repeater, is a fairly unsophisticated broadcast device, and rapidly becoming obsolete. Hubs do not manage any of the traffic that comes through them. Any packet entering a port is broadcast out or "repeated" on every other port, save the port of entry. Since every packet is repeated on every other port, packet collisions result, which slows down the network.

Hubs have actually become hard to find, due to the widespread use of switches. There are specialized applications where a hub can be useful, such as copying traffic to multiple network sensors. High end switches have a feature which does the same thing called port mirroring. There is no longer any significant price difference between a hub and a low-end switch.

ROUTING PROTOCOLS

· These protocols that filter network traffic.
· They have many routes between them.
· It depends on the router to choose the best path i.e maintain routing table.
· It can do different number of functions like hop number, bandwidth, latency, average error rates, current network traffic etc.

There are different types of protocols of routing.
· Routing information protocols (RIP)
· Interior gateway routing protocol (IGRP)
· Open shortest path first (OSPF)
· Exterior gateway protocol (EGP)
· Enhanced interior gateway routing protocol (EIGRP)
· Border gateway protocol (BGP)
· Intermediate system-to-intermediate system (IS-IS)

Routing fundamentals

The network layer has two types of protocols like routing protocols and routed protocols.
· In routing protocols router share information with each other. Protocols like RIP, IGRP, EIGRP, and OSPF.
· In routed protocols any of the network protocols address a host and a destination on to the given network. Protocols like IP, IPX, and NetBEUI.
· Another thing is that basically there are two types of routing.
· Dynamic routing.
· Static routing.
· Default routing.

Dynamic routing

· In dynamic routing monitor network can change their routing tables.
· They knows everything about the internet work.
· They can do security concerns for the path selections.
· Different factors can be involved in dynamic routing. They are as follows.
· Bandwidth
· Delay
· Load
· Reliability
· Hop count
· Ticks
· Cost

Dynamic update

· The knowledge is contained in the updates.
· When the router send the updates.
· It tells us the location of the recipients updates.
· It is send by two different methods
· Broadcast method
· Event - driven.

Default routing

· In this technique they are defined by system administrator and define the path that is taken if there is no route known for destination.

Static routing

· In this type of routing system administrator can sets manual routes for the network.
· This type of configuration can reduce overheads of dynamic routing.
· It allows the internet work administrator to specify the information about the network.

Routing protocols technique

· Basically there are three types of routing protocols technique.
· Distance- vector examples are (RIP, IGRP)
· Link -state examples are (OSPF, BGP, EGP)
· Hybrid examples are (IS-IS, EIGRP)

Distance -vector:-

· In this technique it use distance -vector algorithm which uses a direction to any link in the interconnection network to determine the best route.
· Each router periodically send information to he neighbour on the cost to get to distance node.
· The main problem with distance -vector is that it updates the network step by step so it requires more bandwidth to process the information.

Problems with distance -vector

· Different types of problems are.
· Routing loops
· Counting to infinity
· Solutions
· setting infinity values
· split horizon
· hold-down timers
· same neighbour problem
· different neighbour better metric
· different neighbour poorer metric

Link state:-

· It maintains a complex database on the topology of the network.
· It uses the link state algorithm (LSA) to advertise the routing information from routers.
· Each router builts up a topological database with themselves at the top of the tree.
· Routers keep communicating with neighbours at latest state.

Problem with link-state

· It requires more processing power to communicate with each other.
· It requires more memory to store LSA and topological database.
· Link state updates
· Scaling
· It initially sends up high demand for updates.

Hybrid routing

· It uses a combination of both balance and hybrid routing.
· It uses distance -vector technique for more accurate metrics to determine the best path.
· It reports routing information when change occurs in topology - link-state.
· Intermediate system-to-intermediate system (IS-IS).
· Enhance interior gateway routing protocol (EIGRP).

Have a Nice Time!!!!!!!!