Routing Tables

A routing table is an electronic document that stores the routes to the various nodes in a computer network. The nodes may be any kind of electronic device connected to the network. The Routing Table is usually stored in a router or networked computer in the form of a database or file. When data needs to be sent from one node to another on the network, the routing table is referred to in order to find the best possible route for the transfer of information.

Almost all computers and network devices connected to Internet use routing tables to compute the next hop for a packet. It is electronic table that is stored in a router or a networked computer. The routing table stores the routes (and in some cases, metrics associated with those routes) to particular network destinations. This information contains the topology of the network immediately around it. The construction of routing table is the primary goal of routing protocols and static routes.

Routing tables can generally be maintained manually when the network is small and static. The routing tables for all static network devices never change unless and until the administrator of the network changes them manually. In dynamic routing, the devices themselves automatically build and maintain their own routing tables. They do this by exchanging information regarding the network topology using routing protocols. This enables the devices in the network to automatically adapt to the changes in the network like device failures and network congestion as and when they occur.

Understand Broadband Router

A broadband router combines the features of a traditional network switch, a firewall, and a DHCP server. Broadband routers are designed for convenience in setting up home networks, particularly for homes with high-speed cable modem or DSL Internet service. A broadband router supports file sharing, Internet connection sharing, and home LAN gaming.

A broadband router follow the Ethernet standard for home networking. Traditional broadband routers required Ethernet cables be run between the router, the broadband modem, and each computer on the home LAN. The newer wireless routers also support broadband Internet access and the Ethernet standard without the need for cabling.

Several manufacturers offer broadband router products to the consumer. Features that differentiate broadband router products include the number and type of ports available on the unit for cabling computers, external modems, or other network devices.

Note: Image reference is taken from the answers.com.

Cisco launches super fast router.....

NETWORKING HARDWARE VENDOR Cisco announced a router that it thinks could change the world wide web for evermore.The company said its glorious CRS-3 carrier-grade router is designed to serve as the foundation of the next-generation Internet, as it can manage speeds of up to 322 Terabits per second.

Just so the great unwashed know, that is fast enough to transmit the entire printed collection of the US Library of Congress in one second, or the bandwidth required for every man, woman and child in China to make a video call, simultaneously. Every movie ever created could be streamed in less than four minutes, Cisco claims.

Of course it is just a router and not the entire world wide web infrastructure, but it has more than 12 times the traffic capacity of anything else out there.Cisco says that it will make Internet and cloud services much more efficient. It mentions that AT&T recently tested the Cisco CRS-3 during the world's first field trial of 100-Gigabit backbone network technology, which took place over AT&T's live network between New Orleans and Miami recently.

The CRS-3 machine will replace the firm's CRS-1 router, which is still one of the most popular and fastest available commercial routers. The CRS-3 is three times faster than the CRS-1.The firm says its latest top of the line carrier-grade router is powered by its Quantumflow Array Processor, which unifies the combined power of six communications processor chips to work as one. This apparently will deliver high service capabilities and processing power. It also will require only a fraction of the power.

Destination and Next Hop Addresses

What is the relationship between the destination address in a datagram header and the address of the next hop to which the datagram is forwarded?The Destination IP address field in a datagram contains the address of the Ultimate destination.When a router receives a datagram,the router extracts the destination address D,and uses it to compute the address of the next router to which datagram should be sent,N.Although the datagram is sent directly to address N,the header in the datagram retains destination address D.All routes are computed using IP address.After computing the address of a next hop,N,IP software uses the address binding to translate N to an equivalent hardware address for transmission.

Physical Network Connection With Routers

The basic hardware component used to connect heterogeneous networks is a Router.Physically,routers resembles bridges that means each router is a special purpose hardware system dedicated to the task of interconnecting networks.Like a bridge,a contains a processor and memory as well as a separate I/O interface for each network to which it connects.The network treats a connection to a router, the same as the connection to any other computer.

The most important that you have to kept in your mind about router is that it is not only used to connect two similar technology,it can also be used to connect two different types of network technology. Router can connect two LAN's,a LAN and a WAN,or two WAN's.Furthermore,when a router connects two network in the same general category,the networks do not need to use the same technology.For ex:- A router can connect an Ethernet LAN to a frame relay network.Thus,each cloud represents an arbitrary network technology.On summarizing this whole,we can say that a router is a special purpose system dedicated to the task of interconnecting networks.A router can interconnect networks that use different technologies,including different media,physical addressing schemes or frame formats.

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Goal of Internet

The main goal of internetworking is to provide a universal service across heterogeneous networks.To provide universal service among all computers on an internet,routers must agree to forward information from a source on one network to the specified destination on the other network.The task is complex because as all we know that different frame formats and different addressing schemes are used by different networks.Hence,to overcome this problem protocol software is needed on computers and routers to make universal service possible.The main task of these internet protocols is to overcome the differences in frame formats and physical addresses to make communication possible among networks that use different technologies.
For knowing more about protocols for internetworking you can visit:
http://networkingconcepts4u.blogspot.com/2009/02/protocol-for-internetworking.html

Internet Architecture

With the help of routers it is possible for an organization to choose network technologies appropriate for each need,and to use routers to connect all networks into a single network.As all we know that router is used exactly two connections but commercial routers can connect more than two networks.Thus,a single router could connect any number of networks.However,an organization seldom uses single router to connect all of its networks.There are two main reasons behind it:

1.As all we know that router must forwarded each packet,the processor in given router is insufficient to handle the traffic passing among an arbitrary number of networks.

2.The second reason behind this is redundancy,because redundancy improves reliability.To avoid a single point of failure,protocol software continuously monitors internet connection,and instructs the routers to send traffic long alternative paths when a network or router fails.

Thus,when planning an internet,an organization must choose a design that meet's the organization's need for reliability,capacity and cost.In particular,the exact details of internet topology often depends on the bandwidth of the physical networks,the expected traffic,the organization's reliability requirements,and the cost and performance of available router hardware.