Then it doesn't Switch1#sh mac address-table | inc Gi2/1/3 The mac address shows up when I search for it again Switch1#sh mac address-table | inc f0b2 The mac address shows up in the table now Switch1#sh mac address-table | inc f0b2 During troubleshooting, it may be helpful to investigate the entries in the MAC table. Switches maintain a database of MAC addresses, both manually configured (static) and dynamically learned entries. The mac address doesn't show up suddenly Switch1#sh mac address-table | inc Gi2/1/3 View the MAC Address Table on a Cisco Switch. The mac address shows up when I search for it Switch1#sh mac address-table | inc f0b2 = Switch1#sh mac address-table | inc f0b2 Confirming which port is trunked back to Switch1 If you convert the rest of the numbers in the bad MAC address you will see it is simply the bad IP address backwards (in HEX). You will see that is the last number in the actual IP address. The switch stores the learned MAC addresses in a table that is known as the CAM table. Hardware is Gigabit Ethernet, address is 0b2 (bia 0b2) E.g., first bad address the first two digits of the MAC address is 27. To make accurate forwarding and filtering decisions, the switch learns and stores the MAC addresses of all connected devices. The command show mac-address address results in a nice easy to read.

GigabitEthernet1/2 is up, line protocol is up (connected) Finding a host in a CE (Classic Ethernet) switched datacenter is a simple matter of showing the MAC address table on a switch and following the port that MAC is seen on until you end up at an access layer switch the host you are looking for is connected to. Port Vlans in spanning tree forwarding state and not pruned When the MAC address table is full, the switch floods all ports with incoming traffic because it cannot find the port number for a particular MAC address in the MAC address table. Gi1/2 1-2,30,40,42,50,60,70,72,80,82,99-100,102,254 The network intruder uses the attack tool to flood the switch with a large number of invalid source MAC addresses until the MAC address table fills up. Port Vlans allowed and active in management domain Port Mode Encapsulation Status Native vlan In the output below Switch1 is the core switch stack and Switch4 is the switch I'm investigating. When tracing the trunk port back through the network I run into the odd issue of the MAC address of the 3560's trunk port disappearing from the MAC address table in the core switch. I'm trying to rule out the connection between the switch they're plugged into (3560) and the core switch (a stack of 3570s).Д¬urrently the 3560 has one fiber connection trunked back to core switch. Only ports which have a device connected and active will show the mac address detail.I have users complaining of slowness on their machines but we can't find anything specific (ping tests, etc). With the above command, one can figure out which Mac address is on which port of catalyst switch. Switch# show mac-address-table | include 0009.aabb.06e9 Or if you know the mac address and want to know which port the mac address is coming from, use the following command Switch# show mac-address-table | include Fa0/5 If you know the switch port you can use the following command Only ports which have the device connected and active will show the mac address detail. I'm trying to rule out the connection between the switch they're plugged into (3560) an. Conditions: There is no specific condition. However it is dropping only when the frame is destined to the configured mac address and it is not dropping when the frame is sourced from that particular mac address.

mac address of the connected device) and port number. I have users complaining of slowness on their machines but we can't find anything specific (ping tests, etc). Symptom: The command 'mac address-table static vlan drop' should drop the frames in both the direction.

The mac address or CAM table shows the Vlan associated with the port, MAC being learned on the port (i.e. With the command, you can figure out which MAC address is on which port. Total Mac Addresses for this criterion: 5

Cisco mac address table filling up