1. Ethernet The most popular LAN technology Open Standard
Open and wide market

2. Ethernet
1970: Xerox in PARC, Robert M. Metcalfe, David Boggs, Charles Thacker, Butler Lampson
Experimental Ethernet, 3Mbps
1979: Formal specifications DIX (DEC- Intel-Xerox). 10Mbps
1985: “IEEE CSMA/CD” is published
It has included new technologies periodically

4. Operation Stations connected to a SHARED MEDIUM No main controller
Serial transmission to the medium, Manchester
CSMA/CD
Colissions

5. Shared
Medium

6. BUS

7. Transmission in the BUS

8. Colission

9. Persistence and Non persistence9

10. CSMA/CD Station ready for transmission Sense the Wait a random channel
time (BEB)‏
Busy
Free
Transmit
listening
Stop transmission
and
Start jam signal
Collision
End of
transmission

11. MTU Maximum Transfer Unit Big frames are not good for multiplexing
Big delays in “conversations”
More collisions

12. Importance of 2tp
~ 2tp tp
~ tp
Lmin(t) = 2tp