How to create a Voice VLAN on GS1900 Series switch?

Zyxel_Kay

This article will contain solutions on how to configure Voice over IP (VoIP). Two methods will be discussed: Voice VLAN and LLDP-MED. Voice VLAN is a form of Quality of Service (QoS). The Zyxel Voice VLAN configures which range of source MAC address should correspond to a VLAN with an administratively configured priority. LLDP-MED utilizes the IP Phone’s LLDP packets to determine which VLAN the device’s packets should belong to. Both methods are capable of performing autoprioritization. This improves the quality of voice traffic and avoid miscommunication between two recipients.

Topology:

In this scenario, we aim to connect three IP phones to the GS1900-8 switch. Port 1 of the switch is linked to the DHCP server, while Ports 2-4 are designated for the IP phones.

Configuration Method 1: Voice VLAN

The Zyxel Voice VLAN feature utilizes a configured OUI (Organizationally Unique Identifier) to categorize packets into the Voice VLAN based on source MAC addresses. This approach significantly enhances VoIP traffic management.

Procedure:

1. Navigate to Configuration > VLAN > VLAN, and click the Add button to create a VLAN for VoIP.
   
   • VLAN List: Enter the VLAN ID numbers
   • VLAN Name Prefix: Enter a prefix for the VLAN name
     
     Once completed, you'll see that the VLAN has been successfully created.
     
2. Configure the VLAN10 Port at Configuration > VLAN > VLAN Port. Since Port 1 is connected to the server, setting it as "tagged" allows traffic from VLAN10 to pass through it. Here are the Membership options:
   • Forbidden: to prohibit the port from joining this VLAN group
   • Excluded: for the port to dynamically join this VLAN group
   • Tagged: to set the the port TX tag status to tagged in the VLAN
   • Untagged: to set the port TX tag status to untagged in the VLAN
     
3. Create the Voice VLAN at Configuration > VLAN > Voice VLAN > Global tab.
   
4. In the OUI tab, add the first 3 bytes of every unique MAC address for every connected phone to the OUI table.
   
   Click the Add button to insert a new vendor's OUI.
   
5. In the Port tab, select the ports where you want to apply the OUI method for tagging the Voice VLAN.
   
   Then change their state to “Enable”.
   
   After applying, you will notice that the port states have changed to “Enable”.
   
6. Now you can connect your IP Phones to the designated ports. Your IP Phone should be able to obtain a DHCP configuration in the VLAN10 segment of the DHCP Server.

Configuration Method 2: LLDP-MED

LLDP-MED (Link Layer Discovery Protocol for Media Endpoint Devices) is another method for implementing QoS. It allows the Zyxel switch to configure specific parameters of directly connected LLDP-MED supported IP phones, such as their VLAN and priority. Some IP phones only allow certain parameters to be configured using LLDP-MED. This is accomplished by configuring the LLDP-MED Network Policy of the Zyxel switch.

Procedure:

1. Create VLAN10 for VoIP. Assign ports leading to other IP Phones and the DHCP and SIP servers. The PVID of the ports doesn't need to be considered.
2. Navigate to  Configuration > LLDP > Global, and make sure that the LLDP configuration is active.
   
3. Create a LLDP-MED Network policy: Configuration > LLDP > MED Network Policy
   
   Click the Add button to create a new policy.
   
4. Select the ports where you want to advertise this policy at Configuration > LLDP > MED Port.
   
   Choose the ports connected to IP Phones and click the Edit button. Then enable the network policy on ports to the IP Phones.
   
5. Now you can connect your IP Phones to the designated ports. Your IP Phone should be able to obtain a DHCP configuration in the VLAN10 segment of the DHCP Server.

Verification

1. To verify that this is working, navigate to Monitor > MAC Table and check the MAC table. The IP Phone’s MAC address should be associated with VLAN10.
   
2. Enter the web GUI and go to Maintenance > Diagnostic > PING. Use the switch to ping the IP Phone. The switch should successfully ping the IP Phone.
   

What Could Go Wrong

1. If the MAC address of the IP Phone is not assigned to VLAN10 successfully, please check if the IP Phone supports LLDP-MED. LLDP-MED must be enabled on the switch.
2. Since the IP Phone is assigned a VLAN ID via the function of the Network Policy in LLDP-MED, the voice traffic from the switch must be tagged back to the IP Phone. Port 1 in VLAN10 on the Switch should be tagged out so that the Switch can ping the IP Phone successfully.
3. Since the IP Phone is assigned a VLAN ID via the function of the Network Policy in LLDP-MED, please make sure the IP Phone either supports LLDP-MED or has LLDP-MED enabled.