I would need suggestions from anyone who could help me here to understand if my understanding here is correct and if there's anything that could be added. The switch needs to work twice rather than just forward a frame.
In scenario 2 it has to first search for the destination unicast mac in its own table and then because its not available it has to broadcast it (the actual data packets forwarded by the router not the arp requests) out of all ports. To bring the port up you would need to shutdown no shutdown on the interface. The only difference that I feel could be the reason behind having the arp timer configured less than the mac-aging timer is that In Scenario 1 the switch has to just forward the frame out all ports becasue of the broadcast address in the frame without having to take a decision of its own. Ping, aging time will remove the address from being learned, but it will not bring the port out of errdisable.
In both these scenarios the Switch has to broadcast the frame out all ports when one of the two timers expire. The switch since it does not have any entry for the destination mac has to broadcast the packet out of all ports (unicast flooding). The 元 device( router) however still has the arp entry for the IP and forwards a frame to the Destination mac of the PC. Scenario 1 : Arp timeout Mac-aging timerĬonsider a situation where the ARP timeout on the 元 device is set to 1200 secs ( 20 mins) and that on the L2 switch is 900 secs (15 mins).ĩ00 secs after learning a MAC the L2 switch looses its mac entry becasue of the mac-aging timer. ma4000(config) mac address-table aging-time 400. I've tried to apply some thought to it and this is what I could muster up. Step2 switch(config)mac-address-table aging-time seconds Theseconds rangeisfrom0to1000000.Thedefaultis 1800seconds.Enteringthevalue0disablestheMACaging. I've recently read in Ciso documents that the arp timeout should be confugured less than the mac-ding timer.