Monday, February 7, 2011

Quality of Service (part 5)

One of the key requirements for the widespread deployment of VoIP is the ability to offer a toll quality service equivalent to the existing PSTN. Indeed some carriers are even looking for Next-Generation Networks as a means for delivering much higher voice quality as a service.  Perceived Voice quality is very sensitive to three key performance criteria in a packet network, in particular: 
  • Delay
  • Jitter 
  • Packet loss
IP, by its nature, provides a best-effort service and does not provide guarantees about the key criteria. Therefore it is necessary to Implement a suitable QoS solution in the majority of cases where simple over provisioning cannot guarantee success. There are a large number of technologies that can be chosen to provide QoS support such as Diffserv, RSVP,MPLS and even ATM. However the objective of such a solution is always to guarantee prioritization of voice media streams over best-effort data, and to ensure that the voice service is not compromised by unforeseen traffic patterns.

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