Transcript Computer Networking Concepts 2

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Introduction to Networking
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Converged Networks
l Multiple services-multiple networks
l Telephone, radio, television, and computer data networks each
have their own individual versions of the four basic network
elements
l every one of these services required a different technology to carry
its particular communication signal
l each service had its own set of rules and standards to ensure
successful communication of its signal across a specific medium
l Converged networks
l consolidate these disparate networks onto one platform - a platform
defined as a converged network
l voice, video, and data traveling over the same network eliminates
the need to create and maintain separate networks.
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Converged Networks
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Network Architecture
l A wide range of applications
and services
l Different types of physical
infrastructures
l The technologies that
support the infrastructure
and the programmed
services and protocols that
move the messages across
that infrastructure
l Characteristics needed to
meet user expectations
l fault tolerance
l scalability,
l quality of service
l security
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Fault Tolerance
l Availability
l Requires a network architecture that is designed and
built to be fault tolerant
l Limits the impact of a hardware or software failure
l Recover quickly when such a failure occurs
l Redundant links, or paths, between the source and
destination of a message
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Fault Tolerance
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Scalability
l Quick expansion to support new users and applications
l No impact on the performance of the service being
delivered to existing users
l This depends on a hierarchical layered design for the
underlying physical infrastructure and logical architecture
l The operation at each layer enables users or service
providers to be inserted without causing disruption to the
entire network
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Scalability
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Quality of Service
l New applications available to users over internetworks create higher
expectations for the quality of the delivered services
l Voice and live video transmissions require a level of consistent quality
and uninterrupted delivery that was not necessary for traditional
computer applications
l Quality of these services is measured against the quality of
experiencing the same audio or video presentation in person
l Traditional voice and video networks are designed to support a single
type of transmission, and are therefore able to produce an acceptable
level of quality.
l New requirements to support this quality of service over a converged
network are changing the way network architectures are designed and
implemented.
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Quality of Service
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Quality of Service
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Security
l accessible means for
transmission of
business and
personal
communications
l The security
requirements of the
network have
changed
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Client-Server Architecture
l Client: Device requesting information
l Server
l Device responding to the request
l Usually contains information to be shared with many client
systems (web pages, documents, databases, pictures, video,
and audio files)
l Application layer protocols describe the format of the requests
and responses between clients and servers
l Control information, such as user authentication and the
identification of a data file to be transferred
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Client-Server Architecture
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Client-Server Architecture
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Peer-to-peer Architecture
l Two or more devices are connected via a network and can
share resources (such as printers and files) without having
a dedicated server
l Every connected end device (known as a peer) can
function as either a server or a client.
l One computer might assume the role of server for one
transaction while simultaneously serving as a client for
another.
l The roles of client and server are set on a per request
basis.
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Peer-to-peer Architecture
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Network Topology
l Star
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Network Topology
l Ring
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Network Topology
l Bus
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Network Topology
l Mesh
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Logical Topologies
l Broadcast
l each host sends its data to all other hosts on the network medium
l There is no order that the stations must follow to use the network
l It is first come, first serve
l Token passing
l electronic token is passed sequentially to each host
l When a host receives the token, that host can send data on the
network
l If the host has no data to send, it passes the token to the next host
and the process repeats itself.
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Future Directions
l
There are three major trends that are contributing to the future shape of
complex information networks:
l Increasing number of mobile users
l Proliferation of network capable devices
l Mobile devices
l VoIP devices
l Gaming systems
l household and business gadgets that can connect and use network services
l Expanding range of services
l The widespread acceptance of technology and the fast pace of innovation in
network delivered services create a spiraling dependence
l
To meet user demands, new services are introduced and older services are
enhanced.