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icnd1:basic_switch_logic

Basic Switch Logic

The primary role of a switch is to get frames from point A to B on a LAN. It does this by examining Source and Destination MAC addresses. Not unlike a router which instead uses IP addresses.

EXPAND ON THE FOLLOWING:


SWITCH FUNCTIONS

  • Forward or Filter frames based on MAC address
  • Learn and fill MAC / CAM table based on incoming MAC address
  • Prevent Layer 2 loops with STP

SWITCH FORWARDING LOGIC

  • Switch receives / examines frame
  • Is the frame's source MAC in the table?
    • NO: Add source MAC to table with associated port #
  • Is the frame's destination MAC in the table?
    • NO: Flood frame out all ports in same VLAN except the port it originated from.
    • YES: Forward frame out appropriate port.
  • If destination MAC is unknown | broadcast | multicast
    • Flood frame out all ports in the same VLAN except the port it originated from.
FILTERING

AKA, not sending the packet out X interface. Port Security is a good example of this.

icnd1/basic_switch_logic.txt · Last modified: 2015/12/13 00:23 (external edit)