Quiz 1 Flashcards
WAN
Wide Area Networks
LAN
Local Area Networks
MAN
Metropolitan Area Networks
Communication
the process by which people share ideas, experiences, knowledge and feelings through the transmission of symbiotic messages
Communications model vocab: Source
Generates data to be transmitted
Communications model vocab: Transmitter
Converts data into transmittable signals
Communications model vocab: Transmission Medium
Carries data
Communications model vocab: Receiver
Converts received signal into data
Communications model vocab: Destination or Sink
Take incoming data
Examples of wired transmission mediums
Fiber optic, coaxial cable, unshield twisted pair (UTP)
What is the usual wireless transmission medium?
Electromagnetic energy
PAN
Personal Area Network
Wide Area Networks usually…
- Span a large geographical area
- Cross public rights of way
- Rely in part on common carrier circuits
- Alternative technologies used include:
─ Circuit switching Packet switching
─ Frame relay
─ Asynchronous Transfer Mode (ATM)
Circuit Switching Switching
─ Uses a dedicated communications path established for duration of conversation
─ Comprising a sequence of physical links
─ Dedicated logical channel
─ e.g. Telephone network
Packet Switching
─ Data sent out of sequence
─ Small chunks (packets) of data at a time
─ Packets passed from node to node between source and destination
─ Used for terminal to computer and computer to computer communications
Frame Relay
─ Packet switching systems have large overheads to compensate for errors
─ Modern systems are more reliable
─ Errors can be caught in end system
─ Provides higher speeds with most error control overhead removed
Asynchronous Transfer Mode (ATM)
─ Evolution of frame relay
─ Fixed packet (cell) length with little overhead for error control
─ Anything from 10Mbps to Gbps
─ Constant data rate using packet switching technique with multiple virtual circuits
Local Area Networks
─ Smaller scope (building or small campus)
─ Usually owned by same organization as attached devices
─ Data rates much higher
Metropolitan Area Networks
─ Middle ground between LAN and WAN
─ Private or public network
─ High speed
─ Large area
ARPANET
─ What the internet evolved from
─ First operational packet network
─ Applied to tactical radio & satellite networks
─ Had a need for interoperability
─ Led to standardized TCP/IP protocols
The internet
─ Hosts: interconnected end systems including PCs, workstations, servers, phones, tablets,
etc.
─ Network: most hosts that use the Internet are connected to a network, such as a local area
network (LAN) or a wide area network (WAN)
─ Routers: Those networks are, in turn, connected by routers
Modulation
Representing data with something (ex. Amplitude) (get a new definition)
Guided Transmission Medium
Transmission capacity depends on distance and on weather medium is poin-to-point
Examples: Twisted pair (TP), coaxial cable, optical fiber
Unguided Transmission medium
Example: Wireless
Direct Link
No intermediate devices
Multi-point
More than two devices share a link
Simplex
One direction transmission
Half duplex
Either direction supported, but only one direction at a time
Full duplex
Both directions support at same time
Sine wave
Rate of change: Hz per second, Period = T, T = 1/F
Phase: Relative to positive in time
Electromagnetic spectrum
Wireless mics: 470 - 698 MHz
FM Radio: 88 - 108 MHz
Sirius xx Satellite Radio: 2332.5 MHz - 2345 MHz
Protocol Architecture is needed because…
-Using a common protocols for different tasks makes common rules and conventions.
Protocol Architecture Main Features
-Syntax: Format of data blocks
-Semantics: Control info for coordination and error handling
-Timing: Speed match and sequencing
-Breaks down complex tasks into subtasks. Each of these subtasks are implemented separately as layers.
-Vertical stack.
Layers Of Protocol Architecture
-Each layer performs a related subset of functions required to communicate with (an)other system(s).
-Higher layers depend on lower levels for primitive functions and to conceal details of those functions. (Lower layers are expected to provide services to higher levels)
-When a change is made to one layer then there should be no changes to another layer.
TCP/IP Protocol Architecture
-Developed by DARPA for ARPANET
-5 Layers: (5) Application Layer, (4) Transport Layer, (3) Internet Layer, (2) Link Layer, (1) Physical Layer
TCP/IP: Physical Layer
-Communication theory: Phy layer sends individual bits from one node to a directly connected node
-Contains physical interface between the data transmission device and the transmission medium
-Examples: Ethernet uses guided wired medium, LAN uses electromagnetic waves
TCP/IP: Link Layer
-Exchanges data between two or more directly connected devices (examples: PCs, routers, etc)
-Packets in linked layer = frames
-Uses MAC addresses for multiple access
-Examples: Point-to-point Protocol (PPP), Ethernet: IEEE 802.3, Wireless LAN: IEEE 802.11 (a/b/g/n/ac)
TCP/IP: Internet Layer
-Responsible for moving network layer packets from one host to another host
-Internet Layer Packets = datagrams
-IP Protocol: Defines the format of datagrams and how end systems and routers act on the datagram
-Routing Protocol: Determine routes that datagrams take between sources and destinations
-This layer routes datagrams through a series of packet switches called routers between the source and destination
TCP/IP: Transport Layer
TCP/IP: Application Layer
