Transcript Chapter 13 slides

COMPUTER SYSTEMS
An Integrated Approach to Architecture and Operating Systems
Chapter 13
Fundamentals of Networking and
Network Protocols
©Copyright 2008 Umakishore Ramachandran and William D. Leahy Jr.
13.1 Preliminaries
• Today a general purpose computer not
connected to the "net" or some net is almost
unthinkable.
• Connecting to a network requires an I/O
device which will use DMA
13.2 Basic Terminologies
• Computer connected to a network is called a host
• The connection is made using a device called a
Network Interface Card or NIC
• What exactly is the
"network" shown in the
diagram?
• As we shall see it may be
one network or a
composite of multiple
networks
13.2 Basic Terminologies
• What is the Internet? Consider the postal system…
13.2 Basic Terminologies
• Now consider an email
13.2 Basic Terminologies
• Each cloud represented computers of an
Internet Service Provider (ISP)
• The ISP clouds are not directly connected
• Instead they are connected by routers, which
are special purpose computer for this purpose
• How do these routers know where to send
information? A universal system of addresses
called Internet Protocol (or IP) Addresses is
part of the answer
13.2 Basic Terminologies
• We showed connecting using a cable or phone
network. Connections may also be made
through Local Area Networks (LAN's)
• Other hardware devices
– hubs/repeaters
– bridges
– switches
– routers
13.3 Networking Software
• Need to address issues such as
– Arbitrary message size and physical limitations of
network packets
– Out of order delivery of packets
– Packet loss in the network
– Bit errors in transmission
• Software is logically in a protocol stack
configuration
13.3 Networking Software
• A protocol is the set of rules used to describe all
of the hardware and (mostly) software
operations used to send messages from
Processor A to Processor B
• A protocol describes the syntax, semantics and
timing of communication between two devices
• Common practice is to attach headers/trailers to
the actual payload forming a packet or frame.
13.3.1 Need for a Layered
Protocol Stack
• Good abstraction
• Simpler to understand than OGP
• Easier to design, analyze, implement and test
• Design concept is suites or families
• What do we mean by layers? Or a layered
protocol? Consider the army…
13.3.1 Need for a Layered
Protocol Stack
General
Colonel
Captain
Sergeant
Private
General
Colonel
Captain
Sergeant
Private
13.3.2 Internet Protocol Stack
Application
Transport
Network
Link
Physical
Layer 5
Layer 4
Layer 3
Layer 2
Layer 1
13.3.2 Internet Protocol Stack
• Application: HTTP, SMTP, FTP, etc. Shield applications
using network from network details
• Transport: Breaks message into packets, handles things
like out of order packets, may deal with reliability
• Network: Responsible for routing, does best effort
delivery
• Link: Moves the packet using a protocol such as
Ethernet, Token Ring, and ATM
• Physical: Responsible for physically (electrically,
optically, etc.) moving the bits of the packet from one
node to the next.
13.3.2 Internet Protocol Stack
• Application: HTTP, SMTP, FTP, etc. Shield applications
using network from network details
• Transport: Breaks message into packets, handles things
like out of order packets, may deal with reliability
• Network: Responsible for routing, does best effort
delivery
• Link: Moves the packet using a protocol such as
Ethernet, Token Ring, and ATM
• Physical: Responsible for physically (electrically,
optically, etc.) moving the bits of the packet from one
node to the next.
13.3.2 Internet Protocol Stack
Manufacturers group their protocol software together into a
family and give it a nice name…
•
•
•
•
•
•
Novell Corporation
Banyan Systems
Apple Computer
Digital Equipment
IBM
“The Internet Biggie”
•
•
•
•
•
•
Netware
VINES
AppleTalk
DECNET
SNA
TCP/IP
13.3.2 Internet Protocol Stack
• Layer 5: Application-Sends application specific
messages
• Layer 4: Transport-Sends segments
• Layer 3: Network-Sends packets
• Layer 2: Datalink-Sends frames
• Layer 1: Physical-Sends bits
13.3.2 Internet Protocol Stack
13.4 Transport Layer
• Assume
– send (destination-address, message)
– receive (source-address, message)
• Functionality of transport layer
– Support arbitrary message size at the application
level
– Support in-order delivery of messages
– Shield the application from loss of messages
– Shield the application from bit errors in
transmission.
13.4 Transport Layer
13.4.1 Stop and wait protocols
• Simple approach
– Sender sends a packet and waits for a positive
acknowledgement, commonly referred to as an ACK.
– As soon as packet is received, recipient generates and
sends an ACK for that packet. ACK should contain
information for sender to discern unambiguously packet
being acknowledged. Sequence number is unique
signature of each packet. Thus, all that needs to be in ACK
packet is sequence number of received packet.
– Sender waits for a period of time called timeout. If within
this period, it does not hear an ACK, it re-transmits the
packet. Similarly, the destination may re-transmit the ACK,
if it receives the same packet again (an indication to the
receiver that his ACK was lost en route)
13.4.1 Stop and wait protocols
13.4.1 Stop and wait protocols
13.4.1 Stop and wait protocols
RTT = Round Trip Time
13.4.2 Pipelined protocols
(a)
(b)
13.4.3 Reliable Pipelined Protocol
13.4.3 Reliable Pipelined Protocol
Increasing sequence numbers
Active window of
sequence numbers
Packets sent and acknowledged
Packets sent but not yet acknowledged
Packets that are in the active window that can
be sent without waiting for any further ACKs
Packets that cannot yet be sent since they
are outside the active window
13.4.4 Dealing with transmission
errors
• Methods are needing to determine if packets
are being received correctly
• Examples
– Checksums
– Error Correcting Codes (ECC)
13.4.5 Transport protocols on the
Internet
Transport Features
protocol
Pros
Cons
TCP
Connectionoriented; selfregulating; data
flow as stream;
supports
windowing and
ACKs
Reliable; messages
arrive in order; wellbehaved due to selfpolicing
Complexity in connection
setup and tear-down; at a
disadvantage when mixed
with unregulated flows; no
guarantees on delay or
transmission rate
UDP
Connection-less;
unregulated;
message as
datagram; no ACKs
or windowing
Simplicity; no frills;
especially suited for
environments with
low chance of packet
loss and applications
tolerant to packet loss;
Unreliable; message may
arrive out of order; may
contribute to network
congestion; no guarantees
on delay or transmission
rate
13.4.5 Transport protocols on the
Internet
Application
Web browser
Key requirement
Reliable messaging; in order arrival of
messages
Transport protocol
TCP
Instant messaging
Reliable messaging; in order arrival of
messages
TCP
Voice over IP
Electronic Mail
Electronic file
transfer
Low latency
Reliable messaging
Reliable messaging; in order delivery
Usually UDP
TCP
TCP
Video over Internet
Low latency
File download on
P2P networks
Reliable messaging; in order arrival of
messages
Usually UDP; may
be TCP
TCP
Network file service
on LAN
Reliable messaging; in order arrival of
messages
Remote terminal
access
Reliable messaging; in order arrival of
messages
TCP; or reliable
messaging on top
of UDP
TCP
13.5 Network Layer
• Why a separate layer?
– Multiple network connections to the host
– Multiple hops between source and destination
– Route is not static
• Transport/network layers interface
– Destination address and packet size
• Network layer functionality (host)
– Routing algorithms
– Provide a service model to the transport layer
– Pass it up to transport if destination reached
• Network layer functionality (Routers)
– Routing algorithms
13.5.1 Routing Algorithms
13.5.1 Routing Algorithms
Iteration New node
Count
to which
least-cost
route
known
Init
1
2
3
4
5
A
AC
ACB
ACBD
ACBDE
ACBDEF
B
Cost/
route
2/AB
2AB
2/AB



C
Cost/
route
1/AC
1/AC




D
Cost/
route
4/AD
3/ACD
3/ACD
3/ACD


E
Cost/
route
5/AE
4/ACE
3/ABE
3/ABE
3ABE

F
Cost/
route

6/ACF
6/ACF
5/ADF
4/ABEF
4/ABEF
13.5.1 Routing Algorithms
Destination
A
B
C
F
A
5(EA)
3(BA)
4(ECA)
5(EFDCA)
B
7(EAB)
1(EB)
5(ECB)
6(EFDCB
C
6(EAC)
3(EBC)
3(EC)
4(EFDC)
D
8(EACD)
4(EBEFD)
5(ECD)
2(EFD)
F
9(EABEF)
2(EBEF)
7(ECBEF)
1(EF)
DV Table for Node E
13.5.1 Routing on the Internet
•
•
•
Network of networks
Scale, dynamism
Autonomous Systems (AS)
–
–
Allows for evolution
Gateway node for inter-AS routing
Details of the network layer in a gateway node
13.5.1 Hierarchical Routing Algorithms
Gateway nodes use BGP
Nodes within AS use LS or DV
BGP Border Gateway Protocol
13.5.2 Internet Addressing
Telephone Number
Internet Protocol Address
24 bits
8 bits
IP Network
Device
13.5.2 Internet Addressing
• Consider this 32 bit IP Address
– (10000000 00111101 00010111 11011000)2
• Convert each 8-bit octet into a decimal
number and separate each with a decimal
– 128.61.23.216
• In this address the first 24 bits are network
while the last 8 are the device
– 128.61.23.216/24
13.5.2 Internet Addressing
How many IP networks?
13.5.2 Internet Addressing
How many IP networks?
13.5.2 Internet Addressing
8 bits
24 bits
Device
Device
16 bits
16 bits
IP Network
Device
24 bits
8 bits
IP Network
Device
13.5.3 Network Service Model
Circuit Switching
13.5.3 Network Service Model
MessageSwitching
13.5.3 Network Service Model
Packet Switching
13.5.4 Network Layer Summary
Network
Terminology
Circuit switching
TDM
FDM
Definition/Use
A network layer technology used in telephony. Reserves the network
resources (link bandwidth in all the links from source to destination) for the
duration of the call; no queuing or store-and-forward delays
Time division multiplexing, a technique for supporting multiple channels on a
physical link used in telephony
Frequency division multiplexing, also a technique for supporting multiple
channels on a physical link used in telephony
Packet switching
A network layer technology used in wide area Internet. It supports best effort
delivery of packets from source to destination without reserving any network
resources en route.
Message switching Similar to packet switching but at the granularity of the whole message (at the
transport level) instead of packets.
Switch/Router
Input buffers
Output buffers
Routing table
A device that supports the network layer functionality. It may simply be a
computer with a number of network interfaces and adequate memory to serve
as input and output buffers.
These are buffers associated with each input link to a switch for assembling
incoming packets.
These are buffers associated with each outgoing link from a switch if in case
the link is busy.
This is table that gives the next hop to be used by this switch for an incoming
packet based on the destination address. The initial contents of the table as
well as periodic updates are a result of routing algorithms in use by the
network layer.
13.5.4 Network Layer Summary
Network
Terminology
Delays
Definition/Use
Store and
forward
This delay is due to the waiting time for the packet to be fully formed in the
input buffer before the switch can act on it.
The delays experienced by packets in a packet-switched network
Queuing
This delay accounts for the waiting time experienced by a packet on either the
input or the output buffer before it is finally sent out on an outgoing link.
Packet loss
This is due to the switch having to drop a packet due to either the input or the
output buffer being full and is indicative of traffic congestion on specific
routes of the network.
This is the contract between the network layer and the upper layers of the
protocol stack. Both the datagram and virtual circuit models used in packetswitched networks provide best effort delivery of packets.
This model sets up a virtual circuit between the source and destination so that
individual packets may simply use this number instead of the destination
address. This also helps to simplify the routing decision a switch has to make
on an incoming packet.
This model does not need any call setup or tear down. Each packet is
independent of the others and the switch provides a best effort service model
to deliver it to the ultimate destination using information in its routing table.
Service Model
Virtual Circuit
(VC)
Datagram
13.6 Link Layer and Local Area
Networks
• Innovations in the link layer in the 70's led to
making the internet a household term
• Link layer is responsible for acquiring physical
medium for transmission, and sending packet
over the physical medium to destination host.
• Broad Classification
– Random Access: Example-Ethernet
– Taking Turns: Example-Token Ring
• Portion of protocol that deals with gaining access
to physical medium is called the Media Access
and Control (MAC) layer
13.6.1 Ethernet
No collision
Collision
Detected
Medium
Idle
Need to
Transmit
Listen for
Carrier
Transmit
Message
Medium
Not Idle
Abort
Transmission
Transmission
Complete
Terminologies
•
•
•
•
Base band signaling
Manchester encoding
CSMA/CD
CSMA/CA
– Hidden terminal problem
– RTS/CTS
Joe
• xBASEy
• Watch
– Triumph of the Nerds (PBS show)
Cindy
Bala
13.6.1 Manchester Encoding
0
1
1
0
0
1
0
1
1
13.6.1 Ethernet
Hidden Terminal Problem
13.6.2 Token Ring
Comparison
Link
Features
Layer
Protocol
Pros
Cons
Ethernet Member of random access
protocol family;
opportunistic broadcast
using CSMA/CD;
exponential backoff on
collision
Token
Member of taking turns
ring
protocol family; Token
needed to transmit
Simple to
manage; works
well in light
load
Too many
collisions
under high
load
Fair access to
all competing
stations; works
well under
heavy load
Unnecessary
latency for
token
acquisition
under light
load
13.6.3 Other link layer protocols
• FDDI: Fiber Distributed Data Interface
– Fiber optics based
– High bandwidth backbone used to connect LAN's
• ATM: Asynchronous Transfer Mode
– Guarantees quality of service using link reservation and
admission control to avoid congestion
– Connection oriented and can have transport layer
implemented on top of it
– Used in MAN's and WAN's
• PPP: Point to Point
– Used by dial-up connections
– Widespead
13.6.3 Other link layer protocols
• Ethernet is really not just one protocol. As
obsolescence approaches a new version is
introduced and typically comes out on top
• FDDI was upstaged by Gigabit Ethernet
• ATM is likely to be upstaged by 10-Gigabit
Ethernet
13.7 Relationship between the three
layers
• Both TCP and IP include error checking
– They don't have to be used together
• Most layers are in software but the link layer is
often implemented in hardware
13.8 Data structures for packet
transmission
/* Packet Header Data Structure
*/
struct header_t {
int destination_address; /* destination address
*/
int source_address;
/* source address
*/
int num_packets;
/* total number of
*/
/* packets in message
*/
int sequence_number;
/* sequence number of
*/
/* this packet
*/
int packet_size;
/* size of data
*/
/* contained in the
*/
/* packet
*/
int checksum;
/* for integrity check of */
/* this packet
*/
};
13.8 Data structures for packet
transmission
/* Packet Data Structure */
struct packet_t {
struct header_t header; /*
char *data;
/*
/*
/*
};
packet header */
pointer to the memory */
buffer containing the data */
of size packet_size */
13.9 Message transmission time
P1
P2
Protocol
Protocol
stack
stack
S
msg
pkt1
…
pkt2
Tw
pktn
Network
Tf
R
13.9 Message transmission time
Sender
Overhead
Time on
the wire
Time of
Flight
Receiver
Overhead
13.10 Protocol Layering
• Layering is a structuring tool for combating complexity
of protocol stack
• Allows partitioning total responsibility for message
transmission and reception among various layers.
• Modularity allows integration of a new module at a
particular layer with minimal changes to the other
layers.
• It might appear that a potential downside to layering
might be a performance penalty, as the message has to
traverse several layers.
• Judicious definition of interfaces between layers avoids
such inefficiencies.
13.10.1 OSI Model
7
Application
6
Presentation
5
4
3
2
1
Session
Transport
Network
Data Link
Physical
• Presentation layer subsumes
user directed input/output
functionalities that are
common across different
applications.
• Session layer maintains
process-to-process
communication details and
provides a higher-level
abstraction between an
application and the
transport layer (e.g. Unix
socket).
13.10.2 Practical issues with layering
7
Application
6
Presentation
5
4
3
2
1
Telnet, FTP, etc.
5
TCP
4
IP
3
Ethernet Card
2
Physical
1
Session
Transport
Network
Data Link
Physical
13.11 Networking Hardware
• Hub/Repeater
Hub
13.11 Networking Hardware
• More Hubs
Hub
Hub
Hub
Hub
Hub
13.11 Networking Hardware
• Bridge
1
3
HUB
2
Collision domain
BRIDGE
HUB
4
Collision domain
13.11 Networking Hardware
• Switch
13.11 Networking Hardware
• VLAN
5
1
Switch
Switch
6
2
4
3
8
7
13.11 Networking Hardware
• NIC
MAC address
Header
Message
Payload
13.11 Networking Hardware
• Router
MAC address of router
IP address of the destination
Message
Payload for destination node
Payload for the router
13.11 Networking Hardware
Name of
Definition/Function
Component
Host
A computer on the network; this is interchangeably
referred to as node and station in computer networking
parlance
NIC
Network Interface Card; interfaces a computer to the
LAN; corresponds to layer 2 (data link) of the OSI
model
Port
End-point on a repeater/hub/switch for connecting a
computer; corresponds to layer 1 (physical) of the OSI
model
Collision
Term used to signify the set of computers that can
domain
interfere with one another destructively during message
transmission
Repeater
Boosts the signal strength on an incoming port and
faithfully reproduces the bit stream on an outgoing port;
used in LANs and WANs; corresponds to layer 1
(physical) of the OSI model
13.11 Networking Hardware
Name of
Component
Hub
Definition/Function
Bridge
Connects independent collision domains, isolating them from one
another; typically 2-4 ports; uses MAC addresses to direct the message on
an incoming port to an outgoing port; corresponds to layer 1 (physical) of
the OSI model
Similar functionality to a bridge but supports several ports (typically 432); provides expanded capabilities for dynamically configuring and
grouping computers connected to the switch fabric into VLANs;
corresponds to layer 1 (physical) of the OSI model
Essentially a switch but has expanded capabilities to route a message
from the LAN to the Internet; corresponds to layer 3 (network) of the OSI
model
Virtual LAN; capabilities in modern switches allow grouping computers
that are physically distributed and connected to different switches to form
a LAN; VLANs make higher level network services such as broadcast and
multicast in Internet subnets feasible independent of the physical location
of the computers; corresponds to layer 1 (physical) of the OSI model
Switch
Router
VLAN
Connects computers together to form a single collision domain, serving as
a multi-port repeater; corresponds to layer 1 (physical) of the OSI model
13.12 Network Programming
P1
P2
Socket
13.12.1 Unix Sockets
•
•
•
•
Socket: create an endpoint of communication
Bind: bind a socket to a name or an address
Listen: listen for incoming connections on the socket
Accept: accept an incoming connection request on a
socket
• Connect: send a connection request to a name (or
address) associated with a remote socket
• Recv: receive incoming data on a socket from a remote
peer
• Send: send data to a remote peer via a socket
13.13 Network Services and Higher
Level Protocols
P1
P2
foo (args)
foo (args)
RPC
return
Host 1
Host 2
13.13 Network Services and Higher
Level Protocols
User
fopen
Unix file system
Unix file system
NFS server
NFS client
RPC layer at client
RPC layer at server
Network
13.15 Historical Perspective
•
•
•
•
From Telephony to Computer Networking
Evolution of the Internet
PC and the arrival of LAN
Evolution of LAN
13.15.1 From Telephony to Computer
Networking
• 1875 Telephone invented…analog system
• 1960 Telephone infrastructure goes digital
13.15.1 From Telephony to Computer
Networking
• 1940's Mainframe computers developed
• 1960's Transition
– Batch-oriented card-input/output
– CRT I/O and timesharing
13.15.1 From Telephony to Computer
Networking
Digital Data
Analog Data
?Missing Link?
Telephone
Telephone
Infrastructure
Infrastructure
?Missing Link?
Analog Data
Digital Data
13.15.1 From Telephony to Computer
Networking
Digital Data
Analog Data
MODEM
Telephone
Telephone
Infrastructure
Infrastructure
MODEM
Analog Data
Digital Data
13.15.1 From Telephony to Computer
Networking
• 1968/9 Carterphone decision allowed devices
which were beneficial and not harmful to the
network to be connected to the Public
Switched Telephone Network (PSTN).
Paved the way for computers to communicate using
the telephone switching infrastructure.
13.15.2 Evolution of the Internet
• 1965 DoD DARPA plans first computer
network
• 1969 ARPANET connects 4 computers using
packet switched network
– Stanford Research Institute, UCLA, UC Santa
Barbara, and the University of Utah
– Networking luminary Leonard Kleinrock, is
credited with successfully sending the first
network “message” from UCLA to Stanford.
13.15.2 Evolution of the Internet
• “Router” in the network was called Interface Message
Processor (IMP), built by a company called BBN (which
stands for Bolt, Beranak, and Newman Inc.).
– IMP system architecture required a careful balance of the
hardware and software that would allow it to be used as a
store-and-forward packet switch among these computers.
– IMP's used modems and leased telephone lines to connect
to one another.
• 1971 The ARPANET grows to 23 hosts connecting
universities and government research centers around
the country.
13.15.2 Evolution of the Internet
1973 Robert Metcalfe and David Boggs invent
the Ethernet networking system at the Xerox
Palo Alto Research Center.
13.15.2 Evolution of the Internet
• 1973 The ARPANET goes international
13.15.2 Evolution of the Internet
• 1975 Internet operations transferred to the
Defense Communications Agency
• 1978 Hayes Microcomputer Products releases the
first mass-market modem, transmitting at 300
bps (0.3K).
• 1980 John Shoch at Xerox creates the first
“worm” program, with the capacity to travel
through networks.
• 1981 Ungermann-Bass ships the first commercial
Ethernet network interface card.
13.15.2 Evolution of the Internet
• 1981 ARPANET has 213 hosts. A new host is
added approximately once every 20 days.
• 1982 The term 'Internet' is used for the first
time.
• 1983 TCP/IP becomes the universal language
of the Internet. Developed by Vinton Cerf and
Robert Kahn
• 1984 CISCO founded
• Early 80's Unix and IBM OS included TCP/IP
13.15.2 Evolution of the Internet
• Late 90's Internet becomes household term
– Needed PC
– Needed "Killer app" i.e. WWW & browsers
13.15.3 PC and the arrival of LAN
• 1971 Intel introduces the first microprocessor
- the Intel 4004.
• 1971 The Kenbak-1, the first microcomputer,
is introduced in Scientific American, selling a
total of 40 units in 2 years.
Used 130 IC's with a 256 byte memory and 8-bit
words, processed 1000 instructions per second, and
cost $750.
13.15.3 PC and the arrival of LAN
• 1972 Intel launches the 8-bit 8008 - the first
microprocessor which could handle both
upper and lowercase characters.
• 1972 Xerox develops the Xerox Alto - the first
computer to use a Graphic User Interface.
The Alto consists of four major parts: the graphics
display, the keyboard, the graphics mouse, and the
disk storage/processor box. Each Alto is housed in a
beautifully formed, textured beige metal cabinet that
hints at its $32,000 price tag (1979US money). With
the exception of the disk storage/processor box,
everything is designed to sit on a desk or tabletop
13.15.3 PC and the arrival of LAN
• 1973 Robert Metcalfe and David Boggs invent
the Ethernet networking system at the Xerox
Palo Alto Research Center.
13.15.3 PC and the arrival of LAN
• 1974 Intel introduces the 8080 microprocessor
– 5 times faster than the 8008.
– And the heart of the future Altair 8800.
• 1975 MITS markets the Altair 8800 - the first
mass-market microcomputer, launching the
Personal Computer Revolution.
• 1975 Bill Gates and Paul Allen form the Microsoft
company to create software for the new Altair
8800.
13.15.3 PC and the arrival of LAN
• 1976 Apple Computer is formed by Steve Jobs,
Steve Wozniak, and Ron Wayne, and launches
the Apple Computer.
• 1977 Tandy Radio Shack ships its first personal
computer - the TRS-80. It sells over 10,000
units, tripling expectations.
• 1977 Apple Computer launches the Apple II,
which sets new standards for sophisticated
personal computer systems.
13.15.3 PC and the arrival of LAN
• 1978 The C programming language is
completed at AT&T Bell Laboratories, offering
a new level of programming.
• 1978 Apple and Tandy ship PCs with 5.25"
floppy disks, replacing cassette tape as the
standard storage medium for PCs.
• 1978 Hayes Microcomputer Products releases
the first mass-market modem, transmitting at
300 bps (0.3K).
13.15.3 PC and the arrival of LAN
• 1978 Intel ships the Intel 8086 microprocessor,
with 29,000 transistors, and running at 4.77
megahertz.
• 1979 Personal Software creates VisiCalc for
the Apple II, the first electronic spreadsheet
program, selling over 100,000 copies.
• 1979 Intel develops the 8088 microprocessor,
which would later become the heart of the
IBM PC.
13.15.3 PC and the arrival of LAN
• 1979 Motorola develops the Motorola 68000
microprocessor, offering a new level of processing
power.
• 1979 Robert Metcalf founded 3COM
• 1980 Seagate Technology introduces the first
microcomputer hard disk, capable of holding 5
megabytes of data.
• 1980 Philips introduces the first optical laser disk,
with many times the storage capacity of floppy or
hard disks.
13.15.3 PC and the arrival of LAN
• 1980 Xerox creates Smalltalk - the first objectoriented programming language.
• 1981 Ungermann-Bass ships the first
commercial Ethernet network interface card.
• 1981 Xerox introduces the Xerox Star 8010,
the first commercial Graphic User Interface
computer, for $16,000-$17,000.
13.15.3 PC and the arrival of LAN
• 1981 Microsoft supplies IBM with PC-DOS
(which it would also sell as MS-DOS), the OS
that would power the IBM PC.
• 1981 IBM brings to market the IBM PC,
immediately establishing a new standard for
the world of personal computers.
13.15.4 Evolution of LAN
• Thicknet
– Coaxial cable/Vampire taps
– 10base5 (10 Mbits/sec, baseband, 500 meters)
– 1979-1985
Thick Coax Segment
500 Meter Maximum
MAU
15 pin AUI Connector
AUI Cable
(50 meter max)
Ethernet
Interface
MAU - Medium Access Unit
AUI - Attach Unit Interface
Male "N" Connector
50 ohm terminator
AMP
Thick
Coaxial
(Vampire)
Tap
13.15.4 Evolution of LAN
• Thinnet
– Coaxial cable/BNC connectors
– 10base2 (10 Mbits/sec, baseband, 200 meters)
10-Base-2 Coaxial Ethernet Cable with BNC terminations
– 1985-1993
Computer
Terminator
Terminator
BNC "T"
Connector
13.15.4 Evolution of LAN
• Fast Ethernet
– Move "ethernet" into the box
– 100baseT (T for twisted pair)
– RJ45 Connectors