Switch function
- 1. Configuring Catalyst Switch Operations Introducing Basic Layer 2 Switching and Bridging Functions
- 2. Outline • Overview • Functions of Ethernet Switches and Bridges • Frame Transmission Modes • How Switches and Bridges Learn Source MAC Addresses • How Switches and Bridges Forward and Filter Frames • Summary
- 3. Ethernet Switches and Bridges • Address learning • Forwarding based on the learned addresses • Loop avoidance
- 4. Transmitting Frames Cut-Through Store and Forward • Switch checks destination • Complete frame is received and address and immediately checked before forwarding begins forwarding frame Fragment-Free • Switch checks the first 64 bytes, then immediately begins forwarding frame
- 5. MAC Address Table • The initial MAC address table is empty.
- 6. Learning Addresses • Station A sends a frame to station C. • The switch caches the MAC address of station A to port E0 by learning the source address of data frames. • The frame from station A to station C is flooded out to all ports except port E0 (unknown unicasts are flooded).
- 7. Learning Addresses (Cont.) • Station D sends a frame to station C. • The switch caches the MAC address of station D to port E3 by learning the source address of data frames. • The frame from station D to station C is flooded out to all ports except port E3 (unknown unicasts are flooded).
- 8. Filtering Frames • Station A sends a frame to station C. • The destination is known; the frame is not flooded.
- 9. Filtering Frames (Cont.) • Station A sends a frame to station B. • The switch has the address for station B in the MAC address table.
- 10. Broadcast and Multicast Frames • Station D sends a broadcast or multicast frame.