lecture 2 Flashcards

1
Q

3 kinds of data flow

A
  1. simplex
  2. half duplex
  3. full duplex
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2
Q

describe a simplex data flow

A
  • one way flow

- A sends to B

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3
Q

describe a half duplex data flow

A
  • two way flow
  • one at a time
  • A sends to B
  • B sends to A
    e. g fibre optics
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4
Q

describe a full duplex data flow

A
  • A and B can send to each other simultaneously
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5
Q

what is a subnet

A

everything between the hosts

e.g the routers,

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6
Q

what is a host or end-system

A
  • a computer that a user logs into to do work

- attached to network, not part of network (usually)

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7
Q

3 ways to classify networks

A
  • transmission technology
  • size
  • topology
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8
Q

3 kinds of transmission technology

A
  1. broadcast
  2. multicast
  3. unicast (p2p)
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9
Q

describe broadcast transmission

A
  • one to all
  • in bus topology everybody receives it but ignore it and only destined receiver will respond
  • a 0 bit is broadcast
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10
Q

describe multicast transmission

A
  • communication with specified groups
  • a 1 bit is multicast
  • uses a GID (group ID)
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11
Q

describe unicast transmission
(p2p, end to end, host to host)
(3)

A
  • links between nodes
  • from source to destination: visit one or more nodes
  • uses protocols to optimize routing (find best path)
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12
Q

large networks tend to use what kind of transmission technology and why?

A
  • UNICAST (P2P)
    e.g internet, sending an email
    why?
  • decrease collisions and traffic
  • increase efficiency
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13
Q

where do routing algorithms play an important role (broadcasting, multicasting, P2P)?

A

UNICAST (P2P)

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14
Q

4 types of network structures

A
  • LAN (10m to 1Km)
  • MAN (10km, city)
  • WAN (100km - countries, continents, planets)
  • Wireless
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15
Q

why do we need to classify network structures, what changes?

A
  • protocols used
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16
Q

LANs (6)

A
  • used in small geographic regions
  • high data rates (min: 10-100Mbps ++)
  • low cost
  • typically use BROADCAST transmission technology
  • can be used a testing environment for other protocols
  • IEEE 802.3
17
Q

in LAN bus topology, what protocol do we use to transmit

A

CSMA

- to make sure corresponding node is not broadcasting, otherwise collision happens

18
Q

ad hoc network (4)

A
  • no router
  • connecting devices directly
  • similar to hotspot/bluetooth
  • IoT uses this tech
19
Q

MANs (4)

A
  • used in medium size geographic regions
  • does not use switching elements, single wires instead
  • e.g. is cable TV
  • IEEE 802.6 (DQDB)
  • slower than a LAN (bigger)
20
Q

what is dual queue dual bus?

A
  • used in MANs

- uses two unidirectional broadcast buses with different directions

21
Q

WANS (4)

A
  • used in large geographic regions
  • low data rates (hella big)
  • high cost
  • uses transmission lines and switches, routers and hubs
  • e.g. Internet
22
Q

examples of wireless networks

A
  • bluetooth

- flying LAN in airplanes

23
Q

6 types of topologies

A
  • bus
  • ring
  • tree
  • star
  • mesh
  • hybrid
24
Q

if we have bidirectional bus flow

A
  • use baseband cable and repeater
25
bus pros (2) and cons (3)
pros - Requires less cable length this less cost - Easy to set up for small networks cons - Adding nodes/devices can slow the network (high traffic) - Troubleshooting is not easy because all devices are connected to a central cable - If central cable (bus) fails, then the network fails
26
how can we fix a unidirectional ring
- add an extra ring to make it bidirectional
27
best case and worst case in uni ring
``` best= A to B 1 links/hop worst= A to last one n - 1 links/hops n = number of nodes ```
28
best, average, worst case in bi ring
best: 1 average= n+2/4 worst= n/2
29
what network structure uses tree topology
MANs
30
star pros and cons
Pros: - Easy to troubleshoot - Devices can be easily added/removed without affecting overall connectivity and performance Cons: - If the central hub fails, then the whole network is disrupted (it is centralized) - Devices can only be added depending on the number of outlets present in the hub
31
bi star pros (3) and cons (2)
Pros: - Can provide an alternative path in the case of failure of 1 node - Minimal packet collisions - High speed of data transfer Cons: - Addition/removal of nodes is difficult - Failure of two adjacent nodes can disrupt the network
32
uni star pros (1) and cons (2)
Pros: - Less packet collisions Cons: - If one node fails, the whole network is disrupted since data packets can only be moved in one direction - Adding/removing nodes without interfering with the network is difficult
33
what topologies use broadcast
- bus | - ring
34
mesh pros and cons
Pros - Many alternative paths Cons: - Hella costly to make and add (NOT SCALABLE)
35
types of connections
- P2P: station to station | - Multipoint: mainframe to many stations
36
switched WAN vs p2p WAN
- switched: going through multiple WAN networks before reaching destination - p2p
37
best, average, worst case in star
``` best= 2 average= n+2/4 worst= 2 ```
38
best, average, worst case in mesh
``` best= 1 average= 1 worst= 1 ```