Lesson 11

Switching Fundamentals

  • Switches operate at Layer 2 (Data Link Layer).

  • They reduce collision domains but do not separate broadcast domains (unless VLANs are used).

  • MAC address tables help switches forward frames efficiently.

Spanning Tree Protocol (STP)

  • Prevents switching loops in redundant network paths.

  • STP Port States:

    • Blocking: No data forwarded.

    • Listening: Prepares to forward.

    • Learning: Builds MAC table.

    • Forwarding: Actively sends traffic.

    • Rapid Spanning Tree Protocol (RSTP, 802.1w): Faster convergence version of STP.

    • Virtual LANs (VLANs)

      • Break up broadcast domains within a switch.

      • Each VLAN operates as its own isolated network.

      • Types of VLANs:

        • Static VLANs: Manually assigned.

        • Dynamic VLANs: Assigned by MAC address.

      VLAN Trunking & Protocols

      • VLAN Trunking Protocol (VTP): Cisco protocol that manages VLANs across switches.

      • 802.1Q: Standard for VLAN tagging.

      • Trunk Ports: Carry multiple VLANs across switches.

      • Access Ports: Connect to a single VLAN.

      • Advanced Switching Features

        • Port Mirroring (SPAN): Copies traffic for monitoring.

        • Power over Ethernet (PoE): Supplies power to network devices.

        • Link Aggregation (LACP): Combines multiple links into one logical connection.