1.4 architectures

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1.4 ON ARCHITECTURES

Architectures cover many different aspects of networking environments.

Service Architecture: The Basic framework of services by network .

Protocol Stack Architecture:Service delivery functions andboundaries

Router Architecture: specialized computer with hardware/software forpacket processing , processing of routing protocols & configurationrequirements.

Network Topology Architecture:For efficient operation & service toits users, a network topology architecture is needed

It is scalable and allows growth.

NetworkManagement Architecture:

Management plane handles the configuration responsibility of a network

control planeaddresses routing information exchanges.


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1.5 SERVICE ARCHITECTURE It is much like the postal delivery system.

The three service models associated with IP networks are:

BEST-EFFORT SERVICE ARCHITECTURE

A packet or a datagram is forwarded from one router to anothertowards destination.

For this IP network uses packet switching. The packet forwarding without worrying about reliable delivery. Two consecutive packets that belong to the same connection are to

be treated independently by a router. IP makes its best effort to deliver packets. Because of this, the IP

service paradigm is referred to as the best-effort service.


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INTEGRATED SERVICES ARCHITECTURE

Developed in the early 1990s

It allows functionalities for services that are real-time, interactive, and that cantolerate

some loss, but require a bound on the delay ,

bandwidth guarantee and a dedicated path.

For example, interactive voice and multimedia applications fall into this category.

Note that the basic best-effort IP framework works on the notion of statelessness; that is, two consecutive packets

that belong to the same connection are to be treated independently by a router.

It require a connection or a session for a certain duration of time, duration.

Since the basic IP architecture works on the notion of statelessness, and it was

infeasible


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DIFFERENTIATED SERVICES ARCHITECTURE

diff-serv architecture was developed to provide prioritizedservice mechanisms without requiring connection-levelinformation to be maintained at routers.

Specifically, this approach gives priority to services by marking IPpackets with diffserv

code points located in the IP header. Routers along the way then check the diff-serv code point and

prioritize packet processing and forwarding for different classes ofservices.

Diff-serv code points are identified through a 6-bit field in the IPv4

packet header; in the IPv6 packet header, the traffic class field is used for the

same purpose.


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SUPPLEMENTING A SERVICE ARCHITECTURE

In a realistic sense, and to provide acceptable quality of service

performance, the basic concept can be supplemented withadditional mechanisms to provide an acceptable servicearchitecture,

For example, although the basic conceptual framework does notrequire it, a router can be designed to do efficient packetprocessing for packets that belong to the same web-page

requested by a user since they are going to the same destination. That is, a sequence of packets that

belongs to the same pair of origination and destination IPaddresses, to the same pair of source and destination portnumbers, and to the same transport protocol (either TCP or UDP)

can be thought of as a single entity and is identified as a micro

flow. Thus, packets belonging to a particular microflow can betreated in the same manner by a router once a decision onforwarding is determined based on the first packet for thismicroflow.

Another way to fine-tune the best-effort service architecture isthrough traffic engineering.


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CONTINUED..

That is, a network must have enough bandwidth so thatdelay or backlog can be minimal, routers must haveadequate buffer space, and so on, so that traffic movesefficiently through the network.

In fact, both packet processing at a router and trafficengineering work in together for providing efficient services.

Similarly, for both integrated-services and differentiated-service architecture, packet handling can be optimized at arouter. Furthermore, traffic engineering can be geared forintegrated services or differentiated services architectures.


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1.6 PROTOCOL STACK ARCHITECTURE1.6.1 OSI REFERENCE MODEL FIGURE: The OSI reference model and the IP reference model.


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1.6 PROTOCOL STACK ARCHITECTURE


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PROTOCOL LAYERING IN IP


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ROUTER ARCHITECTURE: A FUNCTIONAL VIEW.


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NETWORK MANAGEMENT ARCHITECTURE: DATA PLANE, CONTROL PLANE, ANDMANAGEMENT PLANE.


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1.4 architectures

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