5. TWISTED PAIR
• Low cost
• easy to work with
• installed infrastructure
• crosstalk
• 300bps to 100Mbps
• “This modem is 56Kbps capable. However,
current regulations limit download speeds to
53Kbps,” the fine print from a typical modem
advertisement.
6. DSL
• Uses existing twisted pair
• 256Kbps to 40Mbps
• Loop length max about 18,000 ft.
• More correctly ADSL (Asymmetric Digital Subscriber
Line) with download speeds different from upload
speeds.
7. COAXIAL CABLE
• More expensive
• harder to work with
• not as extensive an existing infrastructure
• cable TV companies are changing this
• 56Kbps to 550Mbps
8. FIBER OPTICS
• Very expensive
• difficult to work with
• existing infrastructure limit to backbones
• 500Kbps to 30Gbps
9. MICROWAVE
• Not as expensive as land lines
• Limited to line of site, (towers)
• reasonable infrastructure
• Satellite bounce, increases expense
• geo-synchronous (22,000 miles)
• low earth orbit (cheaper, lower power)
• 256Kbps to 100Mbps
10. NEWER WIRELESS
• Cellular
• mobile data networks
• personal communications services (PCS)
• note: pagers & PDAs are not channels, they would be nodes on
one end of a channel
11. TRANSMISSION SPEED
• BPS, bits-per-second, the amount of information that
can be transmitted through a channel
• BAUD - a binary event, a signal change from positive
to negative or vice versa.
12. SPEED II
• At higher speeds a single signal change can transmit
more than one bit at a time, so the bit rate will
generally be higher that the baud rate.
• Transmission capacity is a function of the frequency,
higher frequency means higher capacity
13. MORE SPEED
• Bandwidth = range of frequencies that a channel can
support (difference between highest and lowest
frequency).
• Greater range means greater bandwidth.
• Greater bandwidth means greater transmission
capacity.
14. FASTER YET
• Bandwidth is like pipe diameter.
• Larger diameter pipes can transmit more water in a
given period of time.
• Personal Communication Services, PCSs, have a
greater bandwidth than fiber optics.
17. NETWORKS
• Local Area Network, LAN
• Wide Area Network, WAN
• Value Added Network, VAN
18. NETWORK TERMS
• File server
• Print server
• Gateway - connects dissimilar networks
• Bridge - connects similar networks
• Routers - connects networks & directs traffic
• Similar networks = same network
protocols
19. 20
Chapter 8
TRANSMISSION ON LANS
• Token Ring
• can talk only when you have the token
• cost more than Ethernet
• better for high volume traffic
• Ethernet
• talk whenever you want
• send again if collision
• works best with low volume traffic
20. TRANSMISSION ON WANS & VANS
• Packet Switching
• message broken into packets
• packets may take various routes
• message reassembled at destination
• allows load balancing on channels
• Frame Relay
• like packet switching, no error correction
21. THE INTERNET
• What is the Internet?
• Who owns the Internet?
• Why does the Internet exist?
22. EVOLUTION OF THE INTERNET
• 1970 ARPANET - 15 nodes
• 1972 first email
• 1982 TCP/IP becomes internet standard
• Transmission Control Protocol/Internet Protocol
• 1984 ARPANET - 1,000 nodes
• 1986 NSF-Net backbone on ARPANET
• 1987 ARPANET - 10,000 nodes
23. EVOLUTION OF THE INTERNET
• 1988 - businesses begin to connect to system for
research purposes
• 1989 ARPANET - 100,000 nodes
• 1989 link email between CompuServe and ARPANET
• 1990 ARPANET becomes the Internet
24. PUBLIC NETWORKS
COMPUSERVE
• 1969 started in Cleveland with single computer
• 1979 provided first email
• 1980 started national service
• Mid-1980s largest online service
• 1995 3 Million users
• 1997 purchased by AOL
25. PUBLIC NETWORKS
PRODIGY
• 1986 pilot in Atlanta, Hartford, San Francisco
• 1988 national service launched
• 1994 1st to offer WWW access
• 1999 Prodigy Classic discontinued (209,000 members)
26. PUBLIC NETWORKS
AOL
• 1991 AOL for DOS
• 1993 AOL for Windows
• 1997 bought CompuServe
• 1999 10 Million users
• Estimated to have distributed over 1 Billion discs of
over 1,000 different disk/CD styles
28. THE KEYS TO INTERNET GROWTH
• 1991 WAIS and Gopher provide Internet search and
navigation
• 1992 WWW hyperlink software released
• 1992 NSF relaxes its restriction on commercial Internet
traffic
• 1992+ explosive growth in usage
30. WORLD WIDE WEB
• Set of standards for storing, retrieving, formatting, and
displaying information using a client/server
architecture
• Hypertext markup Language (HTML)
• browser
• search engines
31. PUTTING IT ALL TOGETHER
AT&T Level 3
Centurylink
I29 Cable One
Consumer Consumer Consumer
32. SOME UPPER TIER PROVIDERS
• AT&T
• Bell Atlantic
• Bell South
• Cable and Wireless
• Cable One
• GTE
• IBM
• MCI
• Pacific Bell
• QUEST
• Sprint
• US West
33. TIER 1 NETWORKS
• The largest backbones on the Internet:
• Centurylink, Telecom Italia, Verizon,
Sprint, TeliaSonera International, NTT
Communications, Deutsche Telekom,
Level 3, AT&T
• These top branded backbones only trade
peering traffic among themselves.
34. COMMON BANDWIDTHS
• 56K modem 0.056 Mbps
• ADSL 40 Mbps
• Cable Modem 50 Mbps
• T1 1.5 Mbps
• Ethernet 10 to 1,000 Mbps
• T3 44.7 Mbps
• See http://bandwidthplace.com/
36. ORGANIZATION BENEFITS OF
INTERNET
• Reducing Communication Costs
• virtual private net
• Enhancing Communication and Coordination
• Accelerating the Distribution of Knowledge
• Facilitating Electronic Commerce
37. INTRANETS
• An internal network based on World Wide Web technology
• Firewall
• security software to prevent unauthorized access to an intranet
• Firebreak
• a physical break between the Internet and Intranet
39. IP ADDRESSES
• An identifier for a computer or device on a TCP/IP
network. Networks using the TCP/IP protocol route
messages based on the IP address of the destination.
The format of an IP address is a 32-bit numeric
address written as four numbers separated by periods.
Each number can be zero to 255. For example,
1.160.10.240 could be an IP address.
40. IP ADDRESS CLASSES
• Class A - 168.212.226.204
• supports 16 million hosts on each of 127 networks
• Class B - 168.212.226.204
• supports 65,000 hosts on each of 16,000 networks
• NDUS has two Class B addresses
• 134.129.xxx.xxx Eastern ND
• 134.234.xxx.xxx Western ND
• Class C - 168.212.226.204
• supports 254 hosts on each of 2 million networks
41. IPV4 VS. IPV6
• IPv4
• 32 bits used for address
• 4,294,967,296
• Addresses not assigned by geographic region (see map)
• IPv6
• 128 bits used for address
• 340,282,366,920,938,463,374,607,431,768,211,456
• That about 3.7x10^21 addresses per square inch of the earth’s surface
• Addresses will be assigned by geographic region
42. IPV4 VS. IPV6
• IPv4 addresses written as four octets (8 bits) separated
by periods.
• 134.129.67.235
• IPv6 address written as eight 4-digit (16-bit)
hexadecimal numbers separated by colons.
• 1080:0:0:0:0:800:0:417A
43. UNIFORM RESOURCE LOCATOR
• http://www.ndsu.nodak.edu/ndsu/latimer/index.html#event
s
• http:// communication protocol
• www.ndsu.nodak.edu web server hosting the page
• /ndsu/latimer/ path to the page on the host server
• index.html filename of the page
• #events anchor in the page
44. IP & DOMAIN NAME EXAMPLES
• IP: 134.129.67.85
• URL: gdc.busad.ndsu.nodak.edu
• IP: 134.129.67.235
• URL: dyn235.minard-67.ndsu.nodak.edu
45. ICANN
• Internet Corporation for Assigned Names and Numbers
• a private sector, nonprofit organization
• responsibility for IP address space allocation, protocol
parameter assignment, domain name system management
and root server system management functions previously
performed under U.S. Government contract
• ICANN's diverse board consists of nineteen Directors, nine
At-Large Directors, who serve one-year terms and will be
succeeded by At-Large Directors elected by an at-large
membership organization. None of the present interim
directors may sit on the board once the permanent
members are selected.