chptr12 Flashcards
Data
Messages between sender / receiver
Communications Channel
Path for messages between 2 nodes
may include intermediate nodes that forward packets
interfaces at each end may be different
Protocols
Establishes accurate and appropriate meaning to messages
Physical Connection
Independent of the messages
Hosts & end nodes
sender and receiver end points
Message
primary purpose of communication - data - program - file - multimedia - represented digitally
byte stream
term used with data as communications are predominately serial
Packets
Long messages broken down to help with channel availability
takes turns using channels
some can be identified as frame or datagram to identify purpose
Header followed by data
1A, 1B, 1C etc
Links
Segment of communication channel
Bandwidth
Bit rate of overall channel
Medium Guided
communications limited to specific path
Medium Unguided
Not limited to specific path
End Node Interfaces
Wired - Wireless Ethernet - Bluetooth - WiMax - DSL - Cable - Sat Link - Modem etc
Network Topology
Fundamental Layout of Netork
describes path between 2 points
affects availability, speed and traffic
Logical Topology
Operational relationship between the various network components
Physcial Topology
Actual layout of the network wiring
Mesh Topology
Multiple paths between end nodes
1 node failure will slow but not stop as long as other path is available
large networks that use switches & routers are typically partial mesh
Full Mesh Network
Direct Point 2 Point channel connecting every pair of nodes
impractical due to large number of connections needed
Bus Topology
Each node is tapped into the Bus along the Bus
node broadcasts a message that travels the entire bus
every node receives but ignores if not addressee
travels entire medium both directions
termination required at ends of bus to prevent echoing
branches can be added to create tree but still wide broadcast
Bus Network Implementation
req single pair of wires from one end of network to other
cheap - easy to wire
rarely used in new networks except for wireless nets
Star Topology
Primarily for LANS & sometimes connecting satellite offices to central
all nodes connected to a point 2 point device
nodes communicate through central device
switching in central device connects 2 nodes together
central device can steer data from one node to another as req
most modern switches allow mult pairs simultaneously
Failure of central device will kill entire network
Ring Topology
Point 2 Point connection from each node to next
Last node connects to first to create ring
nodes forward messages in loop unidirectional (bidirectional is possible tho)
past popularity ie token ring
Local Area Networks LAN
Network that connects computers etc over a small localized area
Wide Area Network WAN
networks over large distances
Extranet
connection between a business and a business partner
PSTN Public switched telephone networks
large cable companies and other common carrier providers
Private virtual circuits
logical connections of the WAN as a whole
Hub
is a central connection device used to simplify wiring
hub based ethernet
similar to star topology but not smart - it’s passive
service provider
Provides internet connection
wi fi
radio based compativle extension to ethernet standard
switched ethernet
based on star topology, each node connected to central switch that is capable of connecting any 2 nodes together.
backbone networks
used to interconnect several LANs
hierarchical LAN
higher up the backbone network
Routers and gateways
intermediate link connecting nodes from various networks. Converts data format to the next required. Specialized device to interconnect networks and pass packets.
mesh points
extends the range of wireless networks
intranet
web services that are restricted to a group of users
Metropolitan Area Network MAN
network larger in geographical scope than a LAN but within a range of less than 30 miles.
edge & edge router
a router at the edge of the local network, a router would be an edge router
point of presense
ISP has a point of presence in the immediate vicinity to connect to.
Internet backbone
Large ISPS known as national or internation service providers to speed traffic
Network Access Points NAPS
Interchanges on the internet backbone
Piconets or Personal Area Netowrks PANS
separate from other networks, these are created for the presonal use of an individual with a range of 30 ft or less
Packet Routing
packets are passed along the links from node to node.
circuit switching
dedicates a path for exclusive use of the sender receiver pair for the entire length of time of the connection. Inefficient and rarely used
virtual circuit
multi link channel path established for communication between 2 end nodes
permanent virtual circuit PVC
virutal circuit that is created when a network is built
Switched virtual circuit SVC
set up temporarily when a connection is esablished and maintained until the connection is closed
packet switching
aka datagram switching assumes that each packet is routed from node to node independently - shortest path to destination - less traffic
