Networking vs. Timesharing

1
Networking vs. Timesharing
Mainframe OS 370
PC, Win98
Mac OS X 10.1
Server, Unix
Protocol
PC, Win2000
Terminals, Consoles
2
Local Area Network Emerged, 1970s
Chicago
Boston
Seattle
NYC
Denver
SF
LA
Houston
3
Local Area Network (LAN)

• Range The same building, same floor, same
  lab, same department. Within about 50 Ms.
• Computers Micro Computers, Workstations
  usually, but not necessarily, the same platform.
  
• Purposes Sharing resources, e.g., printers,
  files, (Internet access), programs, internal
  email exchange.

PC, Win98
Mac OS X 10.1
Server, Unix
Protocol
PC, Win2000
4
Topology of LAN
The way in which the computers connected.
Bus Topology
Ring Topology
Star Topology
Direct Topology
5
IBM Token Ring
Free Token
Busy Token
There is only one token circulating in the ring,
and the computer that has the token gets the
access to the cable.
To From Data
3 5 ooo
1
4 2 100
5
4 2 100
3 4 ABCD
4 ? 2
2
3 ? 4
4

• These processes can be done by hardware.
• Conventions format, the size of a token, the
  speed of the token.
• How to prevent starvation?

2 ? 3
3
6
Ethernet

• IEEE 802.3 Standard
• CSMA/CD
• Carrier Sense Multiple Access/ Collision
  Detection

5
1
3
jar
100 Mb/sec
4
2
A packet 128 bytes, 1024 bits
1 - - - - - - - - -
2 - - - - - -
- - -
0 1 2 3 4 5 6 7 (ms, 10-3 sec)
Listen and send
Collision
7
Wide Area Network , early 80s
Chicago
Boston
CNY
Seattle
NYC
Denver
SF
LA
Houston
8
WAN ? Backbone Network
Chicago
Boston
CNY
Seattle
NYC
Denver
SF
ARPANET CSNET NSFNET ANSNET
LA
LA
Houston