...The switch in time saves nine One of the proverbs I find most useful in life is the one of Thomas Fuller – a British writer: “A stitch in time saves nine”. It is a well known proverb. It is frequently used in conversation. It passes on from one hand to another like a current coin A stitch in time saves nine” is an idiom, which is a phrase whose symbolic or intended meaning is different from the literal meaning of the words themselves. Literally, it means that a single stitch (to fix a tear in a garment) will avoid having to make many more (nine) to fix a larger tear that it might cause/( A cloth which is torn must be stitched at once for otherwise the torn portion would increase in size and many more stitches would be required.) Figuratively, a little work today (one stitch) can save a lot of work later on (the nine stitches). For example, fixing a tile on the roof can stop the wind and water from getting in and causing a lot of damage to ceilings and so on. Or putting a little oil in the car engine can avoid a ruined engine, a ruined trip and an expensive repair. We must at all times be well prepared for all things. The truth of the proverb will become clear, if we consider a few examples from day to day life. It is early in life that many bad habit is acquired and if the evil habit is not checked then and there, it grows and gives rise to many other evil habits. If a growing child tells lies, he should be at once taken to task so that the habit doesn't take roots,...
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...system) - Brains of the switch, NCP (network control processor) – Mini brains of the switch; ICS (interface controller) – Interface between the NCP and the line modules, Trunk Module – The portion of the switch where the trunk circuit terminates, Line Module - portion of the switch where the individual POTS (plain old telephone lines). 3. Explain the difference between a tandem switch and a class 5 switch. A tandem switch is a class 4switch, its main purpose is to switch trunks, between the toll switch and the local telephone net work ,and between the CLEC regional center class 5 switches, between the ILEC’s end-office class 5 switches, and between operator services toll switches called OSPS’s. A class 5 switch (local) has line modules, trunk modules, interface communications modules, a switch fabric, network switch processors and central switch processors. It is also referred to as an end-office switch because, as it sounds, it sits in the central office. 4. Explain the difference between a tandem switch and a long distance switch. A tandem switch is a class4 switch, its main purpose is to switch trunks, between the toll switch and the local telephone net work, and between the CLEC regional center class 5 switches, between the ILEC’s end-office class 5 switches, and between operator service s toll switches called OSPS’s. A long distance switch routes traffic through the long distance network. The types of interfaces that terminate on a long distance switch are inter machine trunks...
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...the MIT AI Lab's PDP-10, and noticed a little switch glued to the frame of one cabinet. It was obviously a homebrew job, added by one of the lab's hardware hackers (no one knows who). You don't touch an unknown switch on a computer without knowing what it does, because you might crash the computer. The switch was labeled in a most unhelpful way. It had two positions, and scrawled in pencil on the metal switch body were the words ‘magic' and ‘more magic'. The switch was in the ‘more magic' position. I called another hacker over to look at it. He had never seen the switch before either. Closer examination revealed that the switch had only one wire running to it! The other end of the wire did disappear into the maze of wires inside the computer, but it's a basic fact of electricity that a switch can't do anything unless there are two wires connected to it. This switch had a wire connected on one side and no wire on its other side. It was clear that this switch was someone's idea of a silly joke. Convinced by our reasoning that the switch was inoperative, we flipped it. The computer instantly crashed. Imagine our utter astonishment. We wrote it off as coincidence, but nevertheless restored the switch to the ‘more magic’ position before reviving the computer. A year later, I told this story to yet another hacker, David Moon as I recall. He clearly doubted my sanity, or suspected me of a supernatural belief in the power of this switch, or perhaps thought I was fooling him with a...
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...TMC1254 Communication and Computer Network Semester 2 2013/2014 Switching 1 Learning Unit Objectives • Understand the concept of switching. • Understand and able to differentiate between different types of switching. 2 • How many connection per device? 3 Introduction • A network is a set of connected devices • How to connect them for communication? – Using mesh topology but wasteful – Used switching • Switched network consists of a series of interlinked nodes, called switches (temporary connection btw 2 or > devices) 4 Switched network 3 Simple Switching Network 6 Taxonomy of switched networks 7 Circuit Switched Networks Three Phases Efficiency Delay 8 9 CIRCUIT-SWITCHED NETWORKS • consists of a set of switches connected by physical links. • Connection between two stations is a dedicated path made of one or more links. – However, each connection uses only one dedicated channel on each link. – Each link is normally divided into n channels by using FDM or TDM. 10 How circuit-switched network works? • Consist of three phases: 1. Setup phase: – When end system A needs to communicate with end system M, system A need to request a connection to M that must accepted by all switches as well as by M – Allocation of resources as needed 2. Data transfer: data is transferred from node to node. 3. Teardown: After all data have been transferred, the circuits are torn down. – Circuit is terminated, de-allocation...
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...Configuring Basic Switch Settings Topology Addressing Table Device | Interface | IP Address | Subnet Mask | Default Gateway | S1 | VLAN 99 | 192.168.1.2 | 255.255.255.0 | 192.168.1.1 | PC-A | NIC | 192.168.1.10 | 255.255.255.0 | 192.168.1.1 | Objectives Part 1: Cable the Network and Verify the Default Switch Configuration Part 2: Configure Basic Network Device Settings Configure basic switch settings. Configure the PC IP address. Part 3: Verify and Test Network Connectivity Display device configuration. Test end-to-end connectivity with ping. Test remote management capabilities with Telnet. Save the switch running configuration file. Part 4: Manage the MAC Address Table Record the MAC address of the host. Determine the MAC addresses that the switch has learned. List the show mac address-table command options. Set up a static MAC address. Background / Scenario Cisco switches can be configured with a special IP address known as Switched Virtual Interface (SVI). The SVI or management address can be used for remote access to the switch to display or configure settings. If the VLAN 1 SVI is assigned an IP address, by default, all ports in VLAN 1 have access to the SVI management IP address. In this lab, you will build a simple topology using Ethernet LAN cabling and access a Cisco switch using the console and remote access methods. You will examine default switch configurations before configuring basic switch settings. These basic switch settings include...
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...Configuring Basic Switch Settings Topology Addressing Table Device Interface IP Address Subnet Mask Default Gateway S1 VLAN 99 192.168.1.2 255.255.255.0 192.168.1.1 PC-A NIC 192.168.1.10 255.255.255.0 192.168.1.1 Objectives Part 1: Cable the Network and Verify the Default Switch Configuration Part 2: Configure Basic Network Device Settings Configure basic switch settings. Configure the PC IP address. Part 3: Verify and Test Network Connectivity Display device configuration. Test end-to-end connectivity with ping. Test remote management capabilities with Telnet. Save the switch running configuration file. Part 4: Manage the MAC Address Table Record the MAC address of the host. Determine the MAC addresses that the switch has learned. List the show mac address-table command options. Set up a static MAC address. Background / Scenario Cisco switches can be configured with a special IP address known as Switched Virtual Interface (SVI). The SVI or management address can be used for remote access to the switch to display or configure settings. If the VLAN 1 SVI is assigned an IP address, by default, all ports in VLAN 1 have access to the SVI management IP address. In this lab, you will build a simple topology using Ethernet LAN cabling and access a Cisco switch using the console and remote access methods. You will examine default switch configurations before configuring basic switch settings. These basic switch settings include device...
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...206 quizes Grading Summary These are the automatically computed results of your exam. Grades for essay questions, and comments from your instructor, are in the "Details" section below. | Date Taken: | 11/9/2012 | Time Spent: | 13 min , 51 secs | Points Received: | 25 / 50 (50%) | | Question Type: | # Of Questions: | # Correct: | Multiple Choice | 10 | 5 | | | Grade Details - All Questions | 1. | Question : | (TCO 1) Classifying and prioritizing traffic based on type of data. | | | Student Answer: | | Quality of Service (QoS) | | | | Redundancy | | | | Scalability | | | | VLANs | | Instructor Explanation: | Chapter 1 | | | | Points Received: | 0 of 5 | | Comments: | | | | 2. | Question : | (TCO 1) What options are available for switching hardware? | | | Student Answer: | | Modular, fixed, stack | | | | Fixed, daisy-chained, trunked | | | | Isolated, modular, stack | | | | Modular, fixed, dynamic | | Instructor Explanation: | Chapter 1 | | | | Points Received: | 5 of 5 | | Comments: | | | | 3. | Question : | (TCO 1) At what layer(s) of the hierarchical model would you typically find Cisco’s 6500 series chassis? | | | Student Answer: | | Access | | | | Core | | | | C & D | | | | Distribution | | Instructor Explanation: | Chapter 1 | | | | Points Received: | 0 of 5 | | Comments: | | ...
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...controls switching • ICS –(Interface control system) interface between the NCP and the trunks • Trunk module – portion of the switch where the trunks terminate • Line module – portion of the switch where the individual POTS line terminate 3. Explain the difference between a tandem switch and a class 5 switch. Tandem switches route between trunks to the class 5 switches where as the class 5 switches control thousands of lines 4. Explain the difference between a tandem switch and a long distance switch. Tandem switches route to class 5 local trunks where long distance switches find available trunks in different regions 5. Explain the difference between a long distance switch and an international switch. The long distance switch finds trunks in a different region whereas the international switches find switches in other countries and then performs a signal conversion for compatability. 6. Explain how a class 5 switch routes a call traveling between two lines that are served from the same switch. Routes from the end office to the tandem which would connect both through the class 5 switch which can handle the load of thousands of subscriber lines. 7. Explain how a call is routed between an end-office switch and the local tandem switch. Routes from one end office to a LD switch then to another LD switch which is connected to the Tandem switch. 10. Why do business customers purchase private branch exchanges. These are used in situations where the amount of processing...
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...EMI Issues in Modern Power Electronic Systems Firuz Zare, Queensland University of Technology, Brisbane, QLD, Australia, Email: f.zare@qut.edu.au Abstract—Electromagnetic compatibility of power electronic systems becomes an engineering discipline and it should be considered at the beginning stage of a design. Thus, a power electronics design becomes more complex and challenging and it requires a good communication between EMI and Power electronics experts. Three major issues in designing a power electronic system are Losses, EMI and Harmonics. These issues affect system cost, size, efficiency and quality and it is a tradeoff between these factors when we design a power converter. Main aims in modern power electronic systems are to deliver the power with maximum efficiency, minimum cost and weight in an integrated circuit. Power electronics has a significant role in different industries when power processing is required such as in computers, telecommunications, motor drives, cars and alternative energy systems. In general, circuit elements in most electrical systems are resistors, capacitors, magnetic elements and transistors as shown in Fig. 2. Some of these components may be used in low or high power systems. In most electronic circuits in which efficiency is not a main concern, circuit elements consist of resistors, capacitors and transistors. It is difficult to include magnetic elements into integrated circuits as they are large in size compared to capacitors and resistors...
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...Which component is better between a Hub and a Switch? A very broad question that can be answered by asking and answering questions like: Will a hub support more bandwidth with multiple pc’s or will a switch? How many connections can each have at a time and can they be stacked? Which is more cost effective? Without these questions you cannot honestly answer the main question. When it comes to bandwidth allocations and how they are supported the switch is generally hands down the better choice. While hubs do support the same amount of bandwidth they share it between machines while a switch dedicates full bandwidth to each machine. To explain hubs better let’s say I have computers A, B, & C. I am on the 'A' computer and wish to send a file to the 'B' computer. C will hear all the talking but will not take action into receiving the file. Each piece of network data that C receives must be inspected by C and after C realizes that it is not for it the data is ignored. So the total bandwidth is shared among the computers. Whatever bandwidth A and B are not using for this file transfer is left for C to use. To sum it up hubs distribute all of the data they receive to all the network devices they are connected to. This is a highly inefficient use of your network bandwidth. However, there is no processing delay created by the hub because the hub, by definition, does no processing. A switch can be considered a 'smart' hub. It will actively look at the traffic it receives and based...
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...switching, you must first ask yourself two important questions: First, how can you tell if your network will benefit from switching? Second, how do you add switches to your network design to provide the most benefit? This tutorial is written to answer these questions. Along the way, we’ll describe how switches work, and how they can both harm and benefit your networking strategy. We’ll also discuss different network types, so you can profile your network and gauge the potential benefit of network switching for your environment. What is a Switch? Switches occupy the same place in the network as hubs. Unlike hubs, switches examine each packet and process it accordingly rather than simply repeating the signal to all ports. Switches map the Ethernet addresses of the nodes residing on each network segment and then allow only the necessary traffic to pass through the switch. When a packet is received by the switch, the switch examines the destination and source hardware addresses and compares them to a table of network segments and addresses. If the segments are the same, the packet is dropped or “filtered”; if the segments are different, then the packet is “forwarded” to the proper segment. Additionally, switches prevent bad or misaligned packets from spreading by not forwarding them. Filtering packets and regenerating forwarded packets enables switching technology to split a network into separate collision domains. The regeneration of packets allows for greater...
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...Transfer power dissipation from the switch to a resistor or a useful load Reduce total losses due to switching Reduce EMI by damping voltage and current ringing There are many different kinds of snubbers but the two most common ones are the resistorcapacitor (RC) damping network and the resistor-capacitor-diode (RCD) turn-off snubber. This application note will show you how to design these two snubbers. Switching waveforms Before getting into the design of snubbers it is important to understand the waveforms which occur naturally in power circuits. These provide both the motivation for using snubbers and the information needed for their design. There are many different types of circuits used in power converters, motor drives, lamp ballasts and other devices. Fortunately all of these different circuits have a common network and waveforms associated with the switches. Figure 1 shows four widely used circuits. All of these circuits, and in fact most power electronics circuits, have within them the same switch-diodeinductor network shown within the dotted lines. The behavior of this network is the same in all these circuits which means that we only have to solve the snubber design problem for one circuit to apply it to all of the others. This tremendously simplifies the problem and allows generalized snubber design techniques. A typical boost converter is shown in figure 2A. For snubber design we are concerned with circuit behavior during the switch...
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...two Ethernet LANs Fast Ethernet - 100-Mbps 1995 Gigabit Ethernet - 1000-Mbps late 90’s MAC address - A media access control address (MAC address) is a unique identifier assigned to network interfaces for communications on the physical network segment Autonegotiation - An Ethernet procedure by which two connected devices choose common transmission parameters, such as speed, duplex mode, and flow control. MAC address table - a table which lists which MAC address is connected to which port Ethernet frame – payload of an Ethernet packet Wired LAN – a local area network that is hard wired using Ethernet cables Wireless LAN – local area network that is wireless using the 802.11 standard Star topology - network consists of one central switch, hub or computer, which acts as a conduit to transmit messages. 10BASE-T - Twisted-pair cables for the physical layer of an Ethernet computer network. 100BASE-T - A networking standard that supports data transfer rates up to 100 Mbps, fast Ethernet 1000BASE-T - 1000BASE-T is Gigabit Ethernet (1 gigabit is 1000 megabits per second) on copper cables 10GBASE-T - 10 Gigabit Ethernet, 10 Gbit/s connections Metro Ethernet - Type of WAN service Token Ring - Type of LAN technology that uses a special three-byte frame called a token that travels around the ring. Token-possession grants the possessor permission to transmit on the medium. LAN Edge – Local area network that has the ability to distribute data to multiple users connected to the...
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...-qo[-|+] switch. It allows to open the archive contents in graphical interface faster. This version provides better update peformance for archives containing both quick open information and service records, such as NTFS file security. Also default parameters of quick open information are optimized to achieve faster open time for such archives. 2. Bugs fixed: a) "Test" command could erroneously report damaged data in valid recovery record if only a part of files in RAR 5.0 archive was tested. It did not happen if entire archive contents was tested; b) "Test" command erroneously reported errors when verifying RAR 4.x Unix symbolic links. Version 5.00 1. New RAR 5.0 archiving format. You can use -ma command line switch to create RAR 5.0 archives. By default RAR creates archives in 4.x format. 2. Changes in RAR 5.0 compression algorithm: a) maximum compression dictionary size is increased up to 1 GB in 64 bit RAR. 32 bit RAR version can use up to 256 MB dictionary when creating an archive. Both 32 bit and 64 bit versions can unpack archives with any dictionary size, including 1 GB; b) default dictionary size for RAR 5.0 is 32 MB, typically resulting in higher compression ratio and lower speed than RAR 4.x 4 MB. You can use -md switch to change this value; c) -md switch syntax...
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...Clap switch December 18, 2010 - Basic Electronics, LDR Engineering, MINI Breadboard - Tagged: 555, clap switch - 184 comments READ ABOUT RECENTLY PUBLISHED CLAP-SWITCH CHECK “CLAP-SWITCH WITH TOGGLE FEATURE”. In order to make a clap switch, we have to combine the touch sensor(monostable mode of 555 and the transistorized dark sensor circuits. Whenever there is loud sound produced near the electret condenser mic, pin 2 of 555 gets triggered and it switches on the LED D1. The LED remains on for a definite time determined by R1 and C1. We can adjust the sensitivity of the circuit using a variable resistor in place of fixed resistor R5. You can check the circuit with 1K or 10K. - See more at: http://www.buildcircuit.com/clap-switch2/#sthash.XShIrDIv.dpuf The schematic of clap switch: You can see the steps for making clap switch on the video given below. - See more at: http://www.buildcircuit.com/clap-switch2/#sthash.XShIrDIv.dpuf If you want to glow a bulb operating at 220V, use the following schematic: clap switch operating 220V bulb Before you make this project, read carefully about RELAYS: http://www.buildcircuit.com/how-to-use-a-relay/ If you are not confident at making circuits, don’t work with 220V, it can be dangerous and harm you. READ ABOUT RECENTLY PUBLISHED CLAP SWITCH CHECK “CLAP SWITCH WITH TOGGLE FEATURE”. - See more at: http://www.buildcircuit.com/clap-switch2/#sthash.XShIrDIv.dpuf As what i understand, this clap switch can detect false triggering...
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