Slide 25 of 25
Notes:
As more and more stations are added to an 802.3 LAN the traffic wil go up. Eventually, the LAN will saturate. One way out is to go to a higher speed, say from 10 Mbps to 100 Mbps. This solution requires throwing out all the 10 Mbps adaptor cards and buying new ones, which is expensive. Fortunately, a different, less drastic solution is possible: a switched 802.3 LAN. The heart of the system is a switch containing a high-speed backplane and room for typically 4 to 32 plug-in line cards, each containing one to eight connectors. Most often, each connector has a 10Base-T twisted pair connection to a single host computer.
Collisions on this on-card LAN will be detetecd and handled the same as any other collisions on a CSMA/CD network. With this, only one transmission per card is possible at any instant, but all the cards can be transmitting in paralel. With this design, each card forms its own collision domain, independent of the others.
If all the input ports are connected to hubs, rather than to individual stations, the switch just becomes an 802.3 to 802.3 bridge.
