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New Member

3750 MAC table missing for one VLAN

I have one VLAN on a 3750 where I do not see any MAC addresses even though it is in use.  This is an unrouted VLAN between a WLC on a port-channel/LAG and an access port to an ASA for guest traffic.  When I do a show MAC add I get nothing for VLAN 60 (guest DMZ) but all other VLANs seem to be OK. Spanning tree is not showing TC counters incrementing either. 

I also was told when put a port on this VLAN the laptop did not get a DHCP address form the ASA, but the wireless guest clients are working fine.  I can see the DHCP leases and ARP entries in the ASA and the ASA ARP in the WLC so some traffic is passing fine.  I'm not onsite right now so troubleshooting is all remote which limits some options.

Any ideas on why there would be no MAC addresses for just one VLAN? 

4 REPLIES
Hall of Fame Super Bronze

3750 MAC table

Type 'show vlan' and make sure Vlan 60 is on the L2 Vlan Database and shows as ACTIVE.

New Member

3750 MAC table

Yes it is there and active. 

60   GuestWirelessDMZ                 active    Gi2/0/1, Gi2/0/43

I wish the port-channels showed up in the show vlan.  If there any tuning (by allowed or pruning) of vlans it slows troubleshooting compared to other vendor switches where trunks are displayed.

Hall of Fame Super Bronze

3750 MAC table

show int trunk

New Member

3750 MAC table

My point exactly an extra step.  IMHO I'd like it to be displayed in the show vlan to keep it all together. 

Still not understanding why the MAC table is empty...

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