INSY3303: Network Architecture and Design (Ch. 6-9)
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1
What are the seven network architecture components?
LAN, building backbone, campus backbone, data center, WAN, Internet access, e-commerce edge
2
Which architecture component is also called the access layer?
LAN
3
Which architecture component is also called the distribution layer?
Building backbone
4
Which architecture component is also called the core layer?
Campus backbone
5
Which three components make up the enterprise edge?
WAN, Internet access, e-commerce edge
6
What is the e-commerce edge?
A special LAN for electronic data exchange with outside business partners
7
What is the traditional network design process called?
Structured systems analysis and design (waterfall)
8
Why is the traditional design process less appropriate today?
Technology changes rapidly, traffic growth is immense, and the balance of costs has changed
9
What is the building-block design process also called?
Narrow and deep
10
What is the goal of building-block design?
Simplicity, by reusing a few standard components
11
What are the three steps of building-block design?
Needs analysis, technology design, cost assessment
12
Is the building-block process linear or cyclical?
Cyclical
13
What does needs analysis determine?
Why the network is built and which users and applications it supports
14
What does needs analysis produce?
A logical network design (no technologies or products specified)
15
What is baselining?
Reviewing the applications that use the network and where each is located
16
Into what three categories are requirements sorted?
Mandatory, desirable, wish-list
17
What is the deliverable of needs analysis?
Logical network diagrams
18
What does technology design produce?
Physical network designs
19
What is capacity planning?
Deciding the capacity of each circuit
20
What is the turnpike effect?
Traffic grows much faster than forecast because improving the network increases usage
21
What is a bottleneck?
A circuit filled almost to capacity that determines response times
22
Where is the bottleneck in most enterprise networks?
- WAN and Internet
- Data center
- LAN
23
What do network design simulation tools estimate?
Response times and throughput
24
What is CapEx?
Up-front costs such as devices, hardware, circuits, and initial software
25
What is OpEx?
Ongoing costs such as licenses, management, testing, maintenance, and leased WAN/Internet circuits
26
What does a request for proposal (RFP) do?
Specifies desired equipment, software, and services and asks vendors for best prices
27
What are the deliverables of cost assessment?
RFP, revised physical network diagram, business case
28
How does management view the network?
As a cost center
29
Where is network security tightest?
- Core layer and data center
- LAN
- Enterprise edge
30
What does a NIC do in a wireless network?
Acts as a radio transmitter on a specific frequency
31
Which cable type is most common in LANs?
UTP
32
When is STP used?
Only where electrical interference exists
33
Why does a switch act as a repeater?
Signals attenuate over distance
34
What does a wireless access point (AP) do?
A radio transceiver that plays the role of a hub or switch in a WLAN
35
What is the ideal WLAN range?
100–150 meters
36
Why is each AP set to a different channel?
So APs do not interfere with each other
37
Which Wi-Fi band has the longest range and best wall penetration?
- 2.4 GHz
- 5 GHz
- 6 GHz
38
Which Wi-Fi band has the least interference and no legacy devices?
- 6 GHz
- 2.4 GHz
- 5 GHz
39
What is a network operating system (NOS)?
Software that controls the network, with a server version and a client version
40
What layers does the NOS server version cover?
Data link, network, and application layer functions
41
What layers does the NOS client version cover?
Data link and network layers
42
What are the main NOS functions?
Resource sharing, user management, security, communication support
43
What is a directory service?
Information about available network resources (for example, Active Directory)
44
What is a domain?
A logical grouping of network resources in a tree, resolved by a domain controller
45
What is a forest?
Domain trees from different organizations linked together
46
What is a network profile?
Which resources on each server are available and who may access them
47
What IEEE standard is wired Ethernet?
802.3
48
At which layer does Ethernet operate?
Layer 2 (data link), plus layer 1 hardware
49
What is a logical topology?
How the network works conceptually
50
What is a physical topology?
How the network is installed
51
What topology does switch-based Ethernet use?
Logical star and physical star
52
What does a layer 2 switch use to forward frames?
A forwarding table
53
What does a switch do if the destination is not in its forwarding table?
Sends the frame to all ports
54
Which switching mode forwards as soon as it reads the destination address?
- Cut-through
- Store-and-forward
- Fragment-free
55
Which switching mode checks the entire frame before forwarding?
- Store-and-forward
- Cut-through
- Fragment-free
56
Which switching mode checks the first 64 bytes?
- Fragment-free
- Cut-through
- Store-and-forward
57
What media access method does wired Ethernet use?
CSMA/CD (collision detection)
58
What does a NIC send when it detects a collision?
A jamming signal
59
What is the maximum data rate of 100Base-T?
100 Mbps
60
What is the maximum data rate of 1000Base-T?
1 Gbps
61
What IEEE standard is Wi-Fi?
802.11
62
What topology does Wi-Fi use?
Physical star, logical bus
63
What media access method does Wi-Fi use?
CSMA/CA (collision avoidance)
64
What is association in Wi-Fi?
A computer joining a specific AP before communicating
65
What is active scanning?
The NIC sends a probe frame on all active channels
66
What is passive scanning?
The NIC listens on all channels for a beacon frame from an AP
67
What is DCF also called?
Physical carrier sense method
68
How does DCF send frames?
Stop-and-wait ARQ, waiting for an ACK before sending the next frame
69
What is PCF also called?
Virtual carrier sense method
70
What problem does PCF solve?
The hidden node problem
71
How does PCF control access?
Computer sends RTS and the AP replies CTS with a time reservation
72
When does PCF perform better?
In high-traffic WLANs
73
Which standard is Wi-Fi 6?
802.11ax
74
Which standard is Wi-Fi 7?
802.11be
75
What is the speed of 802.11ax?
9.6 Gbps
76
What is a weakness of WEP?
Serious security weaknesses; a determined hacker can break it
77
How does WPA improve on WEP?
A longer key that changes for every frame
78
Which standard is WPA2?
802.11i
79
What does 802.11i use for encryption?
AES
80
How does 802.11i get a master key?
The user logs into a login server
81
Does MAC address filtering stop a determined hacker?
No
82
What is the largest cost in a wired LAN?
Paying someone to install cable
83
When is cabling cheapest to install?
During construction
84
What is the best-practice LAN design?
Wired switched Ethernet for desktops plus a Wi-Fi overlay
85
What should a WLAN design begin with?
A site survey
86
What is the typical design radius for an omnidirectional AP?
About 50 feet
87
What does a Wi-Fi controller do?
Manages APs, reports on devices and load, and can send a laptop to another AP
88
What is a guest network?
A separate, less secure network with its own password for temporary guests
89
What does a load balancer do?
Forwards each request to one server and avoids crashed servers
90
What is server virtualization?
Several logically separate servers running on one physical computer
91
How is virtualization provided?
Natively by some operating systems, otherwise by special-purpose software
92
What is a SAN?
A LAN devoted solely to data storage
93
What is a NAS device?
A small processor with lots of disk that only answers file requests
94
What are the three ways to improve LAN performance?
Increase server performance, increase circuit capacity, reduce network demand
95
How can you add circuit capacity to a wired LAN?
Segment the network by adding switches
96
How can you add circuit capacity to a WLAN?
Add APs on different channels
97
What are the three basic backbone (BN) types?
Switched, routed, VLAN
98
What are the basic BN components?
Cables, classic switches, VLAN switches, routers
99
What topology does a switched BN use?
Star with one switch at the center
100
Which layer commonly uses a switched BN?
Distribution layer
101
What is the MDF or CDF?
The main (or central) distribution facility room holding BN devices
102
What is a chassis switch?
A metal shell with a high-speed backplane holding plug-in modules
103
What is the key advantage of a chassis switch?
Flexibility
104
How does a routed BN move packets?
By network layer address
105
What is a routed BN also called?
Subnetted or hierarchical
106
What does a routed BN do with broadcasts?
Keeps them in one segment
107
What does a VLAN BN do differently?
Assigns computers to LAN segments by software, not hardware
108
What identifies a VLAN?
A VLAN ID number matched to an IP subnet
109
What are VLAN assignments based on?
The physical switch port the computer uses
110
What tagging standard do VLAN switches use between switches?
802.1Q
111
What does the 802.1Q tag contain?
VLAN ID and a priority code
112
What layer does a router operate at?
Layer 3
113
What are the benefits of VLANs?
Same subnet across locations, precise traffic control, traffic prioritization
114
What are the drawbacks of VLANs?
Cost and management complexity
115
What is the best-practice BN for the distribution layer?
Switched or VLAN
116
What is the best-practice BN for the core layer?
Routed
117
What Ethernet speed is the best-practice BN technology?
Gigabit Ethernet
118
How can you increase BN device performance?
Use a better routing protocol (distance vector or link state); add device memory
119
How can you increase BN circuit capacity?
Upgrade to a faster circuit; add circuits
120
How can you reduce BN network demand?
Change user behavior; reduce broadcast messages
121
What does an ACL do on a router?
Specifies what traffic is allowed through, with rules per interface
122
Why are VLANs considered a secure backbone type?
ACLs and other security can be applied at the switch level
123
What is a WAN?
A network connecting offices in different cities or countries using leased circuits
124
Who provides WAN circuits?
Common carriers
125
What are the three WAN service types?
Dedicated circuit, packet switched, VPN
126
What is another name for a dedicated circuit service?
Private line
127
What connection type do dedicated circuits use?
Point to point
128
How are dedicated circuits billed?
Flat monthly fee
129
What is a drawback of dedicated circuits?
More expensive than shared connections
130
What is packet-switched service?
Multiple connections share the same physical circuit and packets are interleaved
131
What are the three packet-switched service types?
Frame relay, MPLS, Ethernet
132
Is frame relay being phased out?
Yes
133
Does frame relay have native encryption or error control?
No
134
What does CIR stand for?
Committed information rate
135
What is CIR?
The rate the PVC guarantees
136
What does MAR stand for?
Maximum allowable rate
137
What is MAR?
The most the network will attempt to provide
138
What does MPLS stand for?
Multiprotocol label switching
139
What does the PE router do in MPLS?
Strips the Ethernet frame and adds an MPLS label
140
What do P routers do in MPLS?
Forward using the label and swap it at each hop
141
What does the CE router do in MPLS?
Delivers the packet to the destination LAN
142
How large is the MPLS header?
32 bits
143
Is the IP header processed along an MPLS path?
No
144
What do Ethernet WAN services avoid?
Translating LAN traffic into a WAN protocol
145
What connection types do Ethernet WAN services support?
Point to point and multipoint
146
What is a VPN?
A private packet-switched network built over the public Internet using PVCs
147
What does a VPN gateway do?
Creates tunnels at each Internet access point
148
What are the advantages of a VPN?
Low cost and flexibility
149
What is the disadvantage of a VPN?
Unpredictable Internet traffic
150
What does an encapsulating VPN do to the packet?
Encapsulates the entire packet
151
What is an intranet VPN?
Virtual circuits between an organization’s own offices over the Internet
152
What is an extranet VPN?
A VPN connecting several different organizations
153
What is an access VPN?
Lets employees access the organization’s network from a remote location
154
What protocol suite encrypts remote-access VPN packets?
IPSec
155
What does ESP stand for?
Encapsulating Security Payload
156
What is SD-WAN?
Software that controls and manages the WAN routers
157
What are the three SD-WAN planes?
Management (orchestration), control, data
158
What is the SD-WAN management plane?
The software used to control the network
159
What is the SD-WAN control plane?
Software that makes decisions
160
What is the SD-WAN data plane?
The routers that implement the network
161
What are the four SD-WAN benefits?
Centralized management, lower costs, more visibility, good security
162
How can you increase WAN device performance?
Upgrade devices; choose a more appropriate routing protocol (static or dynamic)
163
How can you increase WAN circuit capacity?
Analyze traffic and upgrade circuits where needed; check error rates
164
How can you reduce WAN network demand?
Change user behavior; analyze needs of new systems; move data closer to users
165
Why do large organizations use VPNs over WANs?
Encryption is cheap and protects WAN data
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