Configuration of Core Switch for Leased Line Access

Configuring a core switch for leased line access involves setting up VLANs, trunk ports, IP addressing, QoS, and redundancy to ensure reliable and prioritized traffic flow.Core Switch Role and ConsiderationsA core switch serves as the backbone of the network, connecting distribution and access layers while handling high volumes of traffic. Key considerations include Quality of Service (QoS) to prioritize critical traffic, redundancy with dual power supplies and HA configurations, and compliance with Ethernet protocols for seamless integration with access and distribution switches .Basic Configuration StepsAccess the Switch CLI: Connect via console or SSH and enter privileged EXEC mode using enable .Set Hostname and Passwords: Assign a hostname and configure enable secret for privileged access. Secure console and VTY lines with passwords or AAA authentication .Assign Management IP: Configure an IP address on a VLAN interface for management and set the default gateway:CodeCopyinterface vlan 1ip address 10.1.1.1 255.255.255.0no shutdownip default-gateway 10.1.1.254 This allows remote management and monitoring .VLAN and Trunk ConfigurationCreate VLANs for different traffic types (e.g., data, voice, leased line):CodeCopyvlan 10name Datavlan 20name Voicevlan 30name LeasedLine Assign trunk ports to connect to distribution or access switches, allowing multiple VLANs to traverse a single link:CodeCopyinterface gigabitEthernet 1/1switchport mode trunkswitchport trunk allowed vlan 10,20,30no shutdown Access ports for end devices should be assigned to the appropriate VLAN:CodeCopyinterface gigabitEthernet 1/2switchport mode accessswitchport access vlan 10no shutdown Leased Line IntegrationConfigure a dedicated VLAN or SVI for the leased line to separate traffic from internal LANs.Apply QoS policies to prioritize leased line traffic, ensuring minimal latency and packet loss for critical applications .If connecting multiple core switches, consider HSRP or VRRP for gateway redundancy.Security and RedundancyEnable port security and ACLs to restrict unauthorized access.Use link aggregation (EtherChannel) for redundancy and higher bandwidth between core and distribution switches .Monitor switch health and logs to detect failures early.VerificationUse commands like show vlan brief, show ip interface brief, and show spanning-tree to verify VLANs, IPs, and trunk status.Test connectivity over the leased line using ping and traceroute to ensure proper routing and QoS enforcement. By following these steps, the core switch will be properly configured to handle leased line access, maintain high availability, and prioritize critical traffic efficiently.