switching

## What I do - Configure and manage network switches - Implement VLANs and trunking - Configure spanning tree protocols - Set up switch stacking and stacking - Manage VLAN routing (SVI) - Implement port security - Configure switch monitoring ## When to use me Use me when: - Designing local area networks - Configuring access/aggregation switches - Implementing network segmentation - Troubleshooting connectivity issues - Setting up switch infrastructure ## Key Concepts ### Layer 2 Switching Switches operate at Layer 2, forwarding based on MAC addresses: ``` ┌─────────────────────────────────────┐ │ Switch Forwarding │ ├─────────────────────────────────────┤ │ MAC Address Table (CAM Table) │ │ Port 1: aa:bb:cc:dd:ee:ff │ │ Port 2: 11:22:33:44:55:66 │ │ Port 3: aa:bb:cc:dd:ee:11 │ └─────────────────────────────────────┘ Frames forwarded based on: - Destination MAC known → Forward to port - Unknown → Flood to all ports - Broadcast → Flood to all ports ``` ### VLAN Configuration ```cisco ! Create VLANs vlan 10 name Data vlan 20 name Voice vlan 99 name Management ! Assign ports to VLANs interface GigabitEthernet0/1 switchport mode access switchport access vlan 10 spanning-tree portfast ! Trunk port interface GigabitEthernet0/24 switchport trunk encapsulation dot1q switchport mode trunk switchport trunk allowed vlan 10,20,99 ``` ### Spanning Tree Protocol - **STP**: 802.1D, 50-second convergence - **RSTP**: 802.1w, rapid convergence - **MSTP**: 802.1s, multiple spanning trees - **PVST+**: Per-VLAN STP (Cisco) ### Switch Features - Port Security: Limit MAC addresses - DHCP Snooping: Prevent rogue servers - ARP Inspection: Prevent ARP spoofing - Storm Control: Broadcast suppression - QoS: Traffic prioritization