User perceived quality-of-service for voice-over-IP in a heterogeneous multi-domain network environment

One of the main barriers to the commercial success of Voice-over-IP' (VoIP) services beyond a single domain (e.g., a company intranet, a single operator's domain) as a viable alternative to the classical voice telephony services is Quality-of-Service (QoS). The ability to deliver QoS is particularly challenging in next-generation networks, where VoIP services will be accessible via a variety of end-device types and over sequences of heterogeneous network domains, each with their specific QoS-mechanisms and owned by different competing network operators that will negotiate Service Level Agreements (SLAs) amongst each other. In this paper, we provide a method to effectively realize end-to-end QoS for VoIP as perceived by the end user in an environment in which multiple business domains are involved. To this end, we first present a quantitative model for the relation between (1) the end-to-end QoS at the end-user perception level, (2) the QoS requirements to network infrastructure given the specifies of the end user terminal, and (3) the SLAs negotiated at the network level between the different domain owners. Second, we show how the concept of a per-domain QoS certificate can help to guarantee predictable QoS for VoIP traffic over their network domains. This enables VoIP service providers to realize the desired perceived QoS levels for both intra and inter-domain VoIP sessions. This paper provides a simple and practically feasible approach for VoIP service providers to identify which network level SLAs need to be negotiated with other parties to realize the desired QoS level to their customers.