Transcript NETS 3007/3907

Overview of TCP/IP and Internet
Lecture 1
NETS 3303/3603
Based on Jim Binkley’s material
Aims / outcomes
•
•
•
•
•
•
Background info on networks
The Internet, what is it?
Understanding layers and stacks
Intro to protocols
Intro to TCP/IP
Knowledge of standards, control bodies
Based on Jim Binkley’s material
Internet History
•
•
•
•
•
•
•
•
1957 Sputnik/USSR. US creates ARPA
62 - Paul Baran, packet-switches (missiles)
69 - DARPA starts ARPANET
71 - 15 nodes
73 - Ethernet/Bob Metcalfe Harvard Ph.D
79 - USENET/UUCP over modems (newsgroups)
82/83 - DARPA starts using TCP/IP on Arpanet
83 - BSD UNIX with TCP/IP, enet
Based on Jim Binkley’s material
History cont’d
•
•
•
•
•
•
•
84 - DNS and 10k hosts
88 - 6k/of 60k hosts visited by Morris worm
89 - IETF and IRTF under IAB
92 - 1st MBONE audio/video over Inet
93 - WWW begins to took over
94 - businesses and biz begin to take over
94 - gov. decides OSI not best idea...
Based on Jim Binkley’s material
DNS number growth
Date
1969
1984
1987
1989
1990
1992
1993
7/94
7/95
7/96
97
03
Hosts
4
1024
28174
130000
313000
727000
1313000
3212000
6.6 M
12.8M
20-30M
170M
Nets
Domains
650
2063
4526
7505
25210
?
?
45/55k
150k+
3900
9300
http://bgp.potaroo.net dns ???
21000
46000
120000
488000
>1m
Based on Jim Binkley’s material
Scalability Issues
• # ip addresses, # ip nets
– IPv6 may address this
• # dns names (variation, too many .com)
– politics as well as engineering
• # of routes in routers
– CIDR - classless internet domain routing
– IPv6 doesn’t help, process issue, not
architecture issue so much
Based on Jim Binkley’s material
World-wide data net vs
telco/voice
• world network demand - billions of packets
–
–
–
–
1996 - data=135, voice=948
1999 - data=1572, voice=1511
2000 - data=4451, voice=1766
2002 - data=27645, voice=2063
source: Insight Research Corp, and Boardwatch
Based on Jim Binkley’s material
TCP/IP Intro
• TCP/IP - Internet protocol suite, TCP and IP are
protocols in the suite, there are many more!
• open system, not proprietary, stacks from different
vendors INTEROPERATE
– Novell ipx, Apple appletalk - closed systems
• Internet - uses TCP/IP protocols
Based on Jim Binkley’s material
Protocol Layers
• protocol layers - each layer has its own
focus, associated encapsulation and
addressing
– 4 layers in TCP/IP (older)
– 7 in Open Systems Interconnection (newer)
• layer is logical idea and may in fact be
ignored in implementation
Based on Jim Binkley’s material
End systems and Intermediate
Systems
Based on Jim Binkley’s material
OSI Reference Model
Based on Jim Binkley’s material
TCP/IP Reference Model
Based on Jim Binkley’s material
Internet Protocols
Based on Jim Binkley’s material
Layers / Architecture
• data flows up/down stack
– each layer on write, adds header/addr. info. This
process is called encapsulation
– on read, data is demultiplexed - decide which
protocol above to feed it to, and decapsulate
• demux example: from link layer, packet
– could go to IP, ARP, RARP
Based on Jim Binkley’s material
Network and Transport Layers
• network layer - hides physical layer
– ip is hop by hop
• transport layer - end to end, error correction
– tcp is end to end
Based on Jim Binkley’s material
Two Big Ideas
• peer layers in stack virtually talk to each other - this is a “protocol”
– tcp talks to remote endpoint tcp
– ftp clients talks to ftp server
– ip src talks to ip dest and may talk to routers too
• network layer hides transport/apps from exact
details of physical layer
– routers glue together networks
Based on Jim Binkley’s material
Addressing / Encapsulation
• application - Domain Name System
(it.usyd.edu.au)
• tcp/udp, use ports, 16 bit unsigned ints
• ip - uses IP address, 32 bit unsigned ints
– (net, subnet, host)
• link layer, ethernet uses IEEE 48 bit MAC address
Based on Jim Binkley’s material
Encapsulation (packet goes out)
Based on Jim Binkley’s material
IP Addresses
• per interface. each i/f has
– (ip address, broadcast address, subnet mask)
• (network, subnet, host)
• written in dotted decimal in network byte order
(big-endian) 200.12.0.14 (0..255)
• 5 classes, A to E, each takes a bit at the hiorder
end
Based on Jim Binkley’s material
IP Class Address Table
Based on Jim Binkley’s material
IP Addresses cont’d
• 3 types of IP address (topographical)
– unicast
• 127.0.0.1, 201.3.4.5
– broadcast
• 255.255.255.255, 129.14.255.255, 0.0.0.0
– multicast
• 225.1.2.3
Based on Jim Binkley’s material
IP Addresses cont’d
• uniqueness must be handled by humans
• various IP authorities at this point, regional
address registries
– U.S. authority is ARIN (NA, SA, Africa), www.arin.net
– APNIC for asia, RIPE for europe
• IP (v4,v6) addresses + A.S. numbers (later)
• Domain name was from Internic: rs.internic.net,
Network Solutions (www.networksolutions.com),
ICANN (www.icann.org)
– now broken up into separate registration companies
Based on Jim Binkley’s material
whois
• whois - traditional tool for looking up
– 1. dns names
– 2. ip address info
• e.g.,
– % whois usyd.edu.au
– % whois -h whois.arin.net 131.252
• or 129.95
– web search: www.arin.net/tools/whois_help.html
– web: www.internic.net/whois.html
• go and play with these ...
Based on Jim Binkley’s material
Obtaining IP address
• Used to get it from the IANA/ICANN, but now
usually from ISP
• we need to worry about making sure that
addresses can be hierarchical
– CIDR blocks, allocated top-down from your “provider”
to you
– if you change providers, you get to renumber
– ip addresses dynamic or static
• dynamic means using DHCP
• static means manually configured
Based on Jim Binkley’s material
Transport Port numbers
• TCP/UDP unsigned 16-bits numbers
– 0..216-1 (65k)
• servers are known by “well-known” ports
– e.g., telnet 23, http 80, ftp 20, mail 25
• Inet Assigned Number Authority (IANA) assigns
them
– www.iana.org, also see www.icann.org
• on UNIX stored imperfectly in
– /etc/services
Based on Jim Binkley’s material
DNS
• primary function - map human readable names to
IP numbers
– staff.it.usyd.edu.au -> 131.252.220.13
• done entirely as application on top of UDP
• client-server model, with DNS servers in
relatively flat hierarchy
• OS deals with ip addresses, not DNS names
Based on Jim Binkley’s material
Client-Server Paradigm
• applications (and sometimes OS) organized in
application architecture paradigm called clientserver
• usually but not always message oriented
• client app talks app. protocol to remote server that
processes each message
• servers might be
– iterative (process message to conclusion) / UDP
– or concurrent (master/slave) / TCP
Based on Jim Binkley’s material
Server forms
• iterative:
do forever
wait/read client message
process message
write ACK to client
• concurrent
do forever
wait for connection
fork (spawn task)
child does i/o and exits
Based on Jim Binkley’s material
Internet what is it?
• Curse and salvation, many Points of View
• a suite of many app protocols on top of
• TCP/UDP/IP - open system, etc., etc.
– packet switched net on top of circuit/telco
• on MANY physical networks, WAN/LAN
• the World Wide Web (http/TCP)
– or chat rooms?
• a computer network that can survive atomic
attack?
– but where network security is an oxymoron?
Based on Jim Binkley’s material
Internet what is it?
• Internet - the world-wide set of nets combined
with TCP/IP
• internet - a bunch of nets tied together
• The Internet is built on TOP of the phone co’s net
and views the TELCO network as a link layer
black box (subnet model as opposed to peer
model)
Based on Jim Binkley’s material
Telco WAN technologies
• ATM/SDH (maybe) STM-1 (155), STM-4 (655)...
– STM-64 or faster available (WDM means virtual pipes)
•
•
•
•
•
•
T3 (<45Mbps), T1 (1.54Mbps)
Frame relay (shared load)
ADSL - new, cable modem, 256-T1 or so
ISDN 64/128k
analog modems (POTS) 56k/28.8k/14.4k
Gb ETHERNET is starting to make a dent at least
in MANs (1-10 gigabit)
Based on Jim Binkley’s material
Who controls it?
• Internet is world-wide - question for govt.
• control is very interesting
– governments versus Internet
– Inet said to “route around censorship”
• John Gilmore: www.eff.org
• IAB/IETF determine standards
• but industry may preemptively determine
standards (early bird ...)
– Netscape/Microsoft/Sun/Intel/Cisco
Based on Jim Binkley’s material
Standards Organisation
• ISOC - Internet Society. professional society to facilitate,
support, promote Inet
• IAB - technical oversight and coordination, falls under
ISOC
• IESG - Inet Eng. Steering Group oversees:
• IETF - meets 3 times a year, develops, argues over, and
standardizes protocols for Inet. 70-80 wgs. Organized in
areas, e.g., routing area.
• IRTF - Internet Research Task Force - long term research,
– just a few people compared to IETF
Based on Jim Binkley’s material
Standards Process
• standards called RFCs - Requests For Comment
– numbers > 4800 now
• IETF wg members write “drafts”, eventually may
become standards
• not all protocols have RFCs. not all RFCS are
actually used
• Go to IETF web site:
– http://www.rfc-editor.org/rfc-index2.html
Based on Jim Binkley’s material