MAC Addresses from Edge Switch Not Showing on Upstream Switches

[bud.sweeney]

I have a ws-c2960x-48fpd-l switch dual connected to a stacked ws-c3850-12xs configuration. The stacked 3850's are connected to a collapsed Core 4507. My issue is that some of the devices hanging off the 2960 will show the MAC address on the 2960 switch, but will not show the MAC address on the upstream stacked 3850. In other cases, it will show the MAC address on the stacked 3850, but will not appear on the Core 4507.

I have confirmed that all VLANs are configured on the switches end-to-end and the VLANs are configured on the trunk ports. Port security is enabled on the 2960 access ports allowing 1 MAC address. 

Any suggestions on where to look why the MAC is not flowing from switch to switch would be greatly appreciated.  It most likely is some thing simple that I am overlooking. I can provide outputs if needed.

Thanks,

[pigallo]

Hi,

first thing i want to ask is if you`ve check out for static mac addresses in your CAM table before think that mac addresses do not flow between switches.

Second thing i want to ask is if you verified for topology changes on the ports you were testing because topology changes flush cam table once generated.

Third thing i want ask is if the hosts were active on the links, so they were actively sending/receving data on the ports.

Fourth thing i want to ask is if you verified the cam under particular vlan and not for a specific mac address for searching host mac addresses, like show mac address-table vlan xyz | sec aaaa.bbbb.cccc

Fifth thing is to verify if behind the port there are VMs attached. In that case you won`t see the hardware mac of the device/server connected to the port, since what really generates traffic is the VM. So in that case you will be able to see only the VM mac addresses, not the host macs.

Also, sixth thing to check is if the cam aging-timers are aligned between switches to avoid the case where one mac entry that doesn`t generate any traffic expires earlier on some switches than on other switches.

Seventh thing to verify is which kind of hosts are attached to the switches??

If the hosts are not pc but for example cameras that multicast video on a particular vlan, then in some cases i noticed that they do not show up any layer 2 information on the specific port. So one way to obtain L2 mac from it is ping the management ip address from a SVI you created on the switch. Or from another client that is connected to the switchport.