QOS requirement for Voice Transport in Packet Based Networks 2
How to have good QOS for voice services in a packet network?
- Insert Echo cancellation devices at the nearest points of the source of echo (2/4 wires hybrids and in the phone itself for )
- Implement mechanisms to give high priority to voice services by using priority mechanisms (voice packet will be handled before all non real time packets):
- This could be done at the network layer with the TOS/DS field appropriately set or at the data link layer (802.1 Q/P, ATM COS etc …)
- Try to have less than 150 ms of one way transmission time
- Limit jitter to less than 20 ms