Chapter 5-Networking
True or false? Connecting two or more internetworking devices by a single cable in a daisy-chain fashion makes the serial network backbone complex.
false
5-4-3 rule
guideline for 10Mbps Ethernet networks stating that between two communicating nodes, the network cannot contain more than five network segments connected by four repeating devices, and no more than three of the segments may be populated.
The term ____ refers to the way in which data is transmitted between nodes.
logical topology
MPLS stands for
multiprotocol label switching
PSE stands for
power sourcing equipment
PD stands for
powered device
SFD stands for
start-of-frame delimiter
A physical ____ is the physical layout, or pattern, of the nodes on a network.
topology
True or false? On heavily trafficked Ethernet network segments, collisions are fairly common.
true
True or false? The most common logical topologies are bus and ring.
true
True or false? The most popular method for connecting nodes on a network is packet switching.
true
True or false? The various Ethernet standards for copper cable utilize encoding methods that affect maximum throughput, segment length, and wiring requirements.
true
CSMA/CD stands for
carrier sense multiple access with collision detection
collision
In Ethernet networks, the interference of one node's data transmission with the data transmission of another node sharing the same segment.
broadcast domain
Logically grouped network nodes that can communicate directly via broadcast transmissions. For example, all nodes connected to a single hub and all nodes that participate in a bus-topology network belong to a single broadcast domain.
padding
The bytes added to the data (or information) portion of an Ethernet frame to ensure this field is at least 46 bytes in size. Padding has no effect on the data carried by the frame.
fault tolerance
The capability for a component or system to continue functioning despite damage or malfunction.
preamble
The field in an Ethernet frame that signals to the receiving node that data is incoming and indicates when the data flow is about to begin.
data propagation delay
The length of time data takes to travel from one point on the segment to another point. On Ethernet networks, CSMA/CD's collision detection routine cannot operate accurately if the data propagation delay is too long.
Ethernet_II
The original Ethernet frame type developed by Digital, Intel, and Xerox, before the IEEE began to standardize Ethernet. Ethernet_II contains a 2-byte type field to identify the upper-layer protocol contained in the frame. It supports TCP/IP and other higher-layer protocols.
physical topology
The physical layout of a network. A physical topology depicts a network in broad scope; it does not specify devices, connectivity methods, or addresses on the network. Physical topologies are categorized into three fundamental geometric shapes: bus, ring, and star. These shapes can be mixed to create hybrid topologies.
collision domain
The portion of an Ethernet network in which collisions can occur if two nodes transmit data at the same time.
QoS
The result of specifications for guaranteeing data delivery within a certain period of time after their transmission.
bus
The single cable connecting all devices in a bus topology.
What switching technique establishes a connection between two network nodes before transmitting data?
a
Which of the following is a 10-Gigabyte Fiber-optic Ethernet standard?
a
terminator
A resistor that is attached to each end of a bus-topology network and that causes the signal to stop rather than reflect back toward its source.
bus topology
A topology in which a single cable connects all nodes on a network without intervening connectivity devices.
active topology
A topology in which each workstation participates in transmitting data over the network. A ring topology is considered an active topology.
100Base-TX
A type of 100Base-T network that uses two wire pairs in a twisted pair cable but uses faster signaling to achieve 100Mbps throughput. It is capable of full-duplex transmission and requires Cat 5 or higher twisted pair media.
Gigabit Ethernet
A type of Ethernet network that is capable of 1000Mbps, or 1Gbps, throughput.
Fast Ethernet
A type of Ethernet network that is capable of 100Mbps throughput. 100Base-T and 100Base-FX are both examples of Fast Ethernet.
distributed backbone
A type of backbone in which a number of connectivity devices (usually hubs) are connected to a series of central connectivity devices, such as hubs, switches, or routers, in a hierarchy.
parallel backbone
A type of backbone that consists of more than one connection from the central router or switch to each network segment.
serial backbone
A type of backbone that consists of two or more internetworking devices connected to each other by a single cable in a daisy chain. Hubs are often connected in this way to extend a network.
collapsed backbone
A type of backbone that uses a router or switch as the single central connection point for multiple subnetworks.
message switching
A type of switching in which a connection is established between two devices in the connection path; one device transfers data to the second device and then breaks the connection. The information is stored and forwarded from the second device after a connection between that device and a third device on the path is established.
circuit switching
A type of switching in which a connection is established between two network nodes before they begin transmitting data. Bandwidth is dedicated to this connection and remains available until users terminate the communication between the two nodes.
packet switching
A type of switching in which data is broken into packets before it is transported. In packet switching, packets can travel any path on the network to their destination, because each packet contains a destination address and sequencing information
MPLS
A type of switching that enables any one of several Layer 2 protocols to carry multiple types of Layer 3 protocols. One of its benefits is the ability to use packet-switched technologies over traditionally circuit-switched networks. MPLS can also create end-to-end paths that act like circuit-switched connections.
10GBase-EW
A variation of the 10GBase-ER standard that is specially encoded to operate over SONET WAN links.
10GBase-LW
A variation of the 10GBase-LR standard that is specially encoded to operate over SONET WAN links.
10GBase-SW
A variation of the 10GBase-SR standard that is specially encoded to operate over SONET WAN links.
enterprise
An entire organization, including local and remote offices, a mixture of computer systems, and a number of departments. Enterprise-wide computing takes into account the breadth and diversity of a large organization's computer needs.
All Ethernet networks use the ____ access method.
CSMA/CD
Which of the following describes a ring topology?
b
A star-wired bus is referred to as which of the following topology types?
c
Which of the following has a backbone network topology that uses a router or switch as the single central connection point for multiple subnetworks?
c
Most modern networks rely on ____ frames.
Ethernet_II
SFD
A 1-byte field that indicates where the data field begins in an Ethernet frame.
logical topology
A characteristic of network transmission that reflects the way in which data is transmitted between nodes (which may differ from the physical layout of the paths that data takes). The most common logical topologies are bus and ring.
switching
A component of a network's logical topology that manages how packets are filtered and forwarded between nodes on the network.
daisy chain
A group of connectivity devices linked in a serial fashion.
star-wired bus topology
A hybrid topology in which groups of workstations are connected in a star fashion to hubs that are networked via a single bus.
star-wired ring topology
A hybrid topology that uses the physical layout of a star and the token-passing data transmission method.
modal bandwidth
A measure of the highest frequency of signal a multimode fiber-optic cable can support over a specific distance. Modal bandwidth is measured in MHz-km.
PoE (Power over Ethernet)
A method of delivering current to devices using Ethernet connection cables.
CSMA/CD
A network access method specified for use by IEEE 802.3 (Ethernet) networks. In CSMA/CD, each node waits its turn before transmitting data to avoid interfering with other nodes' transmissions. If a node's NIC determines that its data has been involved in a collision, it immediately stops transmitting. Next, in a process called jamming, the NIC issues a special 32-bit sequence that indicates to the rest of the network nodes that its previous transmission was faulty and that those data frames are invalid. After waiting, the NIC determines if the line is again available; if it is available, the NIC retransmits its data.
ring topology
A network layout in which each node is connected to the two nearest nodes so that the entire network forms a circle. Data is transmitted unidirectionally around the ring. Each workstation accepts and responds to packets addressed to it and then forwards the other packets to the next workstation in the ring.
passive topology
A network topology in which each node passively listens for, and then accepts, data directed to it. A bus topology is considered a passive topology.
access method
A network's method of controlling how nodes access the communications channel. For example, CSMA/CD (Carrier Sense Multiple Access with Collision Detection) is the access method specified in the IEEE 802.3 (Ethernet) standard.
jamming
A part of CSMA/CD in which, upon detecting a collision, a station issues a special 32-bit sequence to indicate to all nodes on an Ethernet segment that its previously transmitted frame has suffered a collision and should be considered faulty.
signal bounce
A phenomenon, caused by improper termination on a bus-topology network, in which signals travel endlessly between the two ends of the network, preventing new signals from getting through.
10GBase-SR
A physical layer standard for achieving 10Gbps data transmission over multimode fiber using wavelengths of 850 nanometers. The maximum segment length for 10GBase-SR can reach up to 300 meters, depending on the fiber core diameter and modal bandwidth used.
10GBase-LR
A physical layer standard for achieving 10Gbps data transmission over single-mode, fiber-optic cable using wavelengths of 1,310 nanometers. In 10GBase-LR, the LR stands for long reach. This standard specifies a star topology and segment lengths up to 10 kilometers.
10GBase-ER
A physical layer standard for achieving 10Gbps data transmission over single-mode, fiber-optic cable. In 10GBase-ER, the ER stands for extended reach. This standard specifies a star topology and segment lengths up to 40 kilometers.
10GBase-T
A physical layer standard for achieving 10Gbps data transmission over twisted pair cable. Described in its 2006 standard 802.3an, IEEE specifies Cat 6 or Cat 7 cable as the appropriate medium for 10GBase-T. The maximum segment length for 10GBase-T is 100 meters.
100Base-FX
A physical layer standard for networks that specifies baseband transmission, multimode fiber cabling, and 100Mbps throughput. 100Base-FX networks have a maximum segment length of 2,000 meters. 100Base-FX may also be called Fast Ethernet.
100Base-T
A physical layer standard for networks that specifies baseband transmission, twisted pair cabling, and 100Mbps throughput. 100Base-T networks have a maximum segment length of 100 meters and use the star topology. 100Base-T is also known as Fast Ethernet.
10Base-T
A physical layer standard for networks that specifies baseband transmission, twisted pair media, and 10Mbps throughput. 10Base-T networks have a maximum segment length of 100 meters and rely on a star topology.
star topology
A physical topology in which every node on the network is connected through a central device, such as a hub. Any single physical wire on a star network connects only two devices, so a cabling problem will affect only two nodes. Nodes transmit data to the hub, which then retransmits the data to the rest of the network segment where the destination node can pick it up.
hybrid topology
A physical topology that combines characteristics of more than one simple physical topology.
PD
On a network using Power over Ethernet, a node that receives power from power sourcing equipment.
PSE
On a network using Power over Ethernet, the device that supplies power to end nodes.
The IEEE 802.3af standard, which specifies a method for supplying electrical power over Ethernet connections, is also known as ____.
PoE
QoS stands for
Quality of service