Ethernet Technology

time
Collision Detection and Late Collision
A B
Start of A’s frame
Start of B’s frame
Extensions of Bus (10Base2/5) Networks
• Two segments (Cable) Ethernet (10Base5 for each segment)
500
jammed
B
C
A
End of A’s frame
• An undetected collision
Why ? A
time
Collision of
two frames
B
End of B’s frame
50
(repeater)
E
D
I
50m max
F
G
H
Collision
back
Ethernet Technology CSMA/CD
25
500
Ethernet Technology 26
Extending 10Base5 Ethernet with Repeater/Half-repeater
A
C
J
1
1
2
B
I
4
K
(max length A N = 2,500m)
(repeater)
3
G H
3
Ethernet Technology (Reference: N.-F. Huang, LAN and HSN)
27
D
F
, half repeater
1000
4
2
N
5
5
6
E
500m, max
L
M
Slot time (Collision window) calculation
0.1us 0.1us 5 5 2.0us
5.13ns/ 0 300 300 3.08us
0.05us 0.3us 3 3 2.10us
0.05us 0.6us 3 0 1.95us
0 0.9us 0 3 2.70us
4.33ns/ 0 1500 1500 12.99us
5.13ns/ 0 1000 1000 10.26us
0.1us 0 2 2 0.40us
0.1us 0 2 2 0.40us
0.2us 0.4us 2 0 1.20us
0.2us 0.2us 0 2 0.80us
0 0.2us 5 0 1.00us
0 0.2us 0 5 1.00us
0 0.1us 3 0 0.30us
70% 500
50% 0 2.0us 0 3 6.00us
94% 500
0 0.2us 0 1 0.20us
51.2uS
46.38us
Ethernet Technology 28