Physical Properties
The original 'standard' Ethernet proposal was for a 3Mbps network,
connecting up to 256 stations (1975).
The IEEE-802.3 standard has since been introduced which at first supported up to
1024 stations at 10Mbps over a total length not exceeding 2.5km.
| Type |
Cable |
Max. Segment |
Nodes/seg. |
Advantages |
| 10Base5 |
Thick coax |
500m |
100 |
Used for backbones |
| 10Base2 |
Thin coax |
185m |
30 |
Cheaper |
| 10Base-T |
Twisted pair |
100m |
1024 |
Easy maintenance |
| 10Base-FX |
Fiber optic |
2000m |
1024 |
Best between buildings |
- Each packet must be at least 64 bytes long to provide some reasonable
chance of detecting collisions over long-ish propagation times.
- Due to power losses within the Ethernet cables,
each segment cannot exceed 500m, so repeaters were used to connect
up to 5 segments in a single LAN.
- Later additions to the 802.3 standard support increasingly faster
twisted pair speeds: 100Base-T, 1000Base-T, and recently 10GBase-T.
- Similarly, fiber optic speeds and segment lengths have increased: 10GBase-ER
(extended range) allows 40km. 100Gbps is in the works.
More recently, there has been an 'explosion' in wired Ethernet categories:
- Standard: 10Base5, 10Base2, 10BaseT, 10BaseFX
- Fast: 100BaseTX, 100BaseT4, 100BaseFX
- Gigabit: 1000BaseT, 1000BaseLX
- 10-Gigabit: 10000BaseT, 10000BaseLR
CITS3002 Computer Networks, Lecture 4, Local Area Networks (LANs and WLANs), p11, 20th March 2024.
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CITS3002