In a common setup, an IP phone is connected directly to the switch, while a PC or laptop is connected behind the phone. In this scenario, Voice VLAN helps separate voice traffic from regular data traffic and allows the switch to prioritize voice packets from the IP phone.
The goal of this configuration is to separate traffic between the IP phone and the PC without manually configuring individual VLAN tags on each device. The switch will handle voice and data traffic separately and forward it to the uplink with the required VLAN settings.
Example VLAN design:
| Traffic type | VLAN ID | Purpose |
|---|---|---|
| Data VLAN | 5 | PC / laptop traffic |
| Voice VLAN | 100 | IP phone traffic |
Note: VLAN IDs in this article are examples. Use the VLAN IDs required for your own network design.
Note: This article describes the configuration of Voice VLAN on standalone Zyxel switches. If you are looking for Voice VLAN configuration in Nebula or Vendor ID-based VLAN, please refer to the related articles: Zyxel Nebula Switch - Voice VLAN vs Vendor ID-based VLAN: Differences and Configuration
Expected IP phone behavior
The behavior of the IP phone depends on whether VLAN tagging is enabled on the phone and whether the configured VLAN ID matches the Voice VLAN on the switch.
| IP phone setting | Switch behavior | Required switch port setting |
|---|---|---|
| The IP phone is VLAN-enabled and uses the same VLAN ID as the Voice VLAN | The switch keeps the Voice VLAN tag and applies the configured priority setting to the IP phone traffic. The IP phone will only recognize tagged traffic. | The phone port must be tagged in the Voice VLAN. Enable Tx Tagging for this port in the Voice VLAN. |
| The IP phone is VLAN-enabled but uses a different VLAN ID than the switch Voice VLAN | The switch will not modify the VoIP traffic from the IP phone. | Check that the VLAN ID configured on the phone matches the Voice VLAN ID configured on the switch. |
| The IP phone is VLAN-disabled and sends untagged traffic | The switch assigns the Voice VLAN and priority setting to the IP phone VoIP traffic. The IP phone will send and receive untagged traffic. | The phone port must be untagged in the Voice VLAN. Disable Tx Tagging for this port in the Voice VLAN. |
If the IP phone does not behave as expected, verify the VLAN configuration on the phone, the Voice VLAN ID on the switch, and the Tx Tagging setting on the phone port.
Configuration (Create VLAN interfaces)
Create a VLAN for voice packet transmission, select ports that are connected to IP phone, and unselect Tx tagging as to save the effort of configuring VLAN on each phone.
SWITCHING > VLAN > VLAN Setup > Static VLAN > Add/Edit
Create a VLAN for voice packets transmission, select ports which are connected to IP phone, unselect Tx tagging as to save efforts of configuring VLAN on each phone.
| Create another VLAN for data packets, select member ports, and unselect Tx tagging. | Port 10, the uplink port, and Tx tagging should be enabled to transmit packets with VLAN tags |
Configure PVID to separate data packets from voice packets. PVID number should be the same as the VLAN number created for data packets.
Note! You can write PVID 5 on * which will make all ports the same PVID:
After setting PVID for data packets, the next step is to configure the “Voice VLAN” feature for the switch to identify the voice packets.
Configure Voice VLAN
Configure Voice VLAN number and priority to prioritize the voice packets. The Voice VLAN number should be the same as the VLAN number created earlier for voice service packets.
Specify the OUI addresses. OUI are the first 3 bytes of a MAC address that represent the vendor. By specifying the IP phone MAC address, the switch can identify voice traffic accordingly. Zyxel switch supports up to 6 vendor OUIs.
This guide demonstrates the ease of configuring Voice VLAN on standalone switches. In general, separating VLANs and determining rules for data and voice achieves the goal of prioritizing voice traffic without additional configuration on the IP phones.
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