The emerging demands of multimedia communications in Internet or intranet forces the Internet service providers to provide predictable or even guaranteed Quality of Service (QoS). The major critical issue for network researchers and service providers is how to provide high quality of communication services with limited bandwidth capacity. This study addresses various issues related to Voice over IP (VoIP) and voice over MPLS networks with IP QoS techniques, and provides a performance comparison. The simulation results reported identify the pros and cons of the two networks and find the best suitable service to provide guaranteed QoS for voice transmission.

Voice over Internet Protocol (VoIP) transmits voice packets over Internet Protocol (IP). The existing IP network is used for transmitting both data and voice in a cost-effective and reliable manner. VoIP uses a combination of different protocols to transmit voice signals over packet-switched network. Different codecs are used to transform the sampled voice data into a specific network-level representation and compress it for efficiency, which is reversed at the other end. Voice session control and data transmission protocols are used to set up, initiate, maintain and tear down communication between endpoints. VoIP has many issues like packet loss rate, delay, jitter and throughput. Table 1 shows various codecs used for VoIP (Singh et al., 2009). In the present paper, various issues related to VoIP and Voice over Multiprotocol Label Switching (MPLS) networks with IP QoS techniques are addressed.

Computer Sciences Journal, IP, MPLS, VoIP and QoS.