Network Switching Overview

The Switch
  • Forward or drop frames
    • Based on the destination MAC address
  • Gather a constantly updating list of MAC address
    • Builds the list based on the source MAC address of incoming traffic
  • Maintain a loop-free environment
    • Using Spanning Tree Protocol (STP)


Learning The MACs
  • Switches examine incoming traffic
    • Makes a note of the source MAC address
  • Adds unknown MAC addresses to the MAC address table
    • Sets the output interface to the received interface
Flooding for unknown Macs
  • The switch doesn't always have a MAC address in the table
  • When in doubt, send the frame to everyone
Address Resolution Protocol
  • Determine a MAC address based on an IP address
    • You need the hardware address to communicate
  • arp -a
    • view local ARP table



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