Configure default routing for core switches

Use ip default-gateway for Layer 2 switches and ip route 0.0.0.0 0.0.0.0 for Layer 3 switches to configure default routing.Layer 2 SwitchesFor switches operating purely at Layer 2 (L2), IP routing is not enabled, so the switch cannot forward packets based on IP addresses. In this case, you configure a default gateway to allow the switch to communicate with devices outside its local subnet, primarily for management purposes such as SSH, Telnet, SNMP, or syslog:CodeCopySwitch(config)# ip default-gateway This command sets the default gateway for the switch's management VLAN.If no default gateway is configured, the switch may rely on proxy ARP from a router on the same subnet to reach remote management hosts.This configuration does not affect user traffic that is switched at Layer 2 .Layer 3 SwitchesFor Layer 3 (L3) core switches, IP routing must be enabled to forward traffic between VLANs or to external networks. In this case, the default gateway is ignored, and you must configure a default static route:CodeCopySwitch(config)# ip routingSwitch(config)# ip route 0.0.0.0 0.0.0.0 ip routing enables Layer 3 routing on the switch.ip route 0.0.0.0 0.0.0.0 directs all traffic destined for unknown networks to the specified next-hop router.This default route is used for all traffic not explicitly matched in the routing table, ensuring connectivity to external networks or the internet .Best PracticesManagement VLAN: Assign a dedicated VLAN for switch management and configure the default gateway or default route on that VLAN interface.Redundancy: For high-availability networks, consider configuring floating static routes or using dynamic routing protocols alongside default routes to provide failover paths.Verification: Use commands like show ip route and ping to verify that the default route is correctly installed and reachable.Security: Limit management access to trusted subnets and use ACLs to protect the switch management interface. By following these steps, core switches can properly forward unknown traffic while maintaining secure and manageable network operations .