Newbie: Printer inaccessible to LAN

[BlueTongue]

Hi all,

I have this 3750 stack where all ports are configured as below.

The data runs on VLAN 1 and the voice runs on VLAN 100.

interface FastEthernet1/0/1

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 1,100

switchport mode trunk

Name: Fa1/0/1

Switchport: Enabled

Administrative Mode: trunk

Operational Mode: trunk

Administrative Trunking Encapsulation: dot1q

Operational Trunking Encapsulation: dot1q

Negotiation of Trunking: On

Access Mode VLAN: 1 (default)

Trunking Native Mode VLAN: 1 (default)

Administrative Native VLAN tagging: enabled

Voice VLAN: none

Administrative private-vlan host-association: none

Administrative private-vlan mapping: none

Administrative private-vlan trunk native VLAN: none

Administrative private-vlan trunk Native VLAN tagging: enabled

Administrative private-vlan trunk encapsulation: dot1q

Administrative private-vlan trunk normal VLANs: none

Administrative private-vlan trunk private VLANs: none

Operational private-vlan: none

Trunking VLANs Enabled: 1,100

Pruning VLANs Enabled: 2-1001

Capture Mode Disabled

Capture VLANs Allowed: ALL

The PCs and Polycom VOIP phones are plugged into the switch and they work fine.
However, if I plug printer(s) into the ports, they cannot be accessed.
I have to end up removing the trunk mode before it can work like below.

Name: Fa2/0/43

Switchport: Enabled

Administrative Mode: dynamic auto

Operational Mode: static access

Administrative Trunking Encapsulation: negotiate

Operational Trunking Encapsulation: native

Negotiation of Trunking: On

Access Mode VLAN: 1 (default)

Trunking Native Mode VLAN: 1 (default)

Administrative Native VLAN tagging: enabled

Voice VLAN: none

Administrative private-vlan host-association: none

Administrative private-vlan mapping: none

Administrative private-vlan trunk native VLAN: none

Administrative private-vlan trunk Native VLAN tagging: enabled

Administrative private-vlan trunk encapsulation: dot1q

Administrative private-vlan trunk normal VLANs: none

Administrative private-vlan trunk private VLANs: none

Operational private-vlan: none

Trunking VLANs Enabled: ALL

Pruning VLANs Enabled: 2-1001

Capture Mode Disabled

Capture VLANs Allowed: ALL

Can anyone please enlighten me?

Thanks.

[InayathUlla Sharieff]

HI,

What is the reason of  configuring Trunk port which connects to the Printer?

Regards

Inayath

[BlueTongue]

Good question: someone configured the switches some time ago and I just picked it up.
You are right.  There is no reason why it needs to be a trunk port for printers because they are not VLAN-aware devices.

I was hoping that I could just use the same config for all ports and for all equipment.

[InayathUlla Sharieff]

Hi Blue,

So just reconfigure the devices get the ports which are connected to the ports and have them configured as the access ports that should solve your issue.

HTH

Regards

Inayath

'

[lpassmore]

Hi BlueTongue

I don't think you have given us enough information to give you a direct answer.  Having said that it might really depend upon how the printer is configured and how it behaves.  If I might be permitted to make some assumptions, though, we might fix the environment.

Assumption 1.  PCs and printers have IP addresses in VLAN 1

Assumption 2.  Phones have IP addresses in VLAN 100

If this is the case, you are perhaps best configuring the switch ports as such:

interface FastEthernet 1/0/1

switchport mode access

switchport access vlan 1 (default)

switchport voice vlan 100

I suspect this will work for you.  If not, you need to put more information in the question (about the printers especially).  It might help to include make and model, configuration page information, some IP addressing and examples of what is and isn't working.  Also include the switch model and IOS version.

Cheers

LP

[BlueTongue]

Thanks lpassmore!

> Assumption 1. PCs and printers have IP addresses in VLAN 1

Yes, PCs and printers belong to the same subnet

> Assumption 2. Phones have IP addresses in VLAN 100
Yes, Phones belong to a different subnet

> interface FastEthernet 1/0/1

> switchport mode access

> switchport access vlan 1 (default)

> switchport voice vlan 100

Your suggestion is good and I will give it a try.

One quesiton: is there any pre-requisite (like phones supporting LLDP/MED ) for defining voice vlan in CISCO?

I am still a loss why all the ports were originally configured as trunk.

[lpassmore]

I see no reason it should not work as trunk, and prior to the switchport voice VLAN command this was the way to get IP phones working (especially non-Cisco).  But the above config works for NEC phones so don't see why Polycom should be a problem.  You might have to manually configure the voice and Data VLANs on the phone but if you do need to, you will be doing that now.

I actually suspect some issue with the printer - maybe it is semi-smart and using dynamic trunk protocol but not getting the VLAN information correct. 

[BlueTongue]

> I see no reason it should not work as trunk,

> and prior to the switchport voice VLAN command this was the way to get IP phones working (especially non-Cisco).

> interface FastEthernet1/0/1

> switchport trunk encapsulation dot1q

> switchport trunk allowed vlan 1,100

> switchport mode trunk

lpassmore, I understand why the above works for the VOIP phones because I could enter the VLAN ID onto them.

However, I don't understand how this will work for PCs or printers as they are not VLAN-aware.

Could you be kine enough to explain?

[lpassmore]

Wish I could explain.  I guess I don't fully understand the mechanics of the Voice VLAN configuration but in my experience the effect is that the port acts like a trunk when a device is connected that can handle it (such as  a phone).  Maybe somebody can give you a technically correct answer to that.

With the configuration that pdriver & I have suggested, the port will be an access port by default so the PC and printer should just work correctly.  When a phone is connected, the access VLAN becomes like the native and the voice VLAN data is tagged (just like an 802.1q trunk).  The phone should pass the native VLAN traffic to through to the PC port but use the tagged packets for the voice traffic.   I still don't see how this necessarily differs from a configured trunk port as I have connected many a PC (and phone) to a trunk port (configured just as you have) and it has worked fine for me.  However I guess that is no guarantee that every printer will work in that scenario.  Maybe it is seeing the trunk type connection and not enabling the interface correctly internally; maybe there are a lot of maybes.

If you really want to get into the mechanics of why the printers don't work with the trunk configuration, you will need to say what is wrong and what the symptoms are around the printer not working: 

Does it not bring the port up?

Does it connect but not pass traffic? 

Do you see a MAC address on the interface?

Do you see any data trying to come in from the printer?

Is there a valid ARP entry for the printer on the VLAN 1 router?

What is the printer configuration?

LP

[paul driver]

hello
Your ports need to be either data/voice access ports not trunked

If you have phones attached then assign port as a voice/data vlan
If you just have printer or end hosts then assign port as a data vlan

Default in fa0/1/0 ( this will clear old configurations)

Int fa0/10/
Switchport mode access
switchport access vlan xxxx ( Data vlan)
Switchport voice vlan xxxx (voice vlan)
No shut

Res
Paul



Sent from Cisco Technical Support iPad App

[BlueTongue]

> Your ports need to be either data/voice access ports not trunked

Yes, this is what I thought.
However, when I tested it again, I was surprised to see that defining the port as trunk like below works for both printer and phone (with PC piggyback)!!!!!

. interface FastEthernet1/0/1

. switchport trunk encapsulation dot1q

. switchport trunk allowed vlan 1,100

. switchport mode trunk

I always thought that a trunk port is purely for VLAN aware devices.
For the phone, because it is a VLAN aware device, when it sends voice packets out, they will be tagged with VLAN 100.  And when a packet comes in with a tag of VLAN 100 and the MAC address matches, the phone will receive the packet because the port is in the VLAN 100 membership.

However, for the PC, it is not VLAN aware, so what will happen?  Why does it work?

Can someone please explain?

> Switchport voice vlan xxxx (voice vlan)

Is there a requirement that the phone must be CDP enabled?
Also, I have a feeling that if a phone only has LLDP/MED, VOICE VLAN won't work.

[Abzal]

Hi,

I think if PC or IP phone is connected to the port with this configuration:

. interface FastEthernet1/0/1

. switchport trunk encapsulation dot1q

. switchport trunk allowed vlan 1,100

. switchport mode trunk

Both will use Native VLAN (VLAN #1) in your case Data VLAN. If  DHCP option for that data VLAN is not configured

(option 150 for the TFTP server) phone won't work.

>Is there a requirement that the phone must be CDP enabled?

Without CDP enabled on a port phone will not learn Voice VLAN id.

LLDP configuration:

configure terminal

lldp run

or

interface interface-id
lldp transmit
lldp receive

Hope it will help.

Best regards,
Abzal

[cadet alain]

Hi,

-the phone is tagging its frames( vlan 100) and the PC is not so it is considered as native vlan which by default is 1.

- on a trunk port like this one CDP won't tell the phone which vlan id it must tag its frames with, this only works with the voice vlan feature of the minitrunk port config.

Regards

Alain

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