MAC learning & L3 issue

[BobGreer65666]

Hi there,

Thanks for reading!

I have a Mitel PBX box direct connected to a C9200L.  The issue is the Mitel's mgmt IP is unreachable; doesn't ping-reply even from the switch.  Vlan 200 exists on the switch.  The trunk allows vlan 200.  The switch is learning the Mitel MAC address but no replies.  

A tech has validated the mgmt IP on the Mitel.

Seems the issue is in the Mitel box. 

Am I missing a troubleshooting step?

interface GigabitEthernet1/0/46
description MITEL
switchport trunk native vlan 200
switchport mode trunk

Vlan Mac Address Type Ports
---- ----------- -------- -----
200 0010.360a.8d4a DYNAMIC Gi1/0/46

GigabitEthernet1/0/46 is up, line protocol is up (connected)

Thanks!

Bob

[Richard Burts]

We do not have much detail to work with to understand this issue. If the interface is configured as a trunk is Mitel using vlans other than 200? What do you get in the output of show interface trunk?

Are there any other mac addresses associated with this interface?

Is this switch set up as layer 3 (ip routing enabled)? If so run debug for arp and see if there is any activity from Mitel?

[BobGreer65666 · Accepted solution]

Hi Richard,

Thanks for writing!

I ran a packet capture and see the PBX IP (properly configured) handling SIP traffic and I had a revelation: a bad assumption on my part about vlan 200.  The mgmt IP isn't in vlan 200.  It's in the default vlan 1.

I think there'd be no interruption if I changed the native vlan 200 command to native vlan 1 or negated the native vlan command.  What do you think?

Here's the switchport config:

interface GigabitEthernet1/0/46
description MITEL
switchport trunk native vlan 200
switchport mode trunk

Thanks again!

Bob

[Richard Burts]

Bob

I am glad that my comment pointed you in the right direction. Certainly the configuration needs to be changed to make vlan 1 the native vlan. I am not sure that I would go so far as to say NO interruption when you make the change. I would not be surprised if the interface performs a reset as part of implementing the change. I would expect any impact to be minimal. But I am not confident about no impact. Depending on your environment and how sensitive they are to interruptions (especially if this is a production environment) you might want to schedule a maintenance window to make this change.