Networking Ch 2

security

Which of the following is a concern when using peer-to-peer networks?

two computers connected to each other

Which of the following is an example of a LAN?

Please Do Not Throw Sausage Pizza Away

Which of the following mnemonic devices can you use to remember the first letter of the name of each layer of the OSI model in the proper order?

Mesh

Which of the following physical topologies has the least likelihood of having a collision?

Single-mode fiber

Which of the following provides the longest cable run distance?

Fiber-optic

Which type of cable does EMI have the least effect on?

Console cable

Which type of cable should be used to connect to the console port on a router?

DNS Server

Which type of server in your network uses pointer and A records?

Mesh

Which type of topology has the greatest number of physical connections?

reduces gas, high burn temp

Why would a network administrator use plenum-rated cable during an installation? Choose two.

peer to peer

In what type of network are all computers considered equals and do they not share any central authority?

Data Link

Layer 2

Network

Layer 3

Transport

Layer 4

Session

Layer 5

Presentation

Layer 6

Application

Layer 7

LC Fiber Connector

New er style of SFF fiber optic connector pulling ahead of the MT-RJ. Especially popular for use with Fibre-Channel adapters (FCs) and is a standard used for fast strage area networks and ggabit ethernet adapters. It is easier to terminate than MTRJ and has similar advantages. It uses a ceramic insert just as standard sized fiber optic connectors do.

110 Block

Newer type of wiring distribution point - has replaced most phone wire installations and is used for computer networking. On one side, wires are punched down, the other side has RJ-11 for phonr and RJ 45 for network connections. They come in sizes from 25 to 500 wire pair, and some are capable of carrying 1Gbps connections when used with Cat6 cables. However, using Cat 6 with the 110 block is difficult because of the size of the Cat 6 wiring.

Single mode fiber

Nine micron core and typically yellow cables

Hex E

14

Hex F -

15

VPN

Allows for secure encrypted access for remote systems

Physical

Layer 1

Transport

Segmentation of a data stream happens at which layer of the OSI model?

if two hosts are on the same LAN do they need DNS to communicate?

, they don't need a DNS to communicate because they can broadcast to eachother asking for information

MT-RJ Connector

-Keyed for signle polarity -Pre-terminated ends that require no polishing or epoxy -easy to use -smaller than SC and ST connectors -TX and RX strands in one connector

UTP - 2 Categories

1. Two twisted wire pairs (4 wires). Oldest type/only voice grade/isn't rated for data communication. Cat 2 - 4 twisted wire pairs (eight wires). Handles up to 4Mbps with a frequency limitation of 10 MHz, and is now obsolete. Cat 3 - 4 Twisted wire pairs with 3 twists per foot. Handles transmissions up to 16 Mhz. Limited to telecommunication equipment - obsolete for networks. Cat 4 - 4 twisted wire pairs (8) rated for 20MHz. Cat 5e-Four twisted wire pairs rated for 100 Mhz, but capable of handling disturbance on each pair that is caused by transmitting all four pairs at the same time--a feature needed for Gigabit Ethernet. Nothing below 5e should be used in today's netowrk. Cat 6 - 4 twisted wire pares rated for 250 MHz. You would usually use it as a riser cable but if you are installing a brand new network you should use a Cat 6 UTP cable and running fiber runs through the floor. Allows 10GBaseT to run short distances (less than 100 meters.) Cat 6 Augemented - rated for up to 500 MHz with improved cross talk allowing for 10GBaseT to run for up to 100 meters

Data Encapsulation Method

1. User information is converted to data for transmission on the network. 2. Data is converted to segments, and a reliable connection is set up between the transmitting and receiving hosts. 3. Segments are converted to packets or datagrams, and a logical address is placed in the header so each packet can be routed through an internetwork. 4. Packets or datagrams are converted to frames for transmission on the local network. Hardware (Ethernet) addresses are used to uniquely identify hosts on a local network segment. 5. Frames are converted to bits, and a digital encoding and clocking scheme is used. (data, segment, packet, frame, bits)

Hex A - 1010

10

Hex B

11

Hex C

12

10000000

128

Hex D

13

11000000

192 (128+64)

WAN

A network that crosses, local, regional, or international boundaries

1110000

224 (128+64+32)

11110000

240

11111000

248

11111100

252

11111110

254

11111111

255

LAN

A network that is restricted to a small area such as a room, building, or on a floor of a building

wiring standards

568A, 568B, Straight-through, crossover

ethernet

A contention media-access method that allows all hosts on a network to share the same bandwidth of a link. Uses data link and physical layer specs

Host to switch

A cross-over cable is used to connect all of the following except:

CAN

A network comprised of LANs that are in an area owned by the same entity that uses it

Hub

A network device that is used to connect multiple devices together without segmenting a network is a?

CSMA/CD - Carrier Sense Multiple Access with Collission Detection

A protocol that helps devices share the bandwidth evenly without haveing two devics transmit at the same time on the network medium. When a host is going to transmit on a network, t first checks for the presence of a digital signal on the wire. If no other host is transmitting, the host will proceed with its transmission. Then it will constantly monitor the wire to make sure no other hosts begin transmitting. If the host does detect another signal on the wire, it sends out a jam signal that causes all ohsts on the semgent to stop transmitting. Hosts respond by waiting before attempting to retransmit.

Decrease the window size.

A receiving host has failed to receive all the segments that it should acknowledge. What can the host do to improve the reliability of this communication session?

Thin Ethernet (thinnet or 10Base2)

A thin (1/4" diameter)coaxial cable. Thin Ethernet coaxial cable is RG-58, or radio grade 58.

Layer 4

Acknowledgments, sequencing, and flow control are characteristic of which OSI layer?

Small Form Factor (SFF) Connector

Allows more fiber-optic terminations in the same amount of space than its standard-sized counterparts. Two most popular versions include the mchanical transfer registered jack (MT-RJ) and the Local Connector (LC)

Ethernet

An example of a hybrid network is which of the following?

Host

Any network with a TC/IP address

Network

At which layer of the OSI model would you find IP?

Data Link, Physical, Network

At which layers of the OSI model do bridges, hubs, and routers primarily operate, respectively?

1000BaseCX

Balanced, shirlded copper/1000Mbps/25 meters/Uses a special connector, the HSSDC

Connection-Oriented Communication

Before transmitting host sends segments down the model, the senders TCP process contacts the destination's TCP process to establish a connection (virtual circuit). During this "handshake" the two TCP processes also agree on the amount of information that will be sent in either direction before the respective recipient's TCP sends back and acknowledgment. Both hosts' application programs begin by notifying their own operating system that a connection is going to be initiated. The two operating systems communicate by sending messages over the network confirming that the transfer is approved and both sides are ready for it to take place. A connection is then fully established and the data transfer begins. This virtual circuit setup is called overhead. While the info. is transferred, the two machines check in with each other, communicating through their protocol software to ensure all the data is being received properly. The three way handshake is summarized: 1. First "connection agreement" segment is a request for synchronization. 2. The next segments acknowledge the request and establish the rules, or connection parameters, between hosts. These segments request that the receiver's sequencing is synchronized here so that a bidirectional connection is formed. 3. The final segment is also an acknowledgement. It notifies the destination host that the connection agreement has been accepted and that the connection has been established. Data transfer can now begin. (Syn->Syn/ack->ack)

RG-6

Coax cable used for cable television and cable modems

RG-59

Coax cable used for television

10Base5

Coaxial Cable/10Mbps max speed/500 meters per segment/Also called thicknet, this cable type uses vampire taps to connect devices to cable.

RG 6

Coaxial cable used for above 50MHz

RG-59

Coaxial cable used for below 50MHz

10Base2

Coaxial/10Mbps/185 Meters per segment/Also called thinnet, a very popular implementation of Ethernet over coax.

F connector

Connector used to plug coaxial cable into a cable tv.

Twisted Pair Cable

Consists of multiple individually insulated wires that are twited together in pairs. Sometimes a metallic shield is placed around them, hence the name shielded twisted pair (TP). Cable without shielding is UTP.

Coaxial Cable

Contains a center conductor made of copper surrounded by a plastic jacket with a braided shield over it. PVC or FEB (Teflon) covers this metal shield. Teflon covering is referred to as a plenum-rated coating, which is expensive, but often mandated by fire code when cable is hidden in walls and ceilings.

name resolution (host-name to IP-address resolution is usually accomplished usint

DNS (domain name server)

Presentation (Layer 6)

Data encryption, compression and translation services. Presents data and handles processing such as encryption. Presents data to the application layer and is responsible for data translation and code formatting. It is essentially a translator and provides coding and conversion functions.

Flow Control

Data integrity is ensured at the transport layer by maintaining flow control and by allowing users to request reliable data transport between systems. Flow control can limit the amount of data sent by the sender so that it doesn't overflow the buffers in the receiving host, an event that can result in lost data.

Frequency

Defines as the capacity to carry a signal in a cable. each cable type has a specified max frequency that gives you the transmission bandwidth it can handle. Cat 5e is tested to 100 MHz max frequency and can run 1Gbps signals for relatively short distances--that is maxing it out, but it's still good for connecting desktop hosts at high speeds. Cat 6 is a 250 MHz cable that can handle 1Gbps all day long with ease. Cat 6 has more twists and thicker cables so it is best used when connecting floors of a building.

Top 3 Layers (7-5) (Application, presentation, session)

Defines how applications within end stations will communicate with each other and users. Responsible for applications communicating between hosts. Knows nothing about networking or networking addresses.

Bottom 4 Layers (4-1) (Transport, Network, Data Link, Physical)

Defines how data is transmitted from end to end, or how data is transferred through physical media, switches and routers. Determines how to rebuild a data stream from a transmitting host to a destination's host application.

Media Access Control (MAC) (first sublayer of IEEE Ethernet Data Link layer)

Defines how packets are placed on the media.

Fiber Optic Connector ST (straight tip)

Developed by AT&T - uses a BNC attachment making connections hassle free.

Straight Tip (ST)

Developed by AT&T, one of the most widely used connectors for fiber optic cables, uses a BNC attachment similar to thinnet's that make connections and disconnections relatively painless.

Full Duplex

Devices send and receive at the same time

Session (Layer 5)

Dialogue Control - Keeps different applications' data separate. Responsible for setting up, managing and tearing down sessions between presentation layer entities. Coordinates communication between systems and organizes communication into 3 different modes: simplex, half duplex, full duplex.

Transport (Layer 4)

End-to-end data transport services and establishes a logical connection between the sending host and the destination host on an internetwork. Provides reliable or unreliable delivery. Segments and reassembles data from upper layer applications into a data stream. Responsible for providing mechanisms for multiplexing upper-layer applications, establishing virtual connections, and then tearing down virtual circuits. It hides details of any network-dependent information from the higher layers by providing transparent data transfer. Both User Datagram Protocal (unreliable/connectionless) and Transmission Control Protocol (reliable/connection-oriented-acknowledgements, sequencing and flow control is used) work in this layer.

use light impulses

Fiber-optic cable is immune to electromagnetic interference (EMI) and radio frequency interference (RFI) because it:

10BaseFL

Fiber/10Mbps/max transmission distance Varies (ranges from 500 meters to 2K meters)

Application (Layer 7)

File, print, message, database and application services. Provides a user interface. Marks the spot where a user communicates with the computer (technically where the user communicates with the network stack through application processes (APIs) that connect with the computer's operating system.) Also responsible for identifying and establishing the availability of the intended communication partner and determining whether sufficient resources for the intended communication exist. (File transfers, email, remote connection, network management activities, printing, information location, etc.) Networking devices, such as workstations, that run applications are examples of devices on this layer. However, workstations do operate at all layers.

Ethernet Cable Descriptions

Follows this format: N<signaling>X. N refers to the signaling rate in megabits per second, <signaling> stands for the signaling type--either baseband or broadbane, and the X is a unique identifier for a specific Ethernet cabling scheme. 100BaseX: 100 - transmission speed is 100 Mb (megabits), X can mean several things, T is twisted pair.

Data Link (Layer 2)

Framing. Combines packets into bytes and bytes into frames. Provides access to media using MAC addresses. Performs error detection, not correction. Provides the physical transmission of the data and handles error notification, network topology, and flow control. It ensures that messages are delivered to the proper device on a LAN using hardware addresses and translates messages from the Network layer into bits for the physical layer to transmit. Data link layer formats the message into pieces, called a data frame, and adds a customized header containing the destination and source of the hardware address. It is responsible for the unique identification of each device that resides on a local network. This is the only layer that has two sublayers (LLC and MAC). The LLC sublayer is responsible primarily for the multiplexing of Network layer protocols. The MAC sublayer is reponsible for the physical addressign and determining the appropriate time to place data on the network.

568A

Green pair is used for pins 1 and 2 but orange pair is split to pins 3 and 6, separated by the blue pair

Registered Jack Connector RJ 45

Has four pairs

SYN-NAK

Host 1 sent a SYN packet to Host 2. What will host 2 send in response?

2

How many devices can be connected to a full-duplex segment?

1

How many hosts on a half-duplex segment can talk at one time?

4

How many wires are used in UTP during transmission?

copper or fiber?

If data runs are measured in miles use fiber because copper can't give you more than 1500 feet without regenerate the signal. The standards limit UTP to 328 feet. -fiber is higher security -Ethernet running at 10Mbps over fiber optic cable is designated 10BaseFL. The 100 Mbps version is 100BaseFX BaseFL is fiber link BaseFB is fiber backbone BaseFP is fiber passive

Demarc

Last point where your service provider is responsible for service and cabling

1000BaseLX

MMF and SMF/100Mbps/550 meters multimode/2K meters single mode/Uses longer wavelength laser than 1000BaseSX. Uses SC and LC connectors.

1000BaseSX

MMF/1000Mbps/550 meters/Uses SC fiber connectors. Max length depends on fiber size.

100BaseFX

MMF/100Mbps/2K meters/100Mbps Ethernet over fiber optics

10GBaseSR

MMF/10Gbps/300 meters/850 nm laser. Max length depends on fiber size and quality.

10GBaseSW

MMF/10Gbps/300 meters/850nm laser transciever.

Devices that operate at all 7 layers:

Network Management Stations, web and application servers, gateways (not default gateways), network hosts

Application

Of the following, which is the highest layer in the OSI model?

OSI

Open Systems Interconnection - 7 hierarchical layers developed to enable different networks to communicate reliably between different systems.

Physical (Layer 1)

Physical Topology. Moves bits between devices. Specifies voltage, wire speed and pin-out of cables. Sends and receives bits. The physical layer communicates directly with the various types of actual communication media. This layer specifies the electrical, mechanical, procedural, and functional requirements for activating, maintaining and deactivating a physical link between end systems. You identify the interface between the data terminal equipment (DTE) and the data communication equipment (DCE). This layer defines the physical topology (mesh, star, ring, bus).

Straight-Through Cable

Pin 1 connects to pin 1 and pin 2 connects to pin 2, etc.

Rolled Cable

Pin 1 connects to pin 8 and pin 2 connects to pin 7, etc.

Encapsulation

Process of encoding data as it goes down the OSI stack.

Logical Link Control (LLC) (second sublayer of IEEE Ethernet Data Link layer)

Responsible for identifying g network layer protocols and then encapsulating them. An LLC header tells the data link layer what to do with a packet once a frame is received. A host receives a frame and looks in the LLC header to find out where the packet is destines, say, the IP protocol at the Network layer. The LLC can also provide flow control and sequencing of control bits.

Collision Domains

Routers also break up collision domains using Layer 2 (data Link layer) switches.

Broadcast Domain

Routers break up broadcast domains (by default they aren't forwarded through a router.) They provide WAN services.

Network

Routers perform routing at which OSI layer?

Network (Layer 3)

Routing. Provides logical addressing, which routers use for path determination. The network layer also tracks the location of devices on the network and determines the best way to move data, moving traffic between devices that aren't locally attached. Routers (layer 3) are specified at the network layer ad provide the routing services within an internetwork.

subscriber (or square) connector (SC)

SC connectors are latched but are also popular fiber optic connectors.

10GBaseLR

SMF/10Gbps/10Kilometers/1310 nm laser. Max length depends on fiber size and quality.

10GBaseLW

SMF/10Gbps/10Kilometers/typically used with sonet

10GBaseER

SMF/10Gbps/40 Kilometers/1550 nm laser. Max length depends on fiber size and quality.

10GBaseEW

SMF/10Gbps/40 kilometers/1550 nm optical wavelength

Media Converters Examples

Single mode fiber to ethernet, multi mode fiber to ethernet, fiber to coaxial, single mode to multimode fiber

4

TCP and UDP reside at which layer of the OSI model?

568B

The orange pair is pins 1 and 2 and the green pair is pins 3 and 6, again separated by the blue pair.

service provider

The purpose of the demarcation point is to separate the customer from whom?

Route-update packets

These are used to update neighboring routers about the networks connected to all routers within the internetwork. Protocols that send route-update packets are called routing protocols. Common ones include Routing Information Protocol (RIP), RIP v2, Enhanced Interior Gateway Routing Protocol (EIGRP) and Open Shortest Path First (OSPF) Route-update packets are used to help build and maintain routing tables on each router. The routing table includes: 1. network addresses (these are protocol-specific network addresses). A router must maintain a routing table for individual routing protocols because each routing protocol keeps track of a network with a different addressing scheme. 2. Interface This is the exit interface a packet will take when destined for a specific network. 3. Metric: This value equals the distance to the remote network. Different routing protocols use different ways of computing this distance. Some routing protocols (namely RIP) use something called a hop count- the # of routers a packet passs through en route to a remote entwork--where as others use bandwidth, delay of the line, or a tick count (1/8 second)

Devices that operate primarily at the physical layer:

These devices mainly manipulate the physical aspects of a data stream (voltage, signal direction, signal strength). The most popular are NICs, tranceivers, repeaters, and hubs.

Plenum vs Non Plenum

To run cables in the plenum of a building (within walls/ceilings) you must have an approved plenum cable as they can be flammable and act as wicks. Non plenum cables can be used when you aren't running the cable in the plenum-it is cheaper

Layer 3 devices (routers, in this case) provide connections between virtual LANs (VLANs).

True

Routers can provide Layer 2 bridging functions if needed and can simultaneously route through the same interface.

True

Routers can provide Qos (Quality of Service) for specific types of network traffic.

True

False

True or False - A crossover cable is the same thing as a rollover cable.

True

True or False - A hybrid physical topology is a mixing of more than one type of physical topology. Answer:

False

True or False - A peer-to-peer network uses a single database for all user accounts

True

True or False - Fiber-optic cables are immune to electrical interference.

True

True or False - Flow control is used to keep a host being overwhelmed by traffic.

True

True or False - In a fully meshed environment all the devices are connected together.

True

True or False - Servers provide resources to network clients such as file and print services or e-mail.

False

True or False - Straight is one of the physical topology types a network can use.

True

True or False - The "three-way handshake" is also know as SYN, SYN-ACK, SYN".

True

True or False - The OSI model is just a conceptual model and not a standard.

True

True or False - Unshielded Twisted Pair (UTP) is the most commonly used end user network cable today.

Routers can also be referred to a Layer 3 switch

True.

Routers can use access lists, created by an administrator, to control security on the types of packets that are allowed to enter or exit an interface.

True.

Routers use the logical address in a Network layer to determine the next-hot router to forward the packet to.

True.

Routers won't forward any broadcast of multicast packets.

True.

10 BaseT

UTP Cable/10Mbps/100 Meters per segment/One of the most popular network cabling schemes.

Cat 8

UTP cable is rated in the following categories except:

100BaseTX

UTP, STP/100 Mbps/100 meters per segment/Two pairs of Cat 5 UTP

1000BaseT

UTP/1000Mbps/100 meters/4 pairs of Cat5e or higher.

10GBaseT

UTP/10Gpps/100 meters/connects to the network like a Fast Ethernet link using UTP

Data packets

Used to transport user data through the internetwork. Protocols used to support data traffic are called routed protocalls (IP) and IPv6)

DHCP server

Users arrive at the office after a weekend and the hosts that were shutdown over the weekend are restarted but cannot access the LAN or Internet. Hosts that were not shutdown are working fine. Where can the problem be?

Proxy server

Users on your network are saturating your bandwidth because they are using too many non-work related sites. What device would limit the availability of the types of sites that users on a LAN have access to while providing granular control over the traffic between the local LAN and the Internet?

Multi Mode Fiber (MMF)

Uses light to communicate a signal, but the light is dispersed on numerous paths as it travels through the core and is reflected back. Cladding is used to line the core and focus light back onto it. MMF provides high bandwidth at high speeds over medium distances (up to 3,000 feet). It is most often used within a smaller area of one building while SMF can be used between buildings. MMF is available in glass or plastic

Registered Jack Connector RJ 11

Ust to connect tlephones that use four wires, not used for LANs but used for DSL (digital subscriber line) connections.

Single Mode Fiber (SMF) Optic Cable

Very high speed long distance media consisting of one or two strands of glass fiber that carries the signal. LEDs and laser are the light sources used with SMF. The light source is transmitted from end to end and pulsed to create communication. Can be employed to span really long distances because it can transmit data 50 times further than multi-mode fiber at a faster rate. Since the fibers are made from glass installation can be tricky (no crimping or pinching around tight corners).

recognizes frame boundaries

What advantage does a switch have over a hub?

To create more collision domains,To add more bandwidth for users

What are two purposes for segmentation with a bridge?

virtual private network

What does the acronym VPN stand for?

Protocol Data Units (PDUs)

What each layer uses to communicate and exchange information. These hold the control information attached to the data at each layer of the model. They're usually attached to the header in front of the data field but can also be in the trailer, or end, of it.

Routing functions

What is a benefit of a multilayer switch (MLS) over a Layer 2 switch?

VLAN

What is a logical grouping of network users and resources connected to administratively defined ports on a switch?

Assigns IP address to hosts

What is an advantage of using DHCP in a network environment?

Protects LAN

What is the function of a firewall?

Number of light rays

What is the main difference between single-mode fiber (SMF) and multimode fiber (MMF)?

Web cache

What is the most common use for a web proxy?

Breaks up collision domains

What is the primary function of a bridge?

govern the amount of data sent by the sender

What is the purpose of flow control?

Translates human name to IP address

What role does the "A" record in a Domain Name Service (DNS) server have in your network?

Fiber-optic

What type of cable should be used if you need to make a cable run longer than 100 meters?

Fiber-optic

What type of cable transmits lights from end-to-end?

RJ 45

What type of connector does UTP cable typically use?

point to point

What type of topology gives you a direct connection between two routers so that there is one communication path?

Data, segment, packet, frame, bits (dogs sit properly for biscuits)

When data is encapsulated, which is the correct order?

Create VLANs

You have a network with multiple devices and need to have a smaller broadcast domain while working with a tight budget. Which of the following is the best solution?

IDS

You need a device that detect and reports attempts of unauthorized access to your network, identifies suspicious activity, and is best for identifying an attack. Which device should you install?

802.3

Which IEEE standard specifies the protocol for CSMA/CD?

Hub, Repeater

Which Layer 1 devices can be used to enlarge the area covered by a single LAN segment? (Choose two.)

Router

Which device by default does not forward any broadcast or multicast packets?

Switch

Which device creates separate collision domains and a single broadcast domain?

Hub

Which device does not aid in network segmentation?

Switch

Which device is used to segment a network?

Load balancer

Which device should be used if you need to send incoming packets to one or more machines that are hidden behind a single IP address?

NIC

Which is not a common term associated with modems?

Preventing broadcast storms

Which is not an advantage of network segmentation?

Presentation

Which layer of the OSI model is responsible for code and character-set conversion as well as recognizing data formats?

Physical

Which layer of the OSI model is responsible for converting data into signals appropriate for the transmission medium?

Application

Which layer of the OSI model provides a user interface in the form of an entry point for programs to access the network infrastructure?

Hybrid

Which network topology is a combination of two or more types of physical or two or more types of logical topologies?

10,100,1000

Which of the following Ethernet unshielded twisted-pair (UTP) cables types is most commonly used?

ST, SC, LC

Which of the following are fiber-optic connectors? (Select three.)

Buffering,Windowing, Congestion avoidance

Which of the following are types of flow control? (Choose all that apply.)

switch

Which of the following devices can work at both layers 2 and 3 of the OSI model?

Application

You are connected to a server on the Internet and you click on a link on the server and receive a time-out message. What layer could be the cause of this message?

Client Server

You need a network that provides centralized authentication for your users. Which of the following logical topologies should you use?

Star

You need a topology that is scalable to use in your network. Which of the following will you install?

Cat 5

You need to connect two devices on a vertical connect and they need to send voice traffic. Which of the following cable will you use?

568A

You need to crimp on a connector using an RJ-45 connector. Which pin-out configuration would you use to connect a host into a switch?

2

You need to make a 568B cable. How many pairs will you use?

VPN

You want to remotely log into an office computer using remote desktop in a secure manner. Which of the following should you use?

collision domain

a network scenarior wherein one device sends a packet out on a network segment and forces every other device on the same physical network segment to look at it. If two devices on one physical segment transmit at the same time, a collision event (each device's digital signals interfere with another on the wire). Collision events are normally found in a hub environment where each hose segment connects to a hub that represents only one collision domain and one broadcast domain.

Small Form Factor Connectors

allows for more fiber optic terminations in the same amount of space as their standard sized counterparts. The two most popular are the mechanical transfer registered jack (MT-RJ) designed by AMP and the Logical Connector (LC) designed by Lucent.

intermediate distribution frame

another wire frame located in an equipment or telecommunications room. Used to provide greater flexibility

distance

attenuation-the degradation of signal due to the medium itself and the distances signals have tot travel. Any twisted pair cable should have a length of only 328 feet (100 meters)

Which two network media devices can effectively prevent a transmission from propagating throuout the entire network?

bridges and routers.

duplex

communications are either half of full duplex. Difference is whether the communicating devices can talk and listen at the same time.

25 Pair

consists of 25 individual pairs of wires all inside one common insulating jacket. Not generally used for data cablin, just for telephone cabling, backbone and corss-connect cavbles because it reduces the cable clutter. It is often referred to as a feeder cable because it supplies signal to many connected pairs.

backoff algorithm

determine when the colliding stations can retransmit

Media Converters

go from one mode of fiber to another or from fiber to ethernet

avoid emi with copper wires by

keeping copper cales away from all powerful magnetic sources such as electric motors, speakers, amplifiers, fluorescent light ballasts, etc.

demarc extension

last point of responsibility for the ISP, often at the MDF (if large building) but is usually just an RJ45 jack that your channel service unit/data service unit connects into from your router to WAN connections. **Test connectivity on both sides of the demarc to see where the problem is.

Fiber Optic Connector SC (subscriber or square) connector

latched and works with single mode or multimode optical fibers--lasts for about 1k matings.

Parallel

multiple bits are sent at the same time.

another name for a hub

multiport repeater - it sends all data to every host connected to the hub

cross over

occurs when trying to hook a 568A to a 568B. used when connecting two switches to eachother.

smart jack (NID) or NI unit

owned by PSTN and is a special network interface used between the service provider and the internal network

broadcast domain

refers to the set of all devices on a network segment that hear all the broadcasts sent on that segment. It is typically a boundary delimited by physical media such as switches and repeaters but can also referene a logical division o fa network segment where all hosts can reach each other via a data link layer (hardware address) broadcast

T1 cross over cable

required when trying to hook up two CSU/DSUs to each other.

VOIP

requires all eight pins to be connected and use cat5e or cat6 (voice and data)

ethernet at the data link level

responsible for Ethernet addressing (MAC addressing) and is responsible for framing packets received from the network layer and preparing them for transmission on the local network through the Ethernet contention media-access method.

advantages of ethernet

scalable, easy to integrate new technologies such as fast ethernet and gigabit ethernet; simple to implement and troubleshooting is straightforward

Serial Cables

serial means one bit after another is transferred

cable properties

transmission speeds, distance, duplex, noise immunity, frequency

UTP

used in twisted-pair Ethernet (10BaseT, 100BaseTX, 1000BaseTX) networks.

straight-through

used to connect a host to a switch or hub or a router to a switch or hub (router to switch or host to switch)

half duplex

using one wire pair that can only receive or transmit at a time. shares a collision domain; lower throughput than full duplex

full duplex

using two wire pairs that can receive and transmit at the same time typically has a private collision domain with higher effective throughput

RS-232

was a cable standard commony used for serial data signals connecting data terminal equipment and data communications equipment, such as acomputers serial port to external modem. they normally connect to a DB9--they are now replaced with USBs and Firewire

Broadband over Powerline (BPL or Powerline Communication PLC)

will allow you to have more than 500 Mbps for up to 1500 meters

main distribution frame

wiring pint used as a reference point for telephone lines/considered the wAN termination point. It is installed in the building as part of the prewiring, and the itnernal lines are connected to it