Router

Router (computing):
A router is a networking device, commonly specialized hardware, that forwards data packets between computer networks. This creates an overlay inter network, as a router is connected to two or more data lines from different networks. When a data packet comes in one of the lines, the router reads the address information in the packet to determine its ultimate destination. Then, using information in its routing table or routing policy, it directs the packet to the next network on its journey. Routers perform the "traffic directing" functions on the Internet. A data packet is typically forwarded from one router to another through the networks that constitute the inter network until it reaches its destination node.

The most familiar type of routers are home and small office routers that simply pass data, such as web pages, email, IM, and videos between the home computers and the Internet. An example of a router would be the owner's cable or DSL router, which connects to the Internet through an ISP. More sophisticated routers, such as enterprise routers, connect large business or ISP networks up to the powerful core routers that forward data at high speed along the optical fiber lines of the Internet backbone. Though routers are typically dedicated hardware devices, use of software-based routers has grown increasingly common.

Routing is often confused with bridging, which performs a similar function. The principal difference between the two is that bridging occurs at a lower level and is therefore more of a hardware function whereas routing occurs at a higher level where the software component is more important. And because routing occurs at a higher level, it can perform more complex analysis to determine the optimal path for the packet.

Types of Routing Protocols 

Table 3-1 showed how routing protocols can be classified according to various characteristics. This section gives an overview of the most common IP routing protocols. Most of these routing protocols will be examined in detail in other chapters. For now, this section gives a very brief overview of each protocol.

Classifying Routing Protocols 

Routing protocols can be classified into different groups according to their characteristics. Specifically, routing protocols can be classified by their:

Purpose: Interior Gateway Protocol (IGP) or Exterior Gateway Protocol (EGP)
Operation: Distance vector protocol, link-state protocol, or path-vector protocol
Behavior: Classful (legacy) or classless protocol
For example, IPv4 routing protocols are classified as follows:

RIPv1 (legacy): IGP, distance vector, classful protocol
IGRP (legacy): IGP, distance vector, classful protocol developed by Cisco (deprecated from 12.2 IOS and later)
RIPv2: IGP, distance vector, classless protocol
EIGRP: IGP, distance vector, classless protocol developed by Cisco
OSPF: IGP, link-state, classless protocol
IS-IS: IGP, link-state, classless protocol
BGP: EGP, path-vector, classless protocol

The data networks that we use in our everyday lives to learn, play, and work range from small, local networks to large, global inter networks. At home, a user may have a router and two or more computers. At work, an organization may have multiple routers and switches servicing the data communication needs of hundreds or even thousands of PCs.

Routers forward packets by using information in the routing table. Routes to remote networks can be learned by the router in two ways: static routes and dynamic routes.

In a large network with numerous networks and subnets , configuring and maintaining static routes between these networks requires a great deal of administrative and operational overhead. This operational overhead is especially cumbersome when changes to the network occur, such as a down link or implementing a new subnet. Implementing dynamic routing protocols can ease the burden of configuration and maintenance tasks and give the network scalability.

This introduces dynamic routing protocols. It explores the benefits of using dynamic routing protocols, how different routing protocols are classified, and the metrics routing protocols use to determine the best path for network traffic. Other topics covered in this chapter include the characteristics of dynamic routing protocols and how the various routing protocols differ. Network professionals must understand the different routing protocols available in order to make informed decisions about when to use static or dynamic routing. They also need to know which dynamic routing protocol is most appropriate in a particular network environment.

I LOVE MY MOM........!

        A Poor Couple lived in a Small Village in India.They had only 1 Son.They gave him the Best Education.Son Graduated as an Engineer in the nearby CityEventually He got Married to a Rich Girl.Initially, They Lived with His Parents in the Village.Soon the Wife got Tired of Village Life & Persuaded Her Husband to Move to the City Leaving His Old Parents in the Village.As Time went,the Husband saw an Ad in the Newspaper about a Job Vacancy in U.S.He was Successful & Lived in U.S for 20 Years with His Wife.Regularly, He used to Send Money to His ParentsEventually with Time, He Stopped & Forgot about His Parents whether they ever Existed.Every Day He Pray & Immediately after each Prayer He used to see Someone telling Him in a Dream that his Prayer is not Accepted.One Day, He Related this Story to a 'Pious Aalim' who Advised Him to go Back to India to Visit His Parents.The Man Flew to India & Reached the Boundary of His Village.Everything was Changed over there.He could not Find His House.So He asked to the Head of the Village about the Whereabouts of His Parents.The Head of the Village directed Him to a House & said: "In this House, Lives an Old Blind Lady who Lost Her Husband a Few Months Ago. She has a Son who Migrated to US 20 Years back & Never came Back again. What an Unfortunate Man." Son enters that Home & Finds His Mother on the Bed.He Tip-Toed as He did not want to Wake Her up.He hears His Mother Whispering or Mumbling Something.He gets Closer to Hear His Mothers Voice.This is what His Mother was Saying: "God ! I am now Very Old & Blind.My Husband just Died.There is no One to Lower Me in My Grave when I Die. So please Send My Son to Fullfill My Last Wish". This is the Ending of a Story where the Prayer of a Mother is Accepted. 

                                            A Human Body can Bear only 45 Del (units) of Pain. But at the Time of Giving Birth, A Mother feels upto 57 Del (units) of Pain. This is similar to 20 Bones getting Fractured, all at the Same Time.This is just to tell U the extent, to which a Mother Loves Her Child. So, Love Ur Mom till the End of Ur Life.The Lady with whom U Fight almost Everyday, Suffered so much Pain just to give U a Beautiful Life.

The Beautiful Lines........

A good leader can engage in a debate frankly and thoroughly, knowing that at the end she/he and the other side must be closer, and thus emerge stronger. And you don't have that idea when you are arrogant, superficial, and uninformed.

CO-INCIDENCE OF LIFE

1.LIFE has 4 letters so does DEAD.

2.HATE  has 4 letters so does LOVE.

3.ENEMIES  has 7 letters so does FRIENDS.

4.LYING  has 5 letters so does TRUTH.

5.HURT  has 4 letters so does HEAL.

6.NEGATIVE  has 8 letters so does POSITIVE.

7.FAILURE  has 7 letters so does SUCCESS.

8.BELOW  has 5 letters so does ABOVE.

9.CRY  has 3 letters so does JOY.

10.ANGER  has 5 letters so does HAPPY.

11.RIGHT  has 5 letters so does WRONG.

12.RICH  has 4 letters so does POOR.

13.FAIL  has 4 letters so does PASS.

14.KNOWLEDGE  has 9 letters so does IGNORANCE.

15.CHURCH has 6 letters so does MOSQUE and TEMPLE.

A Light-Weight and Scalable Network Profiling System

• Long-term network monitoring in high-speed networks requires new ways for collecting, storing and analyzing flow-based network traffic information. A project at the IBM Zurich Research Laboratory looked at alternatives to the conventional flow-based network profiling approach with the objective of improved scalability for high flow rates. The result is a light-weight and scalable network profiling system for NetFlow and IPFIX that is based on a novel time series aggregation database.
• The continuing trend toward distribution of computing resources increases the need to tightly control the networks providing remote access to resources such as servers, storage and databases. An important means for controlling networks is network performance monitoring and, in particular, network profiling. A typical profiling system collects and analyzes information about the traffic flows passing an observation point in the network, eg, a router or traffic meter. A flow is a sequence of packets with common properties (ie, protocol and source/destination addresses/ports).
• In the past, flow-based network profiling has proven to be useful for a number of applications, including network monitoring, billing and planning. To facilitate smooth operation of service access in distributed computing architectures (eg, SANs, computational Grids) the demand for profiling will continue to rise.
• Other network profiling systems have a critical scalability problem regarding the storage, analysis and access of collected profiling information. Indeed, this was the primary motivation for the development of our approach. In high-speed networks with average flow rates of 1,000 flows/s and peak flow rates of as much as 20,000 flows/s, storage for 180 MB/h (3.6 GB/h at peak times) must be provided and maintained. Over longer time periods (ie, months, years), the data accumulates, resulting in an over-loaded system with slow reporting.
Time Series Aggregation Database

• Our profiling approach addresses the scalability problem by using a novel aggregation database (ADB) for time series information. ADB provides a mechanism for efficient incremental storage of primary data values which are associated with time intervals. The database stores data values in groups of circular arrays of decreasing resolution and is, therefore, able to handle large time series data sets with fast access times and limited storage. ADB automatically assures that the array resolution of older data values is lower than the resolution of newer data values. Additionally, great care was taken with the design of ADB in order to reduce memory to disk synchronization and cache the relevant arrays in memory for fast data import and export.
• Array grouping in ADB is efficient for obtaining a sorted view of related parameters. This feature is of great importance in our profiling tool for efficiently displaying sorted lists of top protocols, top hosts, top flows, etc.
• ADB has a built-in array allocation optimization which further reduces the storage requirements. If an array is updated with values of progressing intervals, no preceding array space is allocated because it will never be needed. Furthermore, for insertion of new values, array space is only allocated in fixed chunks in order to avoid allocation of potentially unused array space. These optimizations reduce the required storage allocations considerably for only sparsely filled time series data streams. In network profiling, these optimizations are very useful when, for instance, a dynamically assigned IP address is only observed during a certain time period (eg, a week). In this case, space in a monthly array is only allocated around the actual observation period and not for the entire month.



Implementation

• The developed system is the first profiling system we know of that implements the emerging IETF IPFIX standard. As such it supports IPv6 at data and control plane and can receive flow records over SCTP.
• The reports show traffic information in graphs and tables regarding domains, protocols, QoS tags, hosts/servers, individual flows, packet and flow statistics, port/host scans and other networking aspects. The reporting period can be varied over many time scales. Custom zoom reports regarding specific traffic aspects can be generated on demand.
• A typical problem in network profiling systems is that bursts of high flow rates can be caused by observed port or host scans. In these cases, a single packet may be considered a flow since no other proceeding packet will have the same properties with regard to the source/destination addresses and ports. The rate of the flow export can, under extreme circumstances, even exceed the data rate. Unfortunately, bursts of high flow rates can not only provoke flow table overflows at the observation points but may also render the analysis and storage to be no longer able to keep up with the incoming flow information. For these cases, we added an automatic mechanism to our system to aggregate flow records of a port or host scan into a single record.
  The described profiling system, including the aggregation database (ADB), has been developed over the past two years. The system has been installed at a number of IBM locations and is currently being tested at two European ISPs. Snapshots of sample reports are shown in the figure.

What is a Motherboard?

The motherboard serves to connect all of the parts of a computer together. The CPU, memory, hard drives, optical drives, video card, sound card and other ports and expansion cards all connect to the motherboard directly or via cables.

The motherboard is the piece of computer hardware that can be thought of as the "back bone" of the PC.

The Motherboard is Also Known As:

mainboard, mobo (abbreviation), MB (abbreviation), system board, logic board

Important Motherboard Facts:

• Desktop motherboards, cases and power supplies all come in different sizes called form factors. All three must be compatible to work properly together.
• Motherboards vary greatly in respect to the types of components they support. For example, each motherboard supports a single type of CPU and a short list of memory types. Additionally, some video cards, hard drives and other peripherals may not be compatible. The motherboard manufacturer should provide clear guidance on component compatibilities.
•  In laptops and tablets, and increasingly even in desktops, the motherboard often incorporates the functions of the video card and sound card. This helps keep these types of computers small in size.
• In a desktop, the motherboard is mounted inside the case, opposite the most easily accessible side. It is securely attached via small screws through pre-drilled holes.
• The front of the motherboard contains ports that all of the internal components connect to. A single socket/slot houses the CPU. Multiple slots allow for one or more memory modules to be attached. Other ports reside on the motherboard which allow the hard drive and optical drive (and floppy drive if present) to connect via data cables.
• Small wires from the front of the computer case connect to the motherboard to allow the power, reset and LED lights to function. Power from the power supply is delivered to the motherboard by use of a specially designed port.
• Also on the front of the motherboard are a number of peripheral card slots. These slots are where most video cards, sound cards and other expansion cards are connected to the motherboard.
• On the left side of the motherboard (the side that faces the back end of the desktop case) are a number of ports. These ports allow most of the computer's external peripherals to connect such as the monitor, keyboard, mouse, speakers, network cable and more.
• All modern motherboards also include USB ports here, and increasingly other ports like HDMI and FireWire, that allow compatible devices to connect to your computer when you need them - devices like digital cameras, printers, etc.
• The desktop motherboard and case are designed so that when peripheral cards are used, the sides of the cards fit just outside the back end, making their ports available for use.

Computer-integrated Manufacturing

The term "computer-integrated manufacturing" is both a method of manufacturing and the name of a computer-automated system in which individual engineering, production, marketing, and support functions of a manufacturing enterprise are organized. In a CIM system functional areas such as design, analysis, planning, purchasing, cost accounting, inventory control, and distribution are linked through the computer with factory floor functions such as materials handling and management, providing direct control and monitoring of all the operations.

As a method of manufacturing, three components distinguish CIM from other manufacturing methodologies:

• Means for data storage, retrieval, manipulation and presentation;
• Mechanisms for sensing state and modifying processes;
• Algorithms for uniting the data processing component with the sensor/modification component.

CIM is an example of the implementation of information and communication technologies (ICTs) in manufacturing.

CIM implies that there are at least two computers exchanging information, e.g. the controller of an arm robot and a micro-controller of a CNC machine.

Some factors involved when considering a CIM implementation are the production volume, the experience of the company or personnel to make the integration, the level of the integration into the product itself and the integration of the production processes. CIM is most useful where a high level of ICT is used in the company or facility, such as CAD/CAM systems, the availability of process planning and its data.

There are three major challenges to development of a smoothly operating computer-integrated manufacturing system:

• Integration of components from different suppliers: When different machines, such as CNC, conveyors and robots, are using different communications protocols (In the case of AGVs, even differing lengths of time for charging the batteries) may cause problems.

• Data integrity: The higher the degree of automation, the more critical is the integrity of the data used to control the machines. While the CIM system saves on labor of operating the machines, it requires extra human labor in ensuring that there are proper safeguards for the data signals that are used to control the machines.

• Process control: Computers may be used to assist the human operators of the manufacturing facility, but there must always be a competent engineer on hand to handle circumstances which could not be foreseen by the designers of the control software.

• Subsystems in computer-integrated manufacturing:

  A computer-integrated manufacturing system is not the same as a "lights-out" factory, which would run completely independent of human intervention, although it is a big step in that direction. Part of the system involves flexible manufacturing, where the factory can be quickly modified to produce different products, or where the volume of products can be changed quickly with the aid of computers. Some or all of the following subsystems may be found in a CIM operation:
  Computer-aided techniques:
  • CAD (computer-aided design)
  • CAE (computer-aided engineering)
  • CAM (computer-aided manufacturing)
  • CAPP (computer-aided process planning)
  • CAQ (computer-aided quality assurance)
  • PPC (production planning and control)
  • ERP (enterprise resource planning)
  • A business system integrated by a common database.
  Devices and equipment required:
  • CNC, Computer numerical controlled machine tools
  • DNC, Direct numerical control machine tools
  • PLCs, Programmable logic controllers
  • Robotics
  • Computers
  • Software
  • Controllers
  • Networks
  • Interfacing
  • Monitoring equipment
  Technologies:
• FMS, (flexible manufacturing system)
• ASRS, automated storage and retrieval system
• AGV, automated guided vehicle
• Robotics
• Automated conveyance systems
• There are multiple areas of usage:
  • In Industrial and Production engineering
  • In mechanical engineering
  • In electronic design automation (printed circuit board (PCB) and integrated circuit design data for manufacturing)