Lesson 1 Flashcards
1
Q
Is a worldwide system of computer networks
A
Internet
2
Q
A network of networks
A
Internet
3
Q
Hosts = ___________
A
End Systems
4
Q
Communication Links
A
Fiber, copper, radio, satellite
5
Q
Transmission rate of Communication Links
A
Bandwidth
6
Q
a measurement indicating the maximum capacity of a wired or wireless communications link to transmit data over a network connection in a given amount of time.
A
Network bandwidth
7
Q
is used to forward packets (chunks of data)
A
Packet Switches
8
Q
Hardware in Packet Switching
A
Routers and Switches
9
Q
connects multiple devices to create a network
A
Switch
10
Q
connects multiple switches, and their respective networks, to form an even larger network.
A
Router
11
Q
- IP picture frame
- Web enabled toaster
- Internet refrigerator
- Sensorized bed mattress
- Internet Phones
- Tweet-a-watt monitor energy use
A
Examples of “Fun” Internet-connected devices
12
Q
Internet
A
” network of networks “
13
Q
Interconnected ISPs
A
Internet
14
Q
control sending, receiving of messages
A
Protocols
15
Q
Example of Protocols
A
- TCP
- IP
- HTTP
- Skype
- 802.11
16
Q
Example of Internet Standards
A
- RFC
- IETF
17
Q
Services that the Internet provides
A
- Infrastructure that provides services to applications
- Provides programming interface to apps
18
Q
Web
VoIP
Email
Games
E-commerce
Social nets
A
Infrastructure that provides services to applications
19
Q
Hooks that allow sending and receiving app programs to “connect” to internet and Provides service options, analogous to postal service
A
Provides programming interface to apps
20
Q
are defined format, of message sent and received among network entities, and actions taken on message transmission, receipt
A
Protocols
21
Q
exchanging messages and taking actions in human
A
Human Protocol
22
Q
the entities exchanging messages and taking actions are hardware or software components of a computer network
A
Network Protocols
23
Q
All communication activity in Internet governed by _____________.
A
protocols
24
Q
Example of Human Protocol
A
Greetings like “Hi” and “ Hello”
25
Network Structure
1. Network Edge
2. Access networks, Physical Media
3. Network Core
26
Network Edge
Hosts: Clients and servers often in data centers
27
Access networks, Physical Media:
Wired, and wireless communication links
28
How to connect end systems to edge routers?
1. Residential access nets
2. Institutional access networks (School and company)
3. Mobile access networks
29
Bandwidth unit measurement
BPS/ Bits per second
30
refers to internet connection where you have exclusive access to the connection infrastructure
Dedicated Network
31
Means your internet connection uses the same infrastructure as your neighbors
Shared Network
32
Digital Subscriber Line (DSL)
is a type of network connection that uses existing telephone line to central office DSLAM
33
Data over DSL phone line goes to ________
Internet
34
Where does the Voice over DSL phone line go?
telephone net
35
Frequency division multiplexing
The different channels are transmitted in different frequency bands
36
Asymmetric: up to 30 Mbps downstream transmission rate, 2 Mbps upstream transmission rate
HFC: Hybrid Fiber Coax
37
The network of cable, fiber attaches homes to ISP router
HFC
38
Does DSL has dedicated access to central office?
Yes
39
Wireless Devices -> Wireless Access Point -> Router, Firewall, NAT -> Wired Ethernet Connected to router -> Cable or DSL Modem -> Central Office
Home Network Connections
40
ENTERPRISE ACCESS NETWORKS (ETHERNET)
- Typically used in companies, universities, etc.
- 10 Mbps, 100 Mbps, 1 Gbps, 10 Gbps transmission rates
- Today, end systems typically connected into Ethernet Switch
41
EXAMPLES OF WIRELESS ACCESS NETWORKS
1. Wireless LANs
2. Wide-area wireless access
42
- Within a building (100 ft.)
- 801.1 1b/g/n (WiFi): 11,54,450 Mbps transmission rate
Wireless LANs
43
- Provided by telco (cellular)
- Between 1 and 10 Mbps
- 3G, 4G: LTE
Wide-area wireless access
44
Shared wireless access network connects end systems to router
WIRELESS ACCESS NETWORKS
45
1. Takes application message
2. Breaks into smaller chunks, known as packets, of Length L bits
3. Transmits packet into access network at transmission rate R
Host sending function
46
Physical Media: Propagates between transmitter/receiver pairs
Bit
47
Physical Media: What lies between transmitter & receiver
Physical Link
48
Physical Media: Signals propagate in solid media: copper, fiber, coax
Guided Media
49
Physical Media: Signals propagate freely
e.g., radio
Unguided Media
50
Physical Media: Two insulated copper wires
Twisted Pair (TP)
51
2 Twisted Pair cable categories
1. Category 5
2. Category 6
52
TP Category: 100 Mbps, 1 Gbps Ethernet
Category 5
53
TP Category: 10 Gbps
Category 6
54
Physical Media: Types of Cable
1. Coax cable
2. Fiber optic cable
55
- Two concentric copper conductors
- Bidirectional
- broadband:
Coax cable
56
- Glass fiber carrying light pulses, each pulse a bit
- High-speed operation
- Low error rate
Fiber optic cable
57
- Signal carried in electromagnetic spectrum
- No physical “wire”
- Bidirectional
Radio
58
Propagation environment effects of Radio Transmission
1. Reflection
2. Obstruction by objects
3. Interference
59
Mesh Interconnected routers
Network Core
59
RADIO LINK TYPES:
1. Terrestrial Microwave
2. LAN
3. Wide-area
4. Satellite
60
Packet-switching
hosts break application-layer messages into packets
61
PACKET-SWITCHING: STORE-AND-FORWARD
entire packet must arrive at router before it can be transmitted on next link
62
PACKET-SWITCHING: QUEUEING DELAY AND LOSS
Packets will queue, wait to be transmitted on link. Packets can be dropped (lost) if memory (buffer) fills up
63
TWO KEY NETWORK-CORE FUNCTIONS
1. Routing
2. Forwarding
64
Determines source-destination route taken by packets
ROUTING
65
Moves packets from router’s input to appropriate router output
FORWARDING
66
End-end resources allocated to reserved for “call” between source & dest
CIRCUIT SWITCHING
67
Allows more users to use network
Packet-Switching
68
it works with digital signals as well as analog signals
Time division multiplexing (TDM)
69
It works with only analog signals.
(FDM) Frequency division multiplexing
70
How many users can accommodate in Circuit Switching?
10 Users
71
How many users can accommodate in Packet Switching?
With 35 users, probability > 10 active at same time
72
Private network that connects its data centers to internet, often by passing tier-1, regional ISPs
Content Provider Network
73
(Packets queue in router buffers)
- Packet arrival rate to link (temporarily) exceed output link capacity
- Packets queue, wait for turn
HOW DO LOSS AND DELAY OCCUR
74
FOUR SOURCES OF PACKET DELAY
1. Nodal processing
2. Queueing delay
3. Transmission delay
4. Propagation delay
75
Source of Packet Delay:
1.Check bit errors
2. Determine output link
3. Typically
Nodal Processing
76
Source of Packet Delay:
1. Time waiting at output link for transmission
2. Depends on congestion level of router
QUEUEING DELAY
77
Source of Packet Delay:
1. L: packet length (bits)
2. R: link bandwidth (bps)
Transmission Delay
78
Source of Packet Delay:
1. d: length of physical link
2. S: propagation speed ( ~ 2x 10 ^8 m/sec
Propagation Delay
79
It provides delay measurement from source to router along the end-end Internet path towards destination.
TRACEROUTE PROGRAM
80
Queue or also known as buffer, is a preceding link in a buffer that has finite capacity.
Packet Loss
81
Packet arriving to full queue dropped or also known as __________
Loss
82
Lost packet may be retransmitted by previous node, by source end system, or not at all
Packet Loss
83
Throughput
Bits are transferred between sender or receiver
84
Throughput: rate at a given point in time
Instantaneous
85
Throughput: is a rate over long period of time
Average
86
Bottleneck Link
link on end-end path that constrains end-end throughput
87
Networks are complex with many __________
Pieces
88
1. Hosts
2. Routers
3. Links of various media
4. Applications
5. Protocols
6. Hardware, software
" Pieces " of Networks
89
each ________ implements a service
layer
90
Layering
it helps to deal with complex systems
91
INTERNET PROTOCOL STACK
1. Application
2. Transport
3. Network
4. Link
5. Physical
92
Protocol Stack: Application
Supporting network applications
93
Protocol Stack: Transport
process -process data transfer
94
Protocol Stack: Network
Routing of datagrams from source to destination
95
Protocol Stack: Link
Data transfer between neighboring network elements
96
Protocol Stack: Physical
Bits “on the wire”
97
FTP, SMTP, HTTP
Example of supporting network applications
98
TCP, UDP
Examples of Process-process data transfer
99
ISO/ OSI REFERENCE MODEL
1. Application
2. Presentation
3. Session
4. Transport
5. Network
6. Link
7. physical
100
Allow applications to interpret meaning of data
- e.g., encryption
- Compression
- Machine-specific conventions
Presentation
101
Synchronization, checkpointing, recovery of data exchange
Session
102
SOURCE ( Flow )
Message -> Segment -> datagram ->
frame
103
the protection of the underlying networking infrastructure from unauthorized access, misuse, or theft
NETWORK SECURITY
104
Enumerate what Bad Guys can do
1. PUT MALWARE INTO HOSTS VIA INTERNET
2. ATTACK SERVER, NETWORK INFRASTRUCTURE
3. CAN SNIFF PACKETS
4. CAN USE FAKE ADDRESSES
105
Malware can get in host form:
1. Virus
2. Worm
106
Self-replicating infection by receiving or executing object
Virus
107
Example of Virus
Email Attachment
108
Self-replicating infection by passively receiving object that gets itself executed
Worm
108
Can record keystrokes, websites visited, and upload information to collection site
Spyware malware
109
Infected host can be enrolled in ______, used for spam.
botnet
110
Attackers make resources (server, bandwidth) unavailable to legitimate traffic by overwhelming resource with bogus traffic
Denial of Service (DoS)
111
1. Select target
2. Break into host around the network (see botnet)
3. Send packets to target from compromised hosts
Process of DoS
112
a method of detecting and assessing packet data sent over a network.
Packet Sniffing
113
- Broadcast media
- Promiscuous network interface reads/records all packets passing by
Packet " Sniffing "
114
Send packet with false source address
IP Spoofing
115
Types of Defense in Network Security
1. Access control. This method limits access to 2. network applications and systems to a specific group of users and devices. ...
3. Antivirus and antimalware. ...
4. Application security. ...
5. Behavioral analytics. ...
6. Cloud security. ...
7. Data loss prevention (DLP). ...
8. Email security. ...
9. Firewall.
