Ad-hoc TPE kursus: Datanet

Ad
-
hoc TPE kursus: Datanet

Formål:



At give den studerende viden om grundlæggende begreber,
principper og teknikker i moderne datanet(Internettet).



At eksemplificere anvendelse af 2 meget anvendte protokoller i
(programmeringssproget) C


Indhold :




Basale netværksbegreber (MM1)


-

Protokolbegreber, OSI
-
modellen versus TCP
-
implementationen


-

Lag 1 og 2: basal datatransmission, MAC, LLC, Ethernet, HDLC





Adressering i netværk (MM2)


-

IPv4/IPv6


-

Name Services(DNS)




Internet services og protokoller (MM3)


-

Datagram og forbindelses orienteret service


-

Protokoller: IP, UDP, TCP


-

Service primitiver, Tilstandsmaskine model





Protokol programmering (MM4 & 5)


-

TransportLayerInterface


-

Berkeley Sockets, TCP primitiver og eksempler


-

UDP primitiver og eksempel

Local Area Networks

Two broadcast networks

•
(a)

Bus : Ethernet collision prone

•
(b)

Ring : ArcNet collision free

Issues:

Topology

Arbitration

Allocation

Wide Area Networks

•
Relation between hosts on LANs and the
subnet.

Wide Area Networks (2)

•
A stream of packets from sender to receiver.



Store & Forward = Packet Switched




Routing

Network Software

•
Protocol Hierarchies

•
Design Issues for the Layers

•
Connection
-
Oriented and Connectionless Services

•
Service Primitives

•
The Relationship of Services to Protocols

Network Software

Protocol Hierarchies

•
Layers, protocols, and interfaces

Protocol Hierarchies (2)

•
The philosopher
-
translator
-
secretary
architecture.

Protocol Hierarchies (3)

•
Example information flow supporting virtual
communication in layer 5.

Design Issues for the Layers

•
Addressing

•
Error Control

•
Flow Control

•
Multiplexing

•
Routing

Connection
-
Oriented and Connectionless
Services

•
Six different types of service.

Service Primitives

•
Five service primitives for
implementing a simple connection
-
oriented service.

Service Primitives (2)

•
Packets sent in a simple client
-
server interaction on a connection
-
oriented network.

Services to Protocols
Relationship

•
The relationship between a service and a
protocol.

Reference Models

•
Reference Model Design Principles

•
The OSI Reference Model

•
The TCP/IP Reference Model

•
A Comparison of OSI and TCP/IP

•
A Critique of the OSI Model and Protocols

•
A Critique of the TCP/IP Reference Model

Reference Model Design
Principles

1.
Each layer should perform a well
-
defined function.

2.
The function of each layer should be chosen with an eye
toward defining internationally standardized protocols.

3.
The layer boundaries should be chosen to minimize the
information flow across the interfaces.

4.
A layer should be created where a different abstraction is
needed.

5.
The number of layers should be large enough that distinct
functions need not be thrown together in the same layer out of
necessity and small enough that the architecture does not
become unwieldy.

Reference Models

The OSI
reference
model.

Reference Models (2)

•
The TCP/IP reference model.

Reference Models (3)

•
Protocols and networks in the TCP/IP
model initially.

Comparing OSI and TCP/IP
Models

Concepts central to the OSI model

•
Services

•
Interfaces

•
Protocols

A Critique of the OSI Model and
Protocols

Why OSI did not take over the world

•
Bad timing

•
Bad technology

•
Bad implementations

•
Bad politics

Bad Timing

•
The apocalypse of the two elephants.

A Critique of the TCP/IP Reference
Model

Problems:

•
Service, interface, and protocol not distinguished

•
Not a general model

•
Host
-
to
-
network “layer” not really a layer

•
No mention of physical and data link layers

•
Minor protocols deeply entrenched, hard to
replace

Hybrid Model

•
The hybrid reference model to be used in
this book.

Example Networks

•
The Internet

•
Connection
-
Oriented Networks:



X.25, Frame Relay, and ATM

•
Ethernet

•
Wireless LANs: 802:11

Internet Usage

Traditional applications (1970
–

1990)

•
E
-
mail

•
News

•
Remote login

•
File transfer

New applications (1990
–

)

•
WWW

•
Too much to mention

Architecture of the Internet

•
Overview of the Internet.

Ethernet

•
Architecture of the original Ethernet.

•
Dorado @ Xerox Parc (84)

Ethernet

•
Ethernet Cabling

•
Manchester Encoding

•
The Ethernet MAC Sublayer Protocol

•
The Binary Exponential Backoff Algorithm

•
Ethernet Performance

•
Switched Ethernet

•
Fast Ethernet

•
Gigabit Ethernet

•
IEEE 802.2: Logical Link Control

•
Retrospective on Ethernet


Ethernet MAC Sublayer Protocol

Frame formats.
(a)

DIX Ethernet,
(b)

IEEE 802.3.



Ethernet MAC Sublayer Protocol (2)



Ethernet Performance


Efficiency of Ethernet at 10 Mbps with 512
-
bit slot times.

IEEE 802.2: Logical Link Control

(a)

Position of LLC.
(b)

Protocol formats.