Norman notes Until Structured Cabling Flashcards
Computer Networks
the interconnection of a collection of autonomous computers
Advantages of Computer Networks
Resource Enhancement (Sharing)
High speed communications
Cost Balancing (scalable and agile)
Reliable
Availability
Mobility (accessed from anywhere)
Simple network model
Logical connection between two APS comes about by a physical connection of circuits
Protocols
A set of rules that govern the communication between two entities
Categories of protocols
Proprietary
Public
De Jure Standards
De Facto standards
Proprietary Protocols
Device can only communicate with devices of the same protocol
Public protocol
Standardized publicly used protocol such as tcpip
Defacto standards protocols
Standard protocol that comes around due to widespread acceptance
De jure standards
Formal standards by organizations such as IEEE. Ensure QoS
Types of Protocol
Master and slave
Peer to peer
Connection less data gram
Connection oriented virtual circuit
Send and pray
Remote procedural call
Synchronous
Asynchronous
Layered
Monolithic
Heavy
Light
Master and Slave
One device known as master controls all other slave devices
Connectionless data gram
Data is transmitted without establishing dedicated connection. Each packet treated individually, no guarantee they will arrive in order
Connection oriented (VC)
Dedicated connection, packets arrive in order
Send and pray
Transmit data without any error checking
Remote procedural call (rpc)
Program on one pc allowed to execute on another pc over a network
Synchronous
Sender and receiver operate in lockstep
Asynchronous
Data transmitted independently
Layered
System broken down into separate layers that interact through interface
Monolithic
Single tightly coupled unit with no separation between modules
Heavy
Needs a lot of overhead to function
Light
Simple and efficient, less overhead required
What is the function of a protocol
It’s the way two ends of the service exchange data. Uses communication systems to define what each user sees.
Uses classes of service
Classes of service
Connection oriented
Connection less service
Acknowledged connectionless
Unconfirmed connection oriented (send and pray)
Responsibilities of protocols
Data formatting (prepare data)
Address resolution (map address to physical location)
Synchronization (between sender and receiver)
Error detection and correction
Flow control
Routing (select best path)
Segmentation and reconstruction
Congestion control
Access control
Link management
Quality of service
Classifications of networks
WAN / ex the internet
MAN / ex network of schools in city
LAN / ex office network
Propagation delay
Metric used to test packet transmission time over network.
<1 is LAN
~1 is MAN
>1 is WAN
Wan Channel
Supports complete packets so END. nodes never know the state of the network
Lan channel
Only supports small fraction of packets so nodes know state of channel
When connecting lan to wan backbone
Make sure not to alter perception of network for nodes
WANs must:
Be designed and supported as backbone infrastructure
Supply communication links with higher throughput and lower latency channels
Provide wider range of services in an integrated manner without degradation of service
What are MANs
they are wans with lan technology.
Supported by optic tech such as fiber optics
Internetworking
Concerned with connection of local mans and wans to produce highly connected mans and wans
Internetworking elements and why they are needed
Repeaters, routers, gateways
Needed to produce cost effective solutions that overcome physical restrictions
Network topologies
Physical topology is the actual layout of the network,
logical topology is how the data flows through
Considerations when designing network topologies
Max reliability
Route traffic along least cost path
Give end user highest response time and throughput
High availability
All physical topologies are variants of
Point to point and multipoint methods
Multipoint
Multiple devices connected through single communications medium
Physical topologies
Hierarchical
Bus
Ring
Star
Mesh