What is single mode fiber?

Single-mode fiber is a type of fiber optic cable through which only one light signal can travel at a time.
Because single-mode fiber is more resistant to attenuation than multi-mode fiber, it can be used in significantly longer cable runs.
The core of a single-mode fiber is normally 9 microns wide. A micron is one millionth of a meter.
Single-mode fiber can support Gigabit Ethernet over distances as long as 10 kilomters.
The opposite of single-mode fiber is multi-mode fiber.

What is Multi-Mode Fiber Cables?

What is Multi-Mode Fiber Cables?
:Multi-mode fiber allows many "modes", or paths, of light to propagate through the fiber optic cable. The relatively large core of a multi-mode fiber allows good coupling from inexpensive LEDs light sources and the use of inexpensive couplers and connectors. Multi-mode fiber typically has a core diameter of 50 to 100 microns. Two types of multi-mode fiber exist with a refractive index that may be "graded" or "stepped". With graded index fiber the index of be "graded" or "stepped". With graded index fiber the index of refraction of the core is lower toward the outside of the core and progressively increases toward the center of the core, thereby reducing modal dispersion of the signal. With stepped index fiber the core is of uniform refractive index with a sharp decrease in the index of refraction at the core-cladding interface. Stepped index multi-mode fibers generally have lower bandwidths than graded index multi-mode fibers. The most popular fiber for networking is the 62.5/125 micron multi-mode fiber. These numbers mean that the core diameter is 62.5 microns and the cladding is 125 microns. Other common sizes are 50/125 and 100/140. The primary advantage of multi-mode fiber over twisted pair cabling is that it supports longer segment lengths. Multi-mode fiber can support segment lengths as long as 2000 meters for 10 and 100 Mbps Ethernet, and 550 meters for 1 Gbps Ethernet. The industry recommends fiber optic cable be considered for distances greater than 295 feet, when electromagnetic interference is a problem or when transmissions bit rates exceed 350 MHz.

The difference between CSMA/CD and CSMA/CA

CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) is a protocol for carrier transmission in 802.11 networks. Unlike CSMA/CD (Carrier Sense Multiple Access/Collision Detect) which deals with transmissions after a collision has occurred, CSMA/CA acts to prevent collisions before they happen.
In CSMA/CA, as soon as a node receives a packet that is to be sent, it checks to be sure the channel is clear (no other node is transmitting at the time). If the channel is clear, then the packet is sent. If the channel is not clear, the node waits for a randomly chosen period of time, and then checks again to see if the channel is clear. This period of time is called the backoff factor, and is counted down by a backoff counter. If the channel is clear when the backoff counter reaches zero, the node transmits the packet. If the channel is not clear when the backoff counter reaches zero, the backoff factor is set again, and the process is repeated.

the patch panel picture front and back

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What is a patch panel?
Think of it as an old fashioned switchboard. A place where network connections are made and often rearranged, guiding the information to the correct destination, each and every time. And since you don't want to change your patch panel every time you upgrade your network, Belkin's built this one to meet the new enhanced Category 5e requirements. This 48 port CAT 5e patch panel is 19 inch rack mountable and supports both 568A and 568B installations. Compatible with both 110 and Krone punch down tools, with angled design that increases bend radius.A panel of network ports contained together, usually within a telecommunications closet, that connects incoming and outgoing lines of a LAN or other communication, electronic or electrical system. In a LAN, the patch panel connects the network's computers to each other and to the outside lines that enable the LAN to connect to the Internet or another WAN. Connections are made with patch cords. The patch panel allows circuits to be arranged and rearranged by plugging and unplugging the patch cords.



What is the different between CSSMA/CD and CSMA/CA?
The main different CSSMA/CD and CSMA/CA? Protocol is what wireless stations don’t transmit immediately but, even if the medium is detected as free, a random *counter* is generated before transmission.While CSSMA/CD uses a time value as backoff, CSSMA/CA uses that is decremented every time the medium is inactive (sensed free) only when the counter reaches 0 the station will starts its transmission.In any in an Ethernet environment, 2 will 2 nodes choose the same backoff time a collision occur and the probability that the 2 will choose the same backoff time again, after the first collision, decreases exponentially.What is IP address?An identifier for a computer or device on a TCP/IP network. Networks using the TCP/IP protocol route messages based on the IP address of the destination. The format of an IP address is a 32-bit numeric address written as four numbers separated by periods. Each number can be zero to 255. For example, 1.160.10.240 could be an IP address.Within an isolated network, you can assign IP addresses at random as long as each one is unique. However, connecting a private network to the Internet requires using registered IP addresses (called Internet addresses) to avoid duplicates.The four numbers in an IP address are used in different ways to identify a particular network and a host on that network. Four regional Internet registries -- ARIN, RIPE NCC, LACNIC and APNIC -- assign Internet addresses from the following three classes.· Class A - supports 16 million hosts on each of 126 networks· Class B - supports 65,000 hosts on each of 16,000 networks· Class C - supports 254 hosts on each of 2 million networksThe number of unassigned Internet addresses is running out, so a new classless scheme called CIDR is gradually replacing the system based on classes A, B, and C and is tied to adoption of IPv6.What is MAC address?In a local area network (LAN) or other network, the MAC (Media Access Control) address is your computer's unique hardware number. (On an Ethernet LAN, it's the same as your Ethernet address.) When you're connected to the Internet from your computer (or host as the Internet protocol thinks of it), a correspondence table relates your IP address to your computer's physical (MAC) address on the LAN.The MAC address is used by the Media Access Control sublayer of the Data-Link Layer (DLC) of telecommunication protocols. There is a different MAC sublayer for each physical device type. The other sublayer level in the DLC layer is the Logical Link Control sublayer.What is the different Client/server?Client/server describes the relationship between two computer programs in which one program, the client, makes a service request from another program, the server, which fulfills the request. Although the client/server idea can be used by programs within a single computer, it is a more important idea in a network. In a network, the client/server model provides a convenient way to interconnect programs that are distributed efficiently across different locations. Computer transactions using the client/server model are very common. For example, to check your bank account from your computer, a client program in your computer forwards your request to a server program at the bank. That program may in turn forward the request to its own client program that sends a request to a database server at another bank computer to retrieve your account balance. The balance is returned back to the bank data client, which in turn serves it back to the client in your personal computer, which displays the information for you.The client/server model has become one of the central ideas of network computing. Most business applications being written today use the client/server model. So does the Internet's main program, TCP/IP. In marketing, the term has been used to distinguish distributed computing by smaller dispersed computers from the "monolithic" centralized computing of mainframe computers. But this distinction has largely disappeared as mainframes and their applications have also turned to the client/server model and become part of network computing.In the usual client/server model, one server, sometimes called a daemon, is activated and awaits client requests. Typically, multiple client programs share the services of a common server program. Both client programs and server programs are often part of a larger program or application. Relative to the Internet, your Web browser is a client program that requests services (the sending of Web pages or files) from a Web server (which technically is called a Hypertext Transport Protocol or HTTP server) in another computer somewhere on the Internet. Similarly, your computer with TCP/IP installed allows you to make client requests for files from File Transfer Protocol (FTP) servers in other computers on the Internet.Other program relationship models included master/slave, with one program being in charge of all other programs, and peer-to-peer, with either of two programs able to initiate a transaction