What is Voice VLAN | Basics, and Common Implementation Methods

We explain the very basics of voice VLAN in this article along with its working and different ways to set it up. Keep reading to learn more.

Introduction:

Most of us have heard the term called LAN which is a linked environment that spans one or more buildings and connects computing devices that are close to one another using ethernet and Wi-Fi technologies. LAN is one of the most fundamental elements of the worldwide networked environment, both for consumers and businesses. When one or more LANs are grouped to interact with one another, they are really in a distinct LAN segment since the link is logical rather than physical, also termed as VLAN. 

Users and network computers can connect and share resources in the broadcast domain thanks to VLAN which refers to a set of LANs that are virtually connected and operate together. Scalability, security, and simplicity of network administration are the three. VLAN comes in many different types as well which are differentiated according to the sorts of devices they link, the architecture they are built on, and the media they employ, local area networks may be categorized. One of them is Voice VLAN which needs to be discussed here.

What is Voice VLAN: 

When voice traffic is broadcast alongside other traffic, the integrity of the voice traffic is ensured via a voice VLAN (also termed as Auxiliary VLAN or AUX VLAN) which is a virtual local area network created solely for the user's speech data streams. To put it another way, an AUX VLAN will be given priority and broadcast with a higher forwarding priority if other services are being offered concurrently. 

Voice traffic is provided with a separate VLAN using AUX VLAN. Since voice traffic is separate from other network traffic, the network is not slowed down by it. You must enable the AUX VLAN in your VOIP-enabled phone for the AUX VLAN and PC to function together. To do this, speech traffic is given its subnet, which is then assigned to the phone. Due to the added security, they offer, AUX VLANs are a crucial part of VolP networks.

A dedicated AUX VLAN is needed to guarantee voice-over IP quality (delay of less than 150 ms over the network) since this will protect bandwidth for other applications. With the aid of a dedicated AUX VLAN, the company uses voice-over IP in which both voice quality and other apps' bandwidth will be protected. 

There are mainly two ways to enable AUX VLAN on your network; The first is direct wiring but from an access switch using two distinct cables designated for two distinct VLANs, such as an access VLAN for computers and an AUX VLAN for VOIP. In this method, the switch loses two ports as a result of this strategy. and the second one is using VOIP data via the Native VLAN technique. Both native VLAN data and tagged data are sent through the trunk port. So, both the access VLAN and the native VLAN may be used as the AUX VLAN.

How does Voice VLAN work?

The initial step in recognizing speech data streams is to determine the source MAC addresses of the received packets or the VLAN tags of the packets. Based on the source MAC address in the data packet, a network switch may detect whether a data stream is a speech stream. 

If the source MAC address matches the configured OUI, the switch will either add a tag for the AUX VLAN to the packet and increase its priority or if it doesn't, it will add a tag for the PVID and leave the packet unprioritized.

This setup has its advantages in the system; first, your VoIP devices won't have to deal with all the broadcasts and other traffic from the data VLAN directly when several VLANs are set and trunked on the uplinks with 802.1Q on a network switch. Second, in some situations, an AUX VLAN can make network configuration simpler by making it simpler to install TFTP and DHCP services for VoIP phones and designate packets for QoS. thirdly, distinct voice services can be given a high priority using a voice VLAN to prioritize them.

These features for dedicated AUX VLAN are also present in modern switches in which an IP phone and a user's PC are linked to a single switch port are supported by these switches. Administrators of these devices frequently decide to handle VoIP communications differently from user data traffic.  

A method must be able to distinguish between voice communication and ordinary user data traffic to do this. For this, the AUX VLAN feature is employed which makes it possible for a single access port to receive both tagged and untagged speech and data traffic while associating each kind of traffic with a unique and independent VLAN. This allows speech traffic to be handled differently and, in most cases, with a greater priority than regular user data traffic.