C9300-48P MAC Address output

[Hiten Thakkar]

Hi,

We are deploying a boat load if C9300-48P loaded with Cisco IOS XE Software, Version 17.03.02a, RELEASE SOFTWARE (fc5) Cisco IOS Software [Amsterdam], Catalyst L3 Switch Software (CAT9K_IOSXE). We have Mitel phones for our VoIP. The following is a small snippet for a port configuration for VoIP and Data VLAN

interface GigabitEthernet2/0/16
switchport access vlan 140  (data)
switchport voice vlan 3055  (VoIP)
auto qos trust
spanning-tree portfast
service-policy input AutoQos-4.0-Trust-Cos-Input-Policy
service-policy output AutoQos-4.0-Output-Policy.

I have deliberately garbled the MAC Address for security reason.

Output of show mac address:

Vlan Mac Address Type Ports
---- ----------- -------- -----
140 0008.5d3c.wxyz  DYNAMIC Gi2/0/16
3055 0008.5d3c.wxyz DYNAMIC Gi2/0/16

0008.5d3c.wxyz is the MAC Address for MITEL phone. I was expecting that VLAN 140 will harvest the computer MAC Address and then VLAN 3055 will have the MITEL phone address. At least the Ruckus switches make the distinction. I am wondering whether the Cisco Switches make the distinction or not. Clearly from above it mimics that there is another mini hum or switch is connected? Please let me know what or how do I display two Distinct MAC addresses for the phone and computer? Your replies are highly appreciated in advance. Thanks!

[Reza Sharifi]

Hi,

Not sure about MITEL phones but with a Cisco phone connecting to a laptop if you run command 

sh mac address-table interface gigabitEthernet x/x/x

You will see 2 distinct MAC addresses each being in their corresponding VLAN.

HTH

[Hiten Thakkar]

That's what I expected and it is not.

[vencislav.metev]

Hi,

The way the phones work (or most of them) is first using data vlan (in your case vlan 140) to take IP address and config file in which should be configured which will be voice vlan, which will be ip address of the call manager. Then when it knows which is its voice vlan it is trying to take address from voice vlan and register to the call manager (or whatever is the telephone central management server).

So in that case you will see MAC address in both vlans because first time phone is using data vlan and then voice vlan.

After aging time expire and you don`t have updates coming from the phone in data vlan, this mac address will expire and you won`t see it unless you reload the phone and the process starts again.

When you connect a PC to the phone you will see its MAC address

I hope this answer your question.

Regards,

Ventsi

I ho

[Hiten Thakkar]

Makes Sense, since in certain ports I see 3 MAC: 2 x Phone in VoIP and Data and then a computer in Data VLAN. I haven't examined further if the time out occurs and the phone MAC address is flushed out from the DATA VLAN. Also not to discount your explanation post the phone has registered itself so it's MAC is live and won't it still be persistent and still show up in DATA VLAN.

In Ruckus Switches we never had the issue there was a clear distinction in show mac address-table .

Many Thanks for your reply appreciate it.