Switch Management VLAN Gateway Configuration

The switch should be configured with a default gateway if it will be managed remotely from networks that are not directly connected

Note: Because, it will receive its default gateway information from a router advertisement (RA) message, the switch does not require an IPv6 default gateway

Task	IOS Commands
Enter global configuration mode.	S1# configure terminal
Configure the default gateway for the switch.	S1(config)# ip default-gateway 172.17.99.1
Return to the privileged EXEC mode.	S1(config-if)# end
Save the running config to the startup config.	S1# copy running-config startup-config

If you forget the last command your VLAN will work until the switch is turned off or looses power after that the VLAN will be gone