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CCNP Routing and Switching Quick Reference Library: ROUTE 300-101, SWITCH 300-115, and TSHOOT 300-135 Quick References by Brent Stewart, Denise Donohue

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Chapter 1. LAN Switching Basics

Switches were developed from hubs, by way of bridges. In a hub, all ports share access to the backplane so that if multiple ports forward data at the same time, a collision occurs. The Carrier Sense Multiple Access with Collision Detection (CSMA/CD) process attempts to correct for this by detecting a collision and backing off before resending the data. Ports on hubs operate at half-duplex mode; they can either send or receive but cannot do both at the same time. The entire hub is said to be in one collision domain.

On a switch, each port is its own collision domain. Traffic is not forwarded to all ports, only to the port where the destination device is located. Switch ports can operate in full-duplex mode, sending ...

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