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CS 335 - Computer Networks > Ch. 1 - Intro to Computer Networks > Flashcards

Ch. 1 - Intro to Computer Networks Flashcards

Internet overview, protocols, networks, performance, layering

1
Q

What is the Internet?

A

Millions of connected computing devices.

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2
Q

Network Protocols

A

Define the format and order of messages sent/received among network entities, and actions taken on message transmission and receipt.

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3
Q

Network structure

A

Network edge, access networks, physical media, and network core

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4
Q

Network Edge

A
  • hosts, access network, physical media
  • Devices connected to the network, such as computers, smartphones, and IoT devices.
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5
Q

Network core

A

mesh of interconnected routers; network of networks

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6
Q

Performance

A

loss, delay, throughput

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7
Q

Key Network Core functions (2)

A
  • forwarding (a.k.a. “switching”)
  • routing
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8
Q

Store-and-Forward

A

entire packet must arrive at router before it can be transmitted on the next link

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9
Q

Packet queueing and loss

A

if arrival rate (in bps) to link exceeds transmission rate (bps) of link for some period of time:
* packets will queue, waiting to be transmitted on output link
* packets can be dropped (lost) if memory (buffer) in router fills up

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10
Q

How are end systems connected to edge routers?

A

Via access networks/nets

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11
Q

DSL

A

Digital Subscriber Line. A method of connecting to the Internet via a phone line. Voice goes over the DSL to the telephone net, and Data goes over to the internet.

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12
Q

Frequency Division Multiplexing

A

different channels transmitted in different frequency bands

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13
Q

Time Division Multiplexing

A

each call allocated periodic slot(s), can transmit at maximum rate of (wider) frequency band (only) during its time slot(s)

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14
Q

What is The difference between DSL and HFC

A

For HFC homes share access network to cable headend, where as DSL (digital subscriber line) has dedicated access

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15
Q

Hybrid Fiber Coax (HFC)

A

A network architecture that typically uses fiberoptic cables to bring signals to selected areas of the system called nodes, which are usually based on number of subscribers to be served.

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16
Q

Wireless access networks

A

Connects end system to router via base station (“access point”)

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17
Q

Packet switching

A

Where the host breaks application-layer messages into packets

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18
Q

Circuit switching

A

end-end resources allocated to and reserved for “call” between source and destination

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19
Q

What methods are used for resource allocation?

A

Packet switching and Circuit switching

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20
Q

What can a ‘bad guy’ do in network security?

A

Eavesdrop, impersonate, hijack, and DoS.

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21
Q

DoS

A

Denial of service. Attackers make resources (server, bandwidth) unavailable to legitimate traffic by overwhelming resources.

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22
Q

What is packet sniffing?

A

An application/device monitors and reads network packets as they transverse the network. Plaintext/Cleartext can be read.

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23
Q

What is IP spoofing?

A

Sending information into the network with false “Sender IP” information.

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24
Q

Communication links

A

fiber, copper, radio, satellite
transmission rate = bandwidth

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25
What are Networks?
Collection of devices, routers, links: managed by an organization
26
Internet standards (2)
RFC: Request for comments IETF: Internet Engineering Task Force
27
ISP
Internet Service Provider
28
Packet switches
forward packets (chunks of data) e.g. routers and switches
29
IXP
Internet Exchange Point
30
Packet delay formula
d[nodal] = d[proc] + d[queue] + d[trans] + d[prop]
31
d[proc]
Nodal processing - check bit errors, determine output link
32
d[queue]
Queueing delay - time waiting at output link for transmission - depends on congestion level of router
33
d[trans]
Transmission delay
34
d[prop]
Propagation delay
35
Transmission delay formula
d[trans] = L / R L = Length (bits) R = Link Transmission Rate (bits/sec)
36
Propagation delay formula
d[prop] = d / s D = Distance (m) S = Speed (m/s)
37
Traffic intensity formula
(L * a) / R L = packet length (bits) a = average packet arrival rate R = link bandwidth
38
Traceroute program
Provides delay measurement from source to router along end-end internet path towards destination
39
Throughput
Rate at which bits are sent from sender to receiver (in bits/[time unit])
40
Bottleneck link
The link on an end-end path that constrains the end-end throughput
41
Packet "sniffing"
An attack on wireless networks to capture data and register data flows in order to analyze what data is contained in a packet.
42
IP spoofing
When an intruder uses another site's IP address to masquerade as that other site. : injection of a packet with a false source address.
43
Network security lines of defense
Authentication Confidentiality Integrity checks Access restrictions Firewalls
44
[Network security] Authentication
Proving you are who you say you are
45
[Network security] Confidentiality
* Protecting sensitive information from unauthorized access. * Ensuring data privacy and secrecy.
46
[Network security] Integrity checks
Verify the authenticity and completeness of data transmitted over a network. * checking for data corruption, unauthorized modification, ensuring data hasn't been tampered with during transmission. * Common methods: checksums, message authentication codes (MACs), and digital signatures.
47
[Network security] Access restrictions
* Limiting access to authorized users. * authentication, authorization, and encryption. * e.g. Password-protected VPNs
48
[Network security] Firewalls
specialized "middleboxes" in access and core networks: - off-by-default: filter incoming packets to restrict senders, receivers, applications - detecting/reacting to DOS attacks
49
5 Layers of the Internet Protocol Stack
Physical, Data Link, Network, Transport, Application
50
Physical Layer
Transmits raw bit streams over physical media.
51
Data Link Layer
Provides reliable data transfer between nodes on a network.
52
Network Layer
Routes packets between networks.
53
Transport Layer
Provides end-to-end reliable data delivery.
54
Application Layer
Provides services to users, such as email, web browsing, and file transfer.
55
Packet-Switched Networks
Data is divided into packets and routed independently through the network.
56
Circuit-Switched Networks
Dedicated circuit is established between the sender and receiver.
57
Radio link types (5)
- Wireless LAN (WiFi) - Wide-area (e.g. 4G/5G cellular) - Bluetooth - Terrestrial microwave - satellite
58
Peering link
a process by which two Internet networks connect and exchange traffic
59
Content provider network
(e.g, Google); private network that connects its data centers to internet, often bypassing tier-1, regional ISPs
60
Ethernet (speeds)
Wired access at 100Mbps, 1Gbps, 10Gbps
61
WiFi
Wireless access points at 11, 54, 450Mbps
62
IP
Internet Protocol - An addressing system that finds paths to distant computers. Specifies how a router handles a request for another IP address.
63
Network frame
When the network interface card takes the packets and wraps them up and send them out along the cable to the central hub or switch.
64
Data center
Physical or virtual infrastructures used by enterprises to house computer, server and networking systems and components for the company's IT needs
65
OSI Model
Layers: Physical, Data Link, Network, Transport, Session, Presentation, Application Focus: Conceptual framework for network communication. Approach: Vertically layered, clear separation of concerns Protocol Examples: Not tied to specific protocols, but examples include HTTP (Application), SSL/TLS (Presentation), TCP (Transport), IP (Network), Ethernet (Data Link) Usage: Primarily educational and conceptual
66
TCP/IP Model
Layers: Application, Transport, Internet, Network Interface Focus: Practical model based on internet protocols Approach: Horizontally layered, with some overlap in responsibilities Protocol Examples: HTTP, FTP, TCP, UDP, IP, Ethernet Usage: Widely used in real-world network implementations.

CS 335 - Computer Networks (7 decks)

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