SVP Voice Traffic Optimization

SpectraLink Voice is a voice protocol defined by Spectralink (a Wi-Fi phone company). To ensure Spectralink voice transmission quality on WLANs, SpectraLink defines SpectraLink Voice Priority (SVP) to describe the requirements of SpectraLink Voice on WLANs.

WLAN devices are required as follows when transmitting SpectraLink Voice packets:

The SpectraLink Voice packets are always in the header of the sending queue, so that they can be sent preferentially.
The air interface backoff time is 0.

Working Mechanism

After the SVP service is enabled, its working mechanism is as follows:

When receiving packets, an air interface identifies Spectralink Voice packets and modifies the priority of the Spectralink Voice packets.

In Spectralink Voice packets, the IP protocol number is 119. When receiving packets with the IP protocol number of 119, a WLAN device marks the packets as Spectralink Voice packets, and modifies the DSCP priority of the packets to 46 and 802.1p priority to 6.
When the air interface sends packets, the WLAN device schedules Spectralink Voice packets into the SVP-dedicated queue with the CWmin and CWmax of 0. The queue has the same default transmit opportunity (TXOP) limit and ACK policy as the Video Optimization (VO) queue.