Welcome to Networking and Security!

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24 Οκτ 2013 (πριν από 3 χρόνια και 9 μήνες)

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Welcome to Networking and
Security!

Brett Tjaden

216 ISAT/CS Building

Department of Computer Science

James Madison University

Harrisonburg, VA 22807

Email: tjadenbc@jmu.edu

Phone: 540
-
568
-
2771

Webpage: https://users.cs.jmu.edu/tjadenbc/Web

Introduction


“[Internetworking] has become a fundamental
part of life.”


Internetworking

is two things:



Idea: Many heterogeneous networks can be
interconnected to function as a coordinated unit



Implementation: A set of
open

communication
conventions (or
protocols
) have been
developed (i.e. TCP/IP)

Network Protocols


Protocol = syntactic and semantic rules for
communication


Open = protocol specifications are publicly
available


Anyone can implement them


Run on lots of different operating systems


Designed to accommodate:


Lots of different networking technologies


Lots of different applications

Internet Services


Many popular and widespread
application
-
level Internet services
(used by
users
):



World Wide Web


Electronic mail


File transfer


Remote login


Etc.

Internet Services (cont)


The Internet’s primary network
-
level services
(used by
network programmers
):



Connectionless packet delivery


Break messages up into small chunks (called
packets
)


Route each packet separately through the network


Reassemble message when all packets reach destination


Reliable stream transport


Handle problems that can occur such as:


Lost or corrupted packets


Other network errors

Distinguishing Features of TCP/IP


Many vendors offer proprietary network
technologies that offer:


Connectionless packet delivery service


Reliable stream transport service


TCP/IP also offers:


Network technology independence


Universal interconnection


End
-
to
-
end acknowledgements


Application protocol standards

Internetworking


How It Works



Protocol Layering



Physical Network

Layer 1

Layer 2

Layer N

Layer 1

Layer 2

Layer N

. . .

. . .

Sender

Receiver

Physical Networks


An internetwork is typically comprised of many
physical networks

over which data travels


There are many different types of physical
networks:


Circuit
-
switched vs. packet
-
switched networks


Local Area Networks (LAN) vs. Wide Area Networks
(WAN)

Circuit
-
Switched Networks



Forms a dedicated connection (circuit)
between the two endpoints


Examples


Advantages


Disadvantages

Packet
-
Switched Network



Data is divided into
packets

and each packet
is routed through the network separately


Examples


Advantages


Disadvantages

Wide Area Networks (WANs)



Provide communication over large distances


Example


Advantages


Disadvantages

Local Area Networks (LANs)



Only spans short distances


Examples


Advantages


Disadvantages

Ethernet


A popular packet
-
switched LAN technology
invented at Xerox PARC in the 1970’s


Components:


The ether


Transceivers


Attachment Unit Interface (AUI) cable


Host Interface

Ethernet (cont)



Ethernet (cont)



Advantages




Disadvantages

Thinnet



A thinner, less expensive, and more flexible
alternative to Ethernet


Components:


The ether


Computers with transceivers and host interface
built in

Thinnet (cont)



Twisted Pair



Very thin, very cheap, very flexible
alternative to Ethernet and Thinnet



Components:


A hub


Computers with host interface built in

Twisted Pair (cont)



Summary


Internetworking

enables many heterogeneous
networks can be interconnected to function as a
coordinated whole


An internetwork is typically comprised of many
physical networks

over which data travels


A popular physical network technology is
Ethernet