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Tuesday, June 14th, 2011Microsoft Ieee
LAN Network Protocols - Ethernet, STP, Fiber
This article discusses the campus protocols found in almost all enterprise networks today including spanning tree protocol, ethernet and gigabit optical fiber with a description of the current specifications and process.
Spanning Tree Protocol
Spanning Tree is an algorithm that runs on Layer 2 campus switches for preventing Layer 2 loops and broadcast storms on a network with at least 2 switches or bridges. The algorithm determines what ports at each switch or bridge must be blocked to create a loop free topology. Primary specifications are IEEE and 802.1d. The spanning tree port states are listening, learning, blocking, forwarding or disabled. Each group of switches will elect a root bridge as part of determining what switch ports must be blocked for a loop free topology. The root bridge is selected by default as the switch with the lowest priority (MAC address). Root bridge selection can be changed with the bridge priority command. It is important to consider your campus switch design and if necessary modify the root bridge selection for performance.
Newer switches that use VLAN's run one spanning tree instance per VLAN. This is important to note since Layer 2 loops occur per VLAN or segment. This allows a switch with dual connections to the same switch or different switches to load balance across those links without the concern of creating a broadcast storm. This is accomplished by assigning two VLAN's to a switch that has dual links to different campus core switches. Each link is configured to forward traffic from one VLAN and block it on the second link. For instance, consider a switch that is assigned 24 ports to VLAN 10 and 24 ports to VLAN 20 and a supervisor engine with 2 Gigabit ports that connect to different core switches. VLAN 10 is assigned to port A and VLAN 20 to port B. If traffic from VLAN 10 were allowed on port B as well, you would have a loop since traffic could leave on port A and return on port B assuming there is a trunk connection between the campus core switches.
Ethernet
This is the most popular campus data link protocol running today. The primary specifications today are 10BaseT, 100BaseT, and Gigabit Ethernet. Many networks today are comprised of 10BaseT and 100BaseT from the desktop and server to the campus switch. Gigabit Ethernet is used from switch to switch and building-to-building. 10BaseT is a specification for 10 Mbps over unshielded twisted pair category 3 cable (UTP). The distance from desktop to switch is 100 meters maximum. The 100BaseT specification is the same except the speed is 100 Mbps over unshielded twisted UTP) pair category 5 cable. Gigabit is a specification for 1000 Mbps across Fiber, STP and UTP cabling. Ethernet uses CSMA/CD as a method of dealing with collisions when two desktops are sending data simultaneously. Both workstations wait for a specified and different length of time before attempting re-transmission. The maximum packet size or MTU of an Ethernet packet is 1518 Bytes.
Optical Fiber Technologies
Gigabit Ethernet uses Multi-Mode Fiber (MMF) and Single Mode Fiber (SMF) for data transmission. Single Mode Fiber uses only one mode of light to travel across the fiber strand using a laser as the light source. Multimode allows for many modes of light to travel across the fiber strand at different angles using an LED as a light source. Modal dispersion results from different light modes transmitted across a fiber strand. The result is that Single Mode Fiber is higher bandwidth and transmits across greater distances. Multi-Mode Fiber is supported with 62.5 micron and 50 micron diameter fibers. The 50-micron fiber will transport across longer distances than 62.5 micron fiber. Multi Mode Fiber uses Short Wave Lasers (SX) and Long Wave Lasers (LX) for Gigabit transmission. Single Mode Fiber is supported with a 9 micron diameter fiber core. It uses long wave lasers to send data between buildings that are 10 kilometers apart.
Shaun Hummel is author of Network Planning and Design Guide available at amazon.com and CiscoDesignBooks.com featuring Networking Books, eBooks, Certifications, Articles and Design Tools.
About the Author
Shaun Hummel, CCNP, is a Senior Network Engineer with 11 years experience in enterprise network planning, design, and implementation. He has worked for various private and public companies in Canada and the United States improving infrastructure, security, and management. He has written Network Planning and Design Guide, Cisco Wireless Network Design Guide and Network Assessment Guide. http://www.ciscodesignbooks.com
On scale between 0-10 how good is my computer?
Microsoft Windows: Vista Premium
3 Gigabytes of DDR2 Ram
225Gb Internal Harddrive
298Gb External Harddrive
3.0Ghz Hyperthreading Procesoor 2 cores Pentium 4
GeForce 7900 256mb
Dvd Burner
Cd Player
Hp Invent
3 Ieee Firewall ports
its a 6.5, cuz your processor is a pentium 4, dual cores are better and more in fashion these days, and your graphics card is a couple of years old. Other than that your RAM is quite good and so is your Hard disk
Microsoft Ieee
Hong-Jiang Zhang receives 2009 IEEE Computer Society Technical Achievement Award
About Microsoft Windows 2000 Help and Support Features
Microsoft Windows 2000 is a computer Operating System, which was developed by Microsoft on February 2000. The Windows 2000 is used for business desktop, notebook computer and server as well. The Microsoft Operating System version windows operating system 2000 has four editions according to the user specific needs and requirements which are Windows 2000 Professional, Windows 2000 Server, Windows 2000 Advanced Server and Windows 2000 Datacenter Server.
The Operating System Windows 2000 is based on the Windows NT Kernel which is also referred to as a NT 5.0. The operating system includes advanced features as well as had overall better support for computer hardware. It’s full version comes around at a price of 900$ and higher, but if you have a Windows Operating System prior to this one you can go for the upgradation version which just costs only 500$.
It supports Intel Pentium 133 MHz or high processor. You can install it easily if you have just 256MB of RAM.Windows 2000 introduced may of new advanced feature rather than it previous version, some important significant feature of Windows 2000 Operating System are:-
1. It Supported FAT16, FAT32 and NTFS.
2. It gives you increased uptime for the computer system and significantly straight Operating system reboot scenarios.
3. Windows 2000 operating system first time introduced the Microsoft Management Console (MMC) tool, which is very useful to create, and open administrative tolls which is a handy one to perform windows technical support. This is also called MMC Console.
4. Enhanced Windows Installer service, which tracks all programs and applications and recognizes installation draw back error and replaces missing components.
5. It support File Encryption process, Encrypted file system protects your sensitive data during the transmission over the network.
6. Also support Virtual Private Networking (VPN). It is a concept of network communication which gives you more security and secure your private local area network from public Internet. It gives you multilingual user working platform to work and allow user interface to switch based for logon to computer.
7. Windows 2000 also support plug and play universal serial bus (USB) and IEEE 1394 for greater band width devices.
8. The system File Checker (SFC) also comes with Windows 2000 Operating System. SFC scans your all operating system file and verifies whether they are singed or not by Microsoft and works in conjunction with the file protection mechanism. It is a command line utility of Windows 2000 OS.
The Recovery Console:
When you are facing the booting problem with windows 2000 Operating System, then it is very useful for windows repair. Recovery console run outside the installed copy of Windows and is used to perform windows support and maintenance tasks. It is just a simple command line interface, to check and fix your hard drive errors, repair all boot information and replace all corrupted booting files with fresh copies from the Operating System Disk.
About the Author
Joseph John is a technical expert with iYogi. iYogi a Computer, computer optimization and technical support vendor is the winner of Red Herring Top 100 Award, helps. iYogi provides computer help, windows vista repair, computer support, Microsoft support, dell support, computer repair, computer tech support etc. by Microsoft Certified Technician.
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