Solution: Increase the MAC age time on switch. ARP requests will be processed less frequently by the switch.
Nexus 5K/7K: ARP Default Timeout 1500 Seconds 25 Minutes. switchshowmac-address-tableaging-time Vlan AgingTime-1 300 13 300 42 300 Cisco Nexus 3000 Series NX-OS Layer 2 Switching Configuration Guide, Release 5. On the 6500’s it’s 4 Hours and on the Cisco Nexus it’s 25 Minutes. The default timeout period will be 360 seconds. If you migrate from a Cisco 6500 to a Cisco Nexus switch, keep in mind that the ARP Default Timeout is very different. Cisco-SW(config)mac address-table aging-time 0-0> Enter 0 to disable aging 10-1000000> Aging time in seconds Cisco-SW(config)mac address-table aging-time 500 routed-mac Set RM Aging interval vlan VLAN Keyword cr If you want to configure static MAC address on a Cisco switch, then below are the command. The MAC address-table will be flushed every 3 minutes. This is how long a dynamic MAC address will remain in the CAM table. As soon as the switch receives the next packet from a device off the port, the MAC address is added back to the table and updated in Network Sentry. What effect does the mac address-table aging-time 180 command have on the MAC addresstable A. If MAC Notifications are enabled, a MAC Removed trap would be sent every time the addresses are flushed, thus the port in the port view is updated to show an empty port. Command in Cisco switch looks similar to the following example (set to 15 seconds): If the MAC address aging time is set on the switch or VLAN to a low interval (such as 15 seconds), the mac address(es) will be removed from the switch's MAC address table every 15 seconds. Does that mean, even if there is a MAC address in the CAM table for a destination MAC address, the switch will still broadcast the frame out. My book says that when the MAC address table becomes fully, the switch goes into fail-open mode and broadcasts ALL frames to all ports except the ingress port.
The switch itself, however, does not report the link state changing in its CLI. Hello, Would someone be able to clarify a point regarding MAC address table overflow attacks.
To return to the default settings, use the no form of this command. Network switching fundamentals are required for CCNP Enterprise Core studies. Operational Status changing from Linkup/link down every several second. To configure the aging time for entries in the Layer 2 table, use the mac address-table aging-time command.All MAC addresses on a port disappear at once after several seconds, then return.Issue: Topology Port View shows the following behavior on various ports on the Cisco switch: