Chapter 2 Flashcards
What is the basic purpose of a network?
to make connections
What is the term given to a network transporting multiple types of traffic?
converged network
Networks are defined by
Geography
Topology
Resource location
Based on the geographic dispersion of network components, you can classify network into various categories, including …. (list in book)
Local area network (LAN)
Wide area network (WAN)
Campus area network (CAN)
Metropolitan area network (MAN)
Personal area network (PAN)
Wireless local area network (WLAN)
Storage area network (SAN)
What is a network overlay?
An overlay network is a virtual or logical network that is created on top of an existing physical network.
What is a network underlay?
underlay network is physical infrastructure above which overlay network is built
What does IEEE stand for?
Institute of Electrical and Electronics Engineers
which is an internationally recognized standards body
Describe a LAN (local area network)
A LAN interconnects network components within a local area
What are some examples of common LAN technologies?
Ethernet and wireless networks
IEEE for ethernet
802.3
IEEE for wireless networks
802.11
What is the distance limitation of a LAN?
Usually 100 meters or less
a room or a building
Describe a WAN (wide area network)
A WAN interconnects network components that are geographically separated.
What are some example of WAN technologies?
Multiprotocol Label Switching (MPLS) and Asynchronous Transfer Mode (ATM)
Why might a WAN be used?
a corporate headquarters might have multiple WAN connections to remote office sites
What is the scale of a WAN?
state, country, global
a few miles to thousands of miles
Describe a SAN (storage area network)
high-speed, highly reliable network for the express purpose of transmitting stored data
Which two geographical categories are the most common?
WAN and LAN
Describe a CAN (campus area network)
Individual LANs that were also interconnected
The interconnection of LANs creates a campus area network
CAN (beside campuses) can be used in industrial parks and business parks
What is the scale of a CAN?
Cluster of buildings
Usually a mile or less
Describe a MAN (metropolitan area network)
A CAN is more widespread than a CAN but less than a WAN
A MAN interconnects locations scattered throughout a metropolitan area.
What is the scale of a MAN?
city
usually a few miles or less
Describe a PAN ( personal area network)
A PAN is a network whose scale is even smaller than a LAN
For example, a connection between Bluetooth headphones and a cell phone.
What is the scale of a PAN?
Human
a few meters
What is a software-defined wide area network (SD-WAN)
provides a simple policy and profiles approach to managing the WAN
it also provides tool that enable new levels of visibility into and control over the use of the varied WAN circuits in the typical enterprise today
Why is a Multiprotocol Label Switching (MPLS) growing in popularity as a WAN technology?
due to MPLS’s capability to support multiple protocols on the same network
Give a description of a client/server network
a collection of PCs all sharing files stored on a centralized server
Give a description of a peer-to-peer network
PCs operating system configured for file sharing, they could share files from one another’s hard drives
peers make resources available to other peers
Client/server networks are commonly used by
business
Is administration simpler on client/server or peer-to-peer networks?
client/server because resources are found on one or more servers, administration is simpler than administration of network resources on multiple peer devices.
The performance of a client/server network can be better than that of a peer-to-peer network because
resources can be located on dedicated servers rather than on a PC running a variety of end-user applications.
Can backup be done easier on client/server or peer-to-peer?
client/server because you can simplify backups because fewer locations must be backed up.
Client/Server – Client devices share a common set of resources located on one or more dedicated server. What would be the benefit of this and what is the drawback?
Benefit -> Can scale easily -might require the purchase of additional client licenses
Drawback -> Because multiple clients might rely on a single server for their resources, the single server can become a single point of failure in the network.
Administration is simplifies in client/server because…
parameters such as file-sharing permissions and other security settings can be administered on a server as opposed to on multiple clients
Which cost more client/server or peer-to-peer?
Client/server networks can cost more than peer-to-peer networks.
Describe peer-to-peer network
peer-to-peer networks allow interconnected devices to share their resources with one another
Where do peer-to-peer networks tend to be used?
smaller businesses and in homes
As the number of devices increases in a peer-to-peer, the administration burden _______.
increases
Compared to client/server, peer to peer are _____ to be installed. Why?
Easier
because resource sharing is made possible by the clients’ operating systems, and knowledge of advanced networking operating systems is not required
Peer to peer cost less because
there is no requirement for dedicated server resources or advanced NOS software
Why is performance not the best in a peer to peer?
Because devices providing network resources might be performing other tasks not related to resource sharing
A network that has a mixture of client/server and peer to peer characteristics is called what?
hybrid network
The actual traffic flow determines the
logical topology
The way components are physically interconnected determines the
physical topology
What does MAU stand for?
media access unit
Describe the bus topology
typically has a cable running through the area that requires connectivity, and devices that need to connect to network tap into this cable
What connectors does the bus topology use?
T connector (used in older 10BASE2 networks) or a vampire tap (used in older 10BASE5 networks)
A bus and all devices connected to that bus make up a network segment. Why would this be bad?
A single network segment is a single collision domain, which means that all devices connected to the bus might try to gain access to the bus at the same time, resulting in an error condition known as a collision.
One cable is used per network segment in a bus. What are the benefits and drawbacks if there are any?
Benefit -> less cable is needed
Drawback -> Because a single cable is used per network segment, the cable is potentially a single point of failure
Is troubleshooting a bus topology difficult because…
problem isolation might require inspection of multiple network taps to make sure they either have a device connected or are properly terminated
Scaling with a bus topology is difficult because…
adding devices to a bus might cause an outage for other users on the bus
all devices on the bus share bandwidth available
What happens if two devices request access to the bus?
an error condition results
Ring topology
traffic flows in a circular fashion around a closed network loop (that is, a ring)
A ring topology send data how?
in a single direction to each connected device until the intended destination receives the data `
What is counter-rotating rings?
a ring topology made of two rings that send data in opposite directions
What is one benefit of counter-rotating rings?
If a fiber broke, the stations on each side of the break could interconnect their two rings to create a single ring capable of reaching all stations on the ring
If a ring topology had a single ring what would it risk?
a single point failure
Each device on a ring includes both a receiver and a transmitter. What are the benefits and drawbacks of this?
Trouble shooting is simplified in the event of a cable break because each device on a ring contains a repeater.
Rings have scalability limitations. Specifically, a ring has a maximum length and a maximum number of attached stations.
Because a ring must be a complete loop, the amount of cable required for a ring is _____ than the amount of cable required for a bus topology serving the same number of devices.
unusually higher
Describe a star topology
hub at the center of the topology and a collection of clients individually connected to the hub
In LANs in the early 1900s, the centralized device was typically a _____. Modern networks, however, usually have a _____ located at the center of the star.
hub
switch
What topology is the most popular physical LAN topology in use today?
star topology
with an Ethernet switch at the center of the star and unshielded twisted-pair (UTP) cable to connect from the switch ports to clients.
In a star topology devices have independent connections to a central device. What are the benefits and drawbacks of this?
A cable break impacts only the device connected via the broken cable and not the entire topology
More cable is required for a star topology than for bus or ring topologies because each device requires its own cable to connect back to the central device.
Is troubleshooting easy or difficult in a star topology?
Troubleshooting is relatively simple because a central device in the star topology acts as the aggregation point for all the connected devices.
Describe a hub and spoke
a WAN link from each remote site (that is, a spoke site) to the main site (that is, the hub site)
How do two spoke locations communicate?
If two spoke locations need to communicate with each other, their communication is sent via the hub location.
In a hub and spoke, each remote site (spoke) connects to a main site (hub) via a WAN link. What is the benefit and drawback to this?
Benefit -> Cost are reduced because a minimal number of links is used
Drawback -> Suboptimal routes must be used between remote sites because all inter-site communication must travel via the main site (hub).
Because all remote sites converge on the main site, the hub site is potentially a ….
single point failure
Describe a full mesh topology
a full mesh topology directly connects every site to every other site
Because a full mesh topology connects every site to every other site, a ______ path can be selected.
optimal
What is the equation for figuring out how many connections a full mesh topology has?
2
A full mesh network can be difficult and expensive to scale because …
the addition of one new site requires a new WAN link between the new site and every other existing site.
A full mesh is fault tolerant because …
one or more links can be lost, and reachability between all sites might still be maintained
Troubleshooting a full-mesh network is …
relatively easy because each link is independent of the other links
describe a partial-mesh topology
a partial-mesh WAN topology is a hybrid of the hub and spoke and full mesh topology
can be designed to offer an optimal route between selected sites while avoiding the expense of interconnecting every site to every other site
A partial-mesh topology is ____ fault tolerant than a full mesh topology
less
A partial-mesh is more expensive than ________ but less expensive than _____.
hub and spoke
full mesh
What is a demarcation point?
the point in a telephone network where the maintenance responsibility passes from a telephone company to the subscriber
Where is the demarc typically located?
in a box mounted to the outside of a customer’s building
the box is called a network interface device (NID)
What is a smartjack?
a type of network interface device that adds circuitry
This circuity adds such features as converting between framing formats on a digital circuit, supporting remote diagnostics, and regenerating a digital signal.
What is a hypervisor and what does it do?
Virtualization is possible with servers thanks to specialized software called a hypervisor.
The hypervisor takes physical hardware and abstracts it for the virtual server.
What does NIC stand for?
network interface card
What does NAS stand for?
Network attached storage
What does iSCSI stand for and what is it?
internet Small Computer System Interface
A technology for network storage
IP-based
A client using iSCSI is called?
an initiator
The system providing the iSCSI is called?
iSCSI target
What are larger than normal frame sizes called?
Jumbo frames
What does FCoE stand for?
Fiber Channel over Ethernet
What is IB and what does it do?
InfiniBand
permits high speed, low-latency , communications between supercomputers
What is NFV? What does it do?
Neatwork function virtualization
is the replacement of network appliance hardware with virtual machines
NFV can include security, storage, compute, and monitoring services
To avoid Quality of Service and security implication, what is used?
vSwitch
it allows for the Layer 2 control in a virtual server
Describe why a satellite provider link would be used?
rural locations lack the option of connecting to an IP WAN or to the internet via physical media
Most satellites used for WAN connectivity are in orbit above the earth’s equator. About how high are they?
22,300 miles high
What are the two design considerations that need to be taken into account?
Delay and sensitivity to weather conditions
What is the speed of the radio waves?
radio waves travel at the speed of light
186,000 miles per sec
3*10^8 meters per sec
Why do weather conditions affect satellite connections?
Because communication between a customer’s satellite dish and an orbiting satellite must travel through the earth’s atmosphere, weather conditions can impede communications.
What does DSL stand for?
digital subscriber line (DSL)
Describe a DSL
DSL is a group of technologies that provide high-speed data transmission over existing telephone wiring
What does ADSL stand for?
Asymmetric DSL (digital subscriber line)
What does ADSL do?
ADSL allows an existing analog telephone to share the same line used for data for simultaneous transmission of voice and data.
What is the distance limitation of ADSL?
18000 feet
The term asymmetric in asymmetric DSL indicates what?
that the upstream and downstream speeds can be different
typically downstream speeds are greater than upstream speeds in an ADSL connection
What is the speed for an ADSL downstream connection and a upstream connection.
down - 8Mbps
up - 1.544Mbps
What does SDSL stand for?
symmetric digital subscriber line
What is the difference between ADSL and SDSL?
Where ADSL has unequal speeds, SDSL has equal speeds
SDSL does not allow simultaneous voice and data on the same phone line
What is the speed of SDSL?
1.168 Mbps
What is the maximum distance of SDSL?
12,000 feet between a DSL modem and its DSLAM
What does VDSL stan for?
very high bit-rate DSL
What are the downstream and upstream speeds of VDSL?
down-52 Mbps
up - 12 Mbps
What is the distance limitation of VDSL?
4000 feet of telephone cable between a cable modem and a DSLAM
What is a hybrid fiber-coax distribution network (HFC)?
An infrastructure containing both coaxial and fiber-optic cabling
Why would an infrastructure have a HFC (hybrid fiber-coax) distribution network?
These networks can designate specific frequency ranges for upstream data transmission
The device located in a residence (or a business) that can receive and transmit in specific frequencies ranges is known as what?
cable modem
What are the typically given ranges for upstream and downstream data in a cable modem?
up - 5 MHz to 42 MHz
down - 50 MHz to 860 MHz
Although the theoretical max upstream/downstream bandwidth limits are greater, most upstream speeds are limited to ____, with downstream speeds limited to around _____. (cable modems)
20Mbps
200Mbps
The current theoretical maximums are ____ upstream and ____ downstream. (cable modems)
1 Gbps
10 Gbps
The frequencies dedicated to data transmission are specified by a …
Data over cable service interface specification version
What is a leased line
typically a point-to-point connection interconnecting two sites
What is the difference between a leased line and a packet-switched connection?
The bandwidth of a dedicated leased line connection does not need to be shared among multiple service provider customers.
WAN technologies used with dedicated leased lines include digital circuits. list them
T1
E1
T3
E3
The circuits (T1,E1,T3,E3) can use _______ technology to simultaneously carry multiple conversations in different 64Kbps channels.
multiplexing
A single 64Kbps channel is called what?
Digital Signal 0 (DS0)
What does CSU/DSU stand for?
channel service unit/ data service unit
What does a CSU/DSU?
a channel service unit/data service unit converts a digital data frame from local area network (LAN) communication technology into a frame appropriate for a wide area network (WAN) and vice versa.
A common Layer 2 protocol used on dedicated leased lines is …
Point-to-Point Protocol (PPP)
A common connection type used to connect to a CSD/DSU is
an RJ-48C
RJ-45
ethernet connector
What is another protocol used on dedicated leased lines that is less common than PPP?
`High level Data Link Control (HDLC)
T1 circuit were originally used where?
telephony networks, with the intent of voice conversation being carried in a single channel
A T1 circuit is composed of ….
24 DS0s which is called a Digital Signal 1 (DS1)
What is the bandwidth of a T1 circuit?
1.544 Mbps
In a T1 environment, more than one frame is sent at once. What are the two approaches to grouping these frames?
Super Frame (SF) - combines 12 standard 193 bit frames into a super frame
Extended Super Frame (ESF) - Combines 24 standard 193 bit frames into an extended super frame
Where are T1s popular?
North America and Japan
An E1 circuit contains 32 channels; however, only 30 of those channels can transmit data. What do those two channels do and which ones are they?
Channel 1 is reserved for framing and synchronization
Channel 17 is reserved for signaling (setting up, maintaining, and tearing down a call)
E1 has higher bandwidth capacity than T1. What is the bandwidth capacity of E1?
2.048 Mbps
Unlike a T1 circuit, an E1 does not group frames in an SF or an ESF. The E1 circuit groups …
16 frames in a multiframe
T3 circuit is in the same T carrier family of standards as T1, but T3 offers an increased bandwidth capacity. What is the bandwidth capacity of T3
44.7 Mbps
T3 combines ____ DS0s into a single physical connection, delivered to the customer over _______ cable, which is called _____.
672 DS0s
coaxial cable
Digital Signal 3 (DS3)
Just as a T3 circuit provides more bandwidth than a T1 circuit, and E3 circuit’s available bandwidth is greater than an E1. What is the E3 bandwidth?
34.4 Mbps
Which circuit provides the most bandwidth?
T1,E1,T3,E3
T3
Telecommunication networks today are often divided into a three-tier hierarchy, consisting of
the access section
the metropolitan section
the long-haul section
Metropolitan section plays an important role what is it?
it connect both the access section and the long-haul section
The metropolitan section typically covers an area of 10 to 100 km and is often based on a ______ ring architecture.
SONET
What does SONET stand for?
synchronous optical network
SONET is a layer _____ technology and uses ____ as its media
layer 1
fiber-optic cabling
What is the data range and distance limitations of SONET?
155Mbps - 10Gbps
20km to 250km
