Network Management DevicesBRIDGE, SWITCHES, GATEWAYS, REPEATERS, HUBS, ROUTERS

Rahul PRoll no:35SSM Polytechnic college, Tirur

Topics Covered Network Management DevicesRouters Bridges Repeaters Hubs Switch Gateway

Network Management Devices

With the expansion of the world wide web and the Internet, computer networks have become very large and complex, making them impossible to manage manually. In response, a suite of network management software was developed to help reduce the burden of managing the growing complexity of computer networks

Routers

A router is a networking device that forwards data packets between computer networks. Routers perform the traffic directing functions on the Internet. A data packet is typically forwarded from one router to another router through the networks that constitute the internetwork until it reaches its destination node

A router is connected to two or more data lines from different networks. When a data packet comes in on one of the lines, the router reads the address information in the packet to determine the ultimate destination. Then, using information in its routing table or routing policy, it directs the packet to the next network on its journey

Routers (cont…)

A router may have interfaces for different physical types of network connections, such as copper cables, fiber optic, or wireless transmission. Its firmware can also support different networking communications protocol standards. Each network interface is used by this specialized computer software to enable data packets to be forwarded from one protocol transmission system to another

How does a router work?

A router may create or maintain a table of the available routes and their conditions and use this information along with distance and cost algorithms to determine the best route for a given packet. Typically, a packet may travel through a number of network points with routers before arriving at its destination. Routing is a function associated with the network layer (Layer 3) in the standard model of network programming, the Open Systems Interconnection (OSI) model

Routing in internet

Router /wired router

Wireless Router

Types of Routers• Broadband Routers

Broadband routers can do different types of things. Broadband routers can be used to connect computers or to connect to the Internet. If you connect to the internet through phone and using Voice over IP technology (VOIP) then you need broadband router. These are often a special type of modem (ADSL) that will have both Ethernet and phone jacks.• Wireless Routers

Wireless routers create a wireless signal in your home or office. So, any PC within range of Wireless routers can connect it and use your Internet. In order to secure your Wireless routers, you simply need to come secure it with password or get your IP address. Then, you'll log on into your router with the user ID and passwords will that come with your router.

Other Type of Router • Edge Router

This type of router are placed at the edge of the ISP network, the are normally configured to externalprotocol like BGP (Border gateway protocol) to another BGP of other ISP or large organization.• Subscriber Edge Router

This type of router belongs to an end user (enterprise) organization. It’s configured to  broadcast external BGP to it’s provider’s AS(s)• Inter-provider Border Router

This type of router is  for Interconnecting ISPs, this is a BGP speaking router that maintains BGP sessions with other BGP speaking routers in other providers' ASes.• Core Router

A router that resides within the middle or backbone of the LAN network rather than at its periphery. In some instances , a core router provides a step down backbone , interconnecting the distribution routers from multiple building of a campus ( LAN), or Large enterprise Location (WAN).

Bridges

• A network bridge is a computer networking device that creates a single aggregate network from multiple communication networks or network segments. This function is called network bridging.

 Bridging is distinct from routing, which allows multiple different networks to communicate independently while remaining separate. In the OSI model, bridging is performed in the first two layers, below the network layer

Types of Bridges• Transperent Bridge :

Transperent Bridges is invisible to the other devices on the network. Transperent Bridge only perform the function of blocking or forwarding data based on MAC address. MAC address may also be referred as hardware address or physical address. These addresses are used to built tables and make decision regarding whether a frame should be forward and where it should be forwarded.• Translational Bridge :

Translational Bridges are useful to connect segments running at different speeds or using different protocols such as token Ring and Ethernet networks. Depending on the direction of travel, a Translational Bridge can add or remove information and fields from frame as needed.

Types of Bridges

• Source-route Bridge :Source-route Bridges were designed by IBM for use on

Token ring networks. the SR Bridge derives the entire route of the frame embedded within the frame. This allows the Bridge to make specific decision about how the frame should be forwarded through the network.• Local Bridge :

A Local Bridge provides packet filtering and repeating services for the network segments of the same type. this is also called MAC-layer Bridge. This is the simplest type of Bridge because it has no need for packet filtering or buffering. This Bridge simply propagates the incoming packets to the appropriate ports or discard them.

Types of Bridges

Remote Bridge :• Remote Bridge connects network segments at different

locations, using WAN link such as MODEM or Leased line. The difference in speed between Local and wide area links, a remote Bridge uses internal buffer to store the data received from LAN while it is waiting for transmission to the remote site.

Repeater 

• A network device used to regenerate or replicate a signal. Repeaters are used in transmission systems to regenerate analog or digital signals distorted by transmission loss. Analog repeaters frequently can only amplify the signal while digital repeaters can reconstruct a signal to near its original quality.• In a data network, a repeater can relay messages

between sub networks that use different protocols or cable types. Hubs can operate as repeaters by relaying messages to all connected computers. A repeater cannot do the intelligent routing performed by bridges and routers.

Types Repeater 

• Telephone repeaterThis is used to increase the range of telephone signals in

a telephone line. They are most frequently used in trunk lines that carry long distance calls. In an analog telephone line consisting of a pair of wires Telephone repeaters were the first type of repeater and were some of the first applications of amplification.• Radio repeater

This is used to extend the range of coverage of a radio signal. A radio repeater usually consists of a radio receiver connected to a radio transmitter. The received signal is amplified and retransmitted

Types Repeater

• Optical communications repeaterThis is used to increase the range of signals in a fiber optic

cable. Digital information travels through a fiber optic cable in the form of short pulses of light. The light is made up of particles called photons, which can be absorbed or scattered in the fiber. An optical communications repeater usually consists of a phototransistor which converts the light pulses to an electrical signal, an amplifier to increase the power of the signal, an electronic filter which reshapes the pulses, and a laser which converts the electrical signal to light again and sends it out the other fiber

Hubs• A hub is a common connection point for devices in

a network. Hubs are commonly used to connect segments of a LAN. A hub contains multiple ports. When a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.

What Hubs Do

Hubs and switches serve as a central connection for all of your network equipment and handles a data type known as frames. Frames carry your data. When a frame is received, it is amplified and then transmitted on to the port of the destination PC. 

In a hub, a frame is passed along or "broadcast" to every one of its ports. It doesn't matter that the frame is only destined for one port. The hub has no way of distinguishing which port a frame should be sent to. Passing it along to every port ensures that it will reach its intended destination. This places a lot of traffic on the network and can lead to poor network response times.

Types Hubs

• Active, passive and intelligent hubs are the three of the most commonly know hubs.

• In a situation of data received being weak but readable, the active hub restores the signal before rebroadcasting the same.

• A passive hub on the other hand, do very little to enhance the performance of the network. Neither, it helps in any way in the troubleshooting operations which have become an integral part of the networking operations in recent times.

• Intelligent hub is another form of hub that is increasingly being used. An advanced version that comprises the best of both active and passive hubs

USB Hub

Ethernet Hub

Switch• In a telecommunications network, a switch is a device

that channels incoming data from any of multiple input ports to the specific output port that will take the data toward its intended destination. On an Ethernet local area network (LAN), a switch determines from the physical device (Media Access Control or MAC) address in each incoming message frame which output port to forward it to and out of. In a wide area packet-switched network such as the Internet, a switch determines from the IP address in each packet which output port to use for the next part of its trip to the intended destination.• Switches are a fundamental and essential part of any

computer network. Network switches make it possible for multiple devices like computers to connect and communicate together using Ethernet connections on a Local Area Network (LAN).

Types Switches Type of Network Switch

ConfigurationFeatures

Fully Managed Advanced options, can be configured, software needs updating, most costly option

Partially Managed Limited control, basic management, cheaper than fully managed

Unmanaged Plug and Play, no control options, easy to use, affordable

Gateway• In computer networking and telecommunications,

a gateway is a component that is part of two networks, which use different protocols. The gateway will translate one protocol into the other. A router is a special case of a gateway.• Gateways, also called protocol converters, can operate

at any network layer. The activities of a gateway are more complex than that of the router or switch as it communicates using more than one protocol.• Both the computers of internet users and the computers

that serve pages to users are host nodes. The nodes that connect the networks in between are gateways. These are gateway nodes.

Types Gateway• There are two main types of gateways: unidirectional gateways and

bidirectional gateways.• Unidirectional gateways allow alerts to flow in only one

direction. Changes made in the source Object Server are replicated in the destination Object Server or application, but changes made in the destination Object Server or application are not replicated in the source Object Server. Unidirectional gateways can be considered as archiving tools.• Bidirectional gateways allow alerts to flow from the source

Object Server to the target Object Server or application, and also allow feedback to the source Object Server. In a bidirectional gateway configuration, changes made to the contents of a source Object Server are replicated in a destination Object Server or application, and the destination Object Server or application replicates its alerts in the source Object Server. Bidirectional gateways can be considered as synchronization tools.

ConclusionSo in this section we studied about Routers Bridges Repeaters Hubs Switch Gateway

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