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New Member

Cannot see MAC address to connected port on Switch

 

Hello

 

I am experiencing a strange problem and would be grateful to have some advice on this.

 

I have a Switch (WS-C3750X-48P-S) version (flash:/c3750e-universalk9-mz.122-55.SE5).

 

I have two devices connected on two ports of the switch Gi1/0/41 and Gi1/0/42.

 

The configuration on the interfaces are as follows:

 

interface GigabitEthernet1/0/41
 description ### ALert Logic monitor port ###
 switchport access vlan 2
 switchport mode access
 load-interval 30
 duplex full
 spanning-tree portfast
end

sw01#sh run int Gi1/0/42
Building configuration...

Current configuration : 196 bytes
!
interface GigabitEthernet1/0/42
 description ### ALert Logic monitor port ###
 switchport access vlan 2
 switchport mode access
 load-interval 30
 duplex full
 spanning-tree portfast
end

But I cannot see them on the MAC address table

sw01#sh mac address-table int Gi1/0/41
          Mac Address Table
-------------------------------------------

Vlan    Mac Address       Type        Ports
----    -----------       --------    -----
sw01#sh mac address-table int Gi1/0/42
          Mac Address Table
-------------------------------------------

Vlan    Mac Address       Type        Ports
----    -----------       --------    -----

I was able to see that a couple of hours back

 

sh mac address-table int Gi1/0/41

          Mac Address Table

-------------------------------------------

 

Vlan    Mac Address       Type        Ports

----    -----------       --------    -----

   2    a036.9f36.d885    DYNAMIC     Gi1/0/41

Total Mac Addresses for this criterion: 1

sw01# sh mac address-table int Gi1/0/42

          Mac Address Table

-------------------------------------------

 

Vlan    Mac Address       Type        Ports

----    -----------       --------    -----

   2    a036.9f36.d884    DYNAMIC     Gi1/0/42

Total Mac Addresses for this criterion: 1

But since I could not see IP addresses getting associated to the MAC addresses, I did a shut / no shut on the port but have not been able to see the MAC address since. Any advice as to what may have gone wrong?

 

sw01(config)#int Gi1/0/41
sw01(config-if)#no shut
sw01(config-if)#int Gi1/0/42
sw01(config-if)#no shut
sw01(config-if)#^Z

 

 

Any hints would be much appreciated.

 

Thanks

 

Kaushik

 

8 REPLIES
New Member

Sorry but anyone seen this

Sorry but anyone seen this problem before?

Hey,it can happen with NIC

Hey,

it can happen with NIC teaming, as William said check the virtual mac associated, also the keep-alive intervals under the NIC teaming options.

Regards,
RS

New Member

Is it the switch where the

Is it the switch where the node is directly connected ?

Is the NIC at node side, working fine ?

 

Another fact to consider is, a mac will wipe itself out after the MAC-age timeout.

 

--

Parvesh

New Member

are those devices are working

are those devices are working or idle.may be the mac address table got cleared/expired and there is no traffic initiated or destined to those devices after that.

Regards

Prajith

New Member

Are the interfaces currently

Are the interfaces currently showing up/up? 

New Member

Yes, I think I may have found

Yes, I think I may have found the problem.

 

I think someone connected two NICs of the same device to the same Switch and VLAN. I think that may be causing this issue?

New Member

If they're using NIC teaming,

If they're using NIC teaming, a virtual MAC may have been assigned to the pair of NICs.  You'd need to get a list of any real and virtual MACs from the server admins to nail down the connections. 

Are those devices up and

Are those devices up and their NIC's are not in power save mode?

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