VLAN: VLAN MISMATCH ISSUE


TOPICS

SCENARIO

TROUBLESHOOTING STEPS


 

SCENARIO

There is device called Video Conferencing Unit ( or simply VC unit), attached with Switch port.

User is not able to access this VC unit.

We need to troubleshoot to make this VC unit accesible by user.


 

TROUBLESHOOTING STEPS

DETAILS GIVEN BY USER

Got details of IP assigned to VC unit, 10.149.233.133/24

 

Now, we have to make POA ( Plan Of Action ) to Troubleshoot Issue

  1. Need to confirm Switch port on which VC unit is connected
  2. After confirming Switch Port, we will confirm the Switch port configuration

 

FIRST POINT

I turned on switch port monitoring at Switch.

To Turn On the monitoring, use command: terminal monitor, on the switch without entering into the config mode

I asked User to simply Turn On/ Turn Off the connected VC unit, so that i can receive the Switch port logs

Logs

=========

Jul 31 16:47:35 CDT: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/30, changed state to down

Jul 31 16:47:36 CDT: %LINK-3-UPDOWN: Interface FastEthernet0/30, changed state to down

Jul 31 16:47:44 CDT: %LINK-3-UPDOWN: Interface FastEthernet0/30, changed state to up

Jul 31 16:47:45 CDT: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/30, changed state to up

==========

Now, Switch port is confirmed, FastEthernet0/30

 

SECOND POINT

Checking Switch Port Configuration

Logs

=========

sw_3rd_07#sh running-config int fastEthernet 0/30

interface FastEthernet0/30

description 3rd Floor Data

power inline consumption 6300

power inline auto max 7700

switchport access vlan 31

switchport mode access

=========

Here, we need to confirm Subnet assigned to VLAN 31.

But, the switch on which this VC unit is assigned is Layer 2.

So, we need to find the Layer 3 Switch in the network, where Layer 3 VLAN’s are formed, to find out the Subnet assigned to VLAN 31.

 

So, I did traceroute to find the Layer 3 switch

Logs

===========

sw_3rd_07#traceroute 10.146.1.254

Type escape sequence to abort.
Tracing the route to 10.146.1.254

1 10.149.231.2 0 msec 0 msec 0 msec <———- This is the Layer 3 Switch

===========

After reaching the Layer 3 switch, i am able to get the detail of Subnet assigned to VLAN 31

which is 10.149.232.0/24

 

Mismatch

Fastethernet 0/30 is part of VLAN 31, VLAN 31 assigned subnet is 10.149.232.0/24

IP assigned to VC unit is 10.149.233.133/24which belongs to VLAN 32.

 

Solution

Port Fastethernet 0/30 is now made part of VLAN 32, instead of VLAN 31. This solution worked out.


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