MAC show fdb listing wrong port for a PC
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‎08-08-2016 06:51 PM
I was looking for a device on a x460 switch by mac. I ran sh fdb . The return listed the machine's mac on our gateway port. I found the correct port by using the phone's mac which showed the correct port that the device was connected. The machine had no physical connection to the gateway port !!!! Anyone have any ideas how this could happen. The device port was a netlogin configured port.
9 REPLIES 9
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‎08-11-2016 08:38 AM
Most likely switch recieved packet on port 4:4 with SMAC *:13:d2:dd. Do you always see the issue or it happened once? What happenes when FDB entry ages out?
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‎08-11-2016 08:38 AM
The examples show no learning. Are there other reference showing the MAC being associated with another port?
* Slot-1 switch37 # sh fdb port 4:4
Mac Vlan Age Flags Port / Virtual Port List
------------------------------------------------------------------------------
*:00:3f:cd Default(0001) 0044 d m 4:4
*:47:ed:61 Default(0001) 0044 d m 4:4
*****:13:d2:dd Default(0001) 0104 d m 4:4 this shouldn't be here
*:60:38:51 Default(0001) 0044 d m 4:4
* Slot-1 switch37 # sh fdb port 4:4
Mac Vlan Age Flags Port / Virtual Port List
------------------------------------------------------------------------------
*:00:3f:cd Default(0001) 0044 d m 4:4
*:47:ed:61 Default(0001) 0044 d m 4:4
*****:13:d2:dd Default(0001) 0104 d m 4:4 this shouldn't be here
*:60:38:51 Default(0001) 0044 d m 4:4
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‎08-10-2016 06:02 AM
I have seen the behavior outlined in the following knowledge base article in https://gtacknowledge.extremenetworks.com/articles/Solution/CDP-packets-may-cause-packet-loss-in-con...
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‎08-09-2016 04:11 PM
The gateway port connects to Cisco routers. How can CDP affect a locally connected mac table entry?
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‎08-09-2016 02:07 PM
A topology diagram showing your network layout particular is there are any redundant links would help better answer your question. Also, do you have CDP enabled devices communicating through the switch or sending CDP packets to the switch?
