exec-timeout command. By default, an IOS device will disconnect a console or VTY user after 10 minutes of inactivity. You can specify a different inactivity timer using the exec-timeout MINUTES SECONDS line mode command. For example, to disconnect a console user after 90 seconds of inactivity, we can use the following command: R1 (config)#line .... But you need to maintain a balance between removing old invalid entries and keeping the amount of ARP traffic down. By default, Cisco routers use an ARP cache timeout period of four hours. This means that if the router hasn't sent or received any packets with a particular address for the last four hours, it will flush the ARP entry from its cache. "/>Nexus arp timeout