Configuring Network101provide QoS simply based on the DiffServ class. The DSCP value ranges from 0 to 63 with eachDSCP specifying a particular per-hop behavior (PHB) applicable to a packet. A PHB refers to thepacket scheduling, queuing, policing, or shaping behavior of a node on any given packet.Four standard PHBs available to construct a DiffServ-enabled network and achieve QoS: Class Selector PHB – backwards compatible with IP precedence. Class Selector codepoints are of the form “xxx000”. The first three bits are the IP precedence bits. These classselector PHBs retain almost the same forwarding behavior as nodes that implement IPprecedence-based classification and forwarding. Expedited Forwarding PHB – the key ingredient in DiffServ model for providing alow-loss, low-latency, low-jitter and assured bandwidth service. Assured Forwarding PHB – defines a method by which BAs (Bandwidth Allocations) canbe given different forwarding assurances. Default PHB – specifies that a packet marked with a DSCP value of “000000” gets thetraditional best effort service from a DS-compliant node.VoIP is extremely bandwidth and delay-sensitive. QoS is a major issue in VoIP implementations, ,with regard to guaranteeing how that packet traffic is not delayed or dropped due tointerference from other lower priority traffic. VoIP can guarantee high-quality QoS only if thevoice, video and data packets are given priority over other kinds of network traffic. Yealink videoconferencing endpoints support the DiffServ model of QoS. DSCPs for voice, video and datapackets that can be specified respectively.Voice QoSTo make VoIP transmissions intelligible to receivers, voice packets should not be dropped,excessively delayed, or made to suffer varying delay. DiffServ model can guarantee high-qualityvoice transmission when the voice packets are configured to a higher DSCP value.Video QoSTo ensure acceptable visual quality for video, video packets emanated from the endpoint shouldbe configured with a high transmission priority.Data QoSTo ensure good call quality, data packets (e.g., SIP signaling and H.225 call signaling) emanatedfrom the endpoint should be configured with a high transmission priority.QoS feature parameters on the endpoint are described below.Parameter Description Configuration MethodAudio PrioritySpecifies the DSCP value for voicepackets.Valid Values: 0-63Default: 63Remote ControlWeb User Interface
