R 20 Internetworking Concepts Architecture amp Protocols CECS 474 Computer Network Interoperability Notes for Douglas E Comer Computer Networks and Internets 5 th Edition Tracy Bradley Maples PhD ID: 315189
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CHAPTE
R 20Internetworking:Concepts, Architecture, & Protocols
CECS 474 Computer Network Interoperability
Notes for Douglas E. Comer, Computer Networks and Internets (5th Edition)
Tracy Bradley Maples, Ph.D.
Computer Engineering & Computer Science
California State University, Long BeachSlide2
Why Internetworking
?"One of the most utterly scintillating notions presented in the text is that there is no such thing as an internet. Universal service exists by deftly combining software and hardware into a virtual network system, where the communication system is an abstraction."Dr. Jennifer SeitzerUniversity of Dayton LANs
Low cost Limited distance
WANs High cost
Unlimited distance
Thus, no single networking technology is best for all needs.Slide3
Universal Service
A fundamental concept in networkingPioneered by the telephone systemAllows an arbitrary pair of computers to communicateHighly desirableDifficult in a heterogeneous world Heterogeneity
Incompatibilities among networks exist. There are different:
Electrical propertiesSignaling and data encoding
Packet formats
Physical Addresses
Ultimately
:
Although universal service is highly desirable, incompatibilities among network hardware and physical addressing prevent an organization from building a bridged network that includes arbitrary technologies.
--ComerSlide4
Solution: Build an Internetwork
Begin with heterogeneous network technologiesConnect the physical networksCreate software to make the resulting system appear homogeneous The result is called an internetwork or internet.
Connecting Heterogeneous Networks
Special purpose computer systems are used to connect heterogeneous networks:Dedicated
Work with LAN or WAN technologies
Known as an
-- Internet router
-- Internet gatewaySlide5
An Internet Router
The cloud denotes an arbitrary network technologyOne interface per network is needed Main Concept:
A router can interconnect networks that use different technologies, including different media and media access techniques, physical addressing schemes, or frame formats.--ComerSlide6
Internet Architecture
Use multiple:-- Networks-- Routers interconnecting networksThe Host computer connects to a networkA single router has limited
-- CPU power and memory-- I/O capability
Goal of Internetworking Create a communication system that is:
Seamless
Uniform
General-purpose
Universal
Hides heterogeneity from the userSlide7
The Internet ConceptSlide8
Hiding Heterogeneity
To create a "virtual" network:Invent-- An addressing scheme-- A naming schemeImplement with the scheme with protocol softwareNote: The protocol software is needed on both hosts and routers.
The
Internet Protocols Known as TCP/IP
Many protocols comprise the
suite
Designed to work together
Divided into five conceptual layersSlide9
TCP/IP Layering
Note: This TCP/IP layering is an actual implementation of protocols, unlike the ISO model.Slide10
TCP/IP Layers
Layer 5: Application LayerEverything else (i.e., how one application uses the Internet)Similar to OSI Layer 6 and 7Layer 4: Transport LayerSpecifies how to provide reliable transfer from one application on one computer to an application on another
Similar to OSI Layer
4Layer 3: Internet Layer
Format of packets
Mechanisms for forwarding packets
Not in the OSI
Model
Layer 2: Network
Interface Layer
MAC frame format
MAC addressing
Interface between computer and the network (i.e., the NIC)
Similar to OSI Layer
2
Layer
1:
Physical Layer
Basic network hardware
Similar to OSI Layer 1