JUNOS Enterprise Switching

Voice VLAN

An important step in IP telephony concerns separating the data traffic from the voice traffic, especially in a deployment scenario such as the one depicted previously in Figure 10-1. A feature called the voice VLAN can be used for this purpose. The voice VLAN allows for tagged and untagged traffic to be accepted, and also allows you to associate each type of traffic with distinct and separate VLANs. This helps to prioritize voice traffic over data traffic and deploy CoS.

If LLDP-MED is used, the CoS implementation is greatly simplified, as the IP phones will be dynamically associated with the appropriate voice VLAN as well as 802.1p values based on the forwarding class settings. This essentially allows for plug-and-play functionality. If LLDP-MED is not used, the configuration is more manual in nature.

First, define the voice VLAN and associated VLAN (see Chapter 5 for information on VLAN configuration). This example also uses an FC called expedited-forwarding, so that value will be sent to the IP phone if there is LLDP-MED support:

ethernet-switching-options {
    voip {
        interface ge-0/0/0.0 {
            vlan voice;
            forwarding-class expedited-forwarding;
        }
    }
}

lab@Ethanol> show configuration vlans
voice {
    vlan-id 100;
}

Warning

Prior to 9.3, the TLV for DSCP and LLDP-MED did not exist. This is tracked in PR 313953.

Next, apply the voice VLAN to the interface:

lab@Ethanol> show configuration interfaces ge-0/0/0
unit 0 {
    family ethernet-switching {
        vlan {
            members voice;
        }
    }

Then verify the