Transcript Session 2B

Internet and Intranet
Fundamentals
Class 2
Session B
Topics
• The Internet Part I
– History
– TCP / IP Protocol Suite
Internet History
• Some resources
– The Internet Society
• http://www.isoc.org/internet-history/brief.html
– BBN Timeline
• http://www.bbn.com/timeline/
Internet History
• Late 1950s: ARPA Founded
– (Advanced Research Projects Agency)
– J.C.R. Licklider first director of Information
Processing Techniques Office (IPTO)
• Early 1960s: Packet Switching Concepts
Outlined
– Leonard Kleinrock (UCLA)
– Paul Baran, et. al.
– Rand Corp.
Internet
Packet Switching Theory
• First Paper
– L. Kleinrock, "Information Flow in Large
Communication Nets", RLE Quarterly Progress
Report, July 1961.
• First Book
– L. Kleinrock, Communication Nets: Stochastic
Message Flow and Delay, Mcgraw-Hill (New
York), 1964.
Internet History
• 1965: ARPA Study “A Cooperative
Network of Time-Sharing Computers”
• 1967: Larry Roberts begins developing
Rand concepts at ARPA
• 1967: Packet Switch concept developed -Interface Message Processor (IMP)
• 1968: ARPA lets RFQ for 4 IMPs
Internet History
• 1969: ARPANET is born
– 4 IMPs
– UCLA, SRI, UCSB, U. of Utah
• 1969: Network Working Group (NWG)
formed to develop protocols
• 1970: Network Control Protocol (NCP)
created
– precursor to TCP
Internet History
• 1971: Telnet and FTP defined by NWG
• 1971: ARPANET grows to nearly 2 dozen
sites
• 1972: Public demonstration of ARPANET
• 1972: First e-mail sent
– Ray Tomlinson, Larry Roberts
• 1973: First international ARPANET
connections
Internet History
• 1975: Transmission Control Protocol (TCP)
defined
– NCP not reliable
– Robert Kahn (requirements)
– Vinton Cerf (detailed design)
• 1975: 63 Nodes
– addressing revised
– Telnet revised
Internet History
• 1976: First Internet routers
• 1976: CCITT defines X.25
– Comite Consultatif Internationale de
Telegraphique et Telephonique
– X.25 = Packet Switching
• 1976: Bell Labs develops UUCP
– Unix-to-Unix copy
• 1979: USENET established
Internet History
• 1980: 400 hosts, 10,000 users
• 1981: Change from NCP to TCP/IP
mandated
– must go into effect by Jan 1, 1983
• 1982: DoD builds Defense Data Network
based on TCP/IP
• 1983: ARPANET splits into ARPANET and
MILNET
Internet History
• 1983: TCP/IP established
• 1983: Nameservers established
• 1983: Desktop workstations introduced and
LAN technologies take off
• 1985: DNS established
• 1985: >1,000 hosts
• 1986: NSFNET founded
Internet History
• 1987: 4,000 hobbyist bulletin boards
• 1988: ARPANET exceeds 77 million
packets / day
• 1988: ARPANET dismantling begins
• 1989: ARPANET ceases to exist
– now called Internet
– 100,000 hosts
Internet History
• 1991: Archie, gopher, WAIS
• 1991: Commercial Internet Exchange
founded to handle commercial use of
Internet
• 1992: 17,000 networks in 33 countries
– over 1 million hosts
• 1993: WWW
• 1993: InterNIC created
Internet History
• 1993: 1.5 million hosts in over 100
coutnries
• 1994: US lawmakers consider National
Information Infrastructure
• 1994: Commercial users outnumber
academic 2-to-1
• July 1994: 3,000,000 hosts
Internet History
• April 1995: Commercial online providers
(Compuserve, AOL, Prodigy) offer access
to Internet
• July 1995: 20-30 million users estimated
• Nov 1995: Commercial sites index:
>15,000
• Nov 1995: Java, JavaScript, VRML
Topics
• Internet Protocols
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TCP/IP Overview
Layers
IP Addressing
TCP
UDP
DNS
Internet Protocls
TCP/IP Overview
• TCP / IP = Transmission Control Protocol /
Internet Protocol
• Early 1970s
– ARPANET
• Distributed with UC Berkeley UNIX in
Early 1980s
• Public Domain, Non-Proprietary, Open
Source
Internet Protocols
Layers
• Four Layer Model
– Application
– Transport (TCP / UDP)
• contains some Session features
– Network (IP)
• actually there are three sublayers
– internet (IP)
– convergence
– subnet
– Data Link and Physical
Internet Protocols
Layers
• Packet Switching
– datagrams
• Nodes
– hosts
• end-user machines
• clients or servers
– routers
• connecting different networks
• a router is also a host of sorts
Internet Protocols
Layers
• Connection-Oriented
– TCP
– reliable two-way, byte stream protocol
• Connectionless
– UDP = User Datagram Protocol
• also known as the “Unreliable Datagram Protocol”
Internet Protocols
Layers
Layer
Application
Transport
Protocls
Telnet FTP
(login) (files)
TCP
SMTP
(mail)
Internet
Network
Datalink
Physical
DNS
(names)
NTP
(time)
UDP
NFS
(files)
IP
Ethernet
ISO 8802-2
IEEE
802.3
X.25
IEEE
802.5
Various
SLIP
PPP
Internet Protocols
IP Addressing
• Four Bytes Wide
• Dotted Decimal Notation
– 128.34.239.56
– high order to low order
• or MSB to LSB
• Network Number
– can be 1, 2, or 3 bytes long
• Host Number
Internet Protocols
IP Address Classses
Class
High Order Bits of
First Byte
0123
Network Range
Low
Host Range
High
Low
High
A
0 ---
0.0.0.0
127.0.0.0
0.0.0
255.255.255
B
10--
128.0.0.0
191.255.0.0
0.0
255.255
C
110-
192.0.0.0
223.255.255.0
0
255
D
111-
224.0.0.0
239.255.255.255 N/A
N/A
E
1111
240.0.0.0
255.255.255.255 N/A
N/A
Internet Protocols
IP Addressing
• Reserved Addresses
– all bits 0 on network number => this network
– all bits 0 on host number => this host
(localhost)
– multicasting (broadcast) class D
– class E reserved
• Subnet Masking
– portion of host number used to identify the
subnet
Internet Protocols
TCP
• Reliable, Bidirectional Byte Stream
– like a UNIX pipe
• End-to-End Reliability
• Bandwidth Optimization (flow control)
• Ports
– source
– destination
Internet Protocols
UDP
• User Datagram Protocol
• Ports (like TCP)
• Length, Checksum, Data
– no sequencing or acknowledgment structure
– error handling left to applications protocol
• DNS uses UDP
Internet Protocols
DNS
• Domain Name System
• Distributed
– database scattered across thousands of
nameservers
• Top-Level Domains
– root domain: .
– net, edu, com, org, mil, and country codes (jp)
• FQDN: Fully Qualified Domain Name
DNS Naming Tree
.
com
edu
ucr
org
utexas
cs
im4u
ee
gonzo
jp
Internet Protocols
DNS
• Address Records (A records)
– translates domain names to IP addresses
• Mail Related Resource Records
– MX Records
• Caching
– local nameservers can cache name-to-address
translations for a period controlled by the
authoritative nameserver
DNS Architecture
query or reply
to/from another server
Server
query or reply
query
reply
Resolver Library
function
call
function
return
Application
IPv6
Chief Characteristics
• Replaces IPv4
– current IP
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Expands 32 bit addressing to 128 bit
Autoconfiguration
QOS Features
Reduced Overhead
Authentication/Privacy Provisions
IPv6
Development History
• Mid 90s Scare re Address Space
– seem to be running out
– IPv4 has been updated to avoid this problem
• IETF = Internet Engineering Task Force
– recommended IPng (informal name) July 94
– RFC 1752
IPv6
Design Goals
• Evolutionary Step
– smooth transition from IPv4
– no disruption
– peaceful coexistence
• Plan for Future Applications
– high bandwidth
IPv6
PDU
• 4-bit Priority Field
• 24-bit Flow Label
– QOS
• 16-bit Payload Length
• 8-bit Next Header (same as IPv4)
– identifies header immediately following IPv6
header
• 8-bit Hop Limit
• 128-bit Source and Destination Addresses
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| Prior |
Flow Label
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Payload Length
| Next Header | Hop Limit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Source Address
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Destination Address
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IPv6
Extension Headers
• Next Header Field
– identifies type of optional extension header
after IPv6 header
• Extension Header Sandwiched between
IPv6 and Transport Layer Protocol
• Most Not Examined or Processed by
Intermediate Routers
– faster forwarding
• Arbitrary Length
IPv6
Addressing
• Ample Address Space
– 2^^96 times that of IPv4 (2^^32)
– 340,282,366,920,938,463,463,374,607,431,768,211,456
– 665,570,793,348,866,943,898,599 addresses
per square meter of Earth surface
• ignoring routing hierarchy
– more pessimistic estimate: 1,564 addresses per
square meter of Earth surface
• Keep in Mind Device Control Apps
IPv6
Addressing
• Unicast Hierarchy
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Registry
Provider
Subscriber
Subnet
Interface
IPv6
Addressing
• Anycast
– packets routed to “nearest” interface with that
address
• Multicast
– Scope Limiting Field
• limits number of hosts to which packet is broadcast
IPv6
Security Features
• IPv6 Authentication Header
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authentication
integrity
but not confidentiality
addresses spoofing problem
• IPv6 Encapsulating Security Header
– integrity
– confidentiality
IPv6
QOS Capabilities
• Flow Label and Priority Fields
• Flow
– sequence of packets from source to destination
– requiring special handling by intervening
routers
• Real-Time Service
• Priority
– source congestion control (backs off) vs.
– non-back off
IPv6
Other Improvements
• Expanded Packet Length
– IPv4: 64KB packet length
– IPv6: 4GB
• “Jumbograms”
• Autoconfiguration
– allows a node to discover its own address upon
booting
• 6bone: experimental backbone for IPv6
IPv6
Summary
• Good Idea
– but no longer urgent
• Will Probably Evolve