Switch Core Configuration

Configuring a core switch involves setting up basic parameters, VLANs, trunking, SVIs, and inter-switch connectivity to ensure efficient and secure network operation.

Initial Access and Basic Setup

1. Connect to the Switch: Use a console cable and a terminal emulator like PuTTY or Tera Term to access the switch locally, or SSH if the switch already has an IP address configured .
2. Set Hostname: Assign a meaningful hostname for identification, e.g., Core-Switch or site-specific names like SFO-SW-01 .
3. Set Passwords: Configure an enable secret password for privileged access, console password for local access, and VTY passwords for remote SSH/Telnet access .
4. Assign Management IP: Configure an IP address on the management VLAN to allow remote administration .

VLAN and Port Configuration

1. Create VLANs: Define VLANs to segment network traffic logically. Use vlan and name commands .
2. Assign Ports: Configure access ports for end devices and trunk ports for inter-switch links. Access ports are untagged members of a VLAN, while trunk ports carry multiple VLANs using 802.1Q encapsulation .
3. Configure SVIs: Set up Switched Virtual Interfaces (SVIs) for Layer 3 routing between VLANs if the core switch supports Layer 3 functionality .

Trunking and Inter-Switch Connectivity

1. Trunk Ports: Enable trunking on uplinks to other switches using switchport mode trunk and switchport trunk encapsulation dot1q if required .
2. Redundancy: Use multiple links or port channels between core and edge switches to prevent isolation if a single link fails .
3. Layer 3 Mesh: For Layer 3 capable core switches, create a routing mesh using SVIs or routed interfaces and advertise routes via an IGP like OSPF or EIGRP .

Security and Optimization

1. Disable Unused Ports: Shut down unused interfaces to prevent unauthorized access .
2. Port Security: Limit MAC addresses per port and configure violation actions to enhance security.
3. Spanning Tree Protocol (STP): Ensure STP is configured to prevent loops in the network.
4. NetFlow or Monitoring: Optionally configure NetFlow or SNMP for traffic monitoring and network management .

Saving Configuration

After completing the configuration, save the running configuration to the startup configuration using write memory or copy running-config startup-config to ensure changes persist after a reboot . By following these steps, a core switch can be properly configured to manage VLANs, provide inter-switch connectivity, support Layer 3 routing, and maintain secure and efficient network operations.