The early standards for Ethernet defined a relatively simple structure for each frame that did not include a field for priority. An optional additional field, 4 bytes long, was introduced by the IEEE 802.1 working group (see 802.1D, 802.1Q and 802.1p). This optional field may sometimes be loosely referred to as the “VLAN tag”. Two bytes of the VLAN tag are assigned for Tag Control Information comprising a 3-bit Priority Code Point, a 1-bit CFI flag and a 12-bit VLAN ID. The field that we are interested in is the Priority Code Point (PCP) because it is used for VoIP QoS tagging in layer 2.
Prediction results can then be used to adapt either the network (more bandwidth,packet prioritising) or the voice stream (error correction, change VoIP codecs)to assure QoS.AFRIKAANSE OPSOMMING: Die kwaliteit van spraak oor die internet (VoIP) kommunikasie is afhanklik vandie netwerk wat gebruik word om spraakpakkies te vervoer tussen die eindpunte.
02/08/2011 · Greetings to everyone
Definitly QoS is the most important thing for a VoIP Phone Service Provider. In addition, I would like to add some tools available to test and solve qos issues below:
Enterprise QoS Solution Reference Network Design Guide
This paper studies the performance of Multiprotocol Label Switching (MPLS)networks for VoIP applications when applying both Traffic Engineering (TE) signal protocols and Quality of Service (QoS) algorithms. The used QoS algorithms are First-In First-Out FIFO), Priority Queuing (PQ), and Weighted Fair Queuing (WFQ). The study addresses different audio codecs including PCM (64 Kbps), GSM FR (13 Kbps), G.723.1 (5.3 Kbps), G.726 (16 Kbps), G.728 (16 Kbps), G.729 (8 Kbps) and IS-641(7.4 Kbps).In term of number of maintained calls, the results show that applying QoS algorithms improves the performance of the MPLS network with RSVP TE signal protocol more than that with CR-LDP TE signal protocol. The highest number of calls is achieved when applying both RSVP TE signal protocol with WFQ algorithm. In terms of voice end-to-end delay, voice packet delay variation, and voice jitter, the PQ algorithm gives the lowest values when applied with either CR-LDP or RSVP TE signal protocols.
Easy QoS Monitoring Software - PRTG | Paessler
QoS (Quality of Service) is a somewhat all-encompassing term and means different things to different people, even within the context of Voice over IP. The broader issues of audio quality on VoIP calls, echo cancellation and the mechanisms within end-points designed to compensate for packet loss and jitter are discussed in a different article . The QoS settings that this article seeks to explain are all directly related to frame and packet tagging for prioritisation of network traffic. Even restricting ourselves to this specific area, there is enough material to fill at least one decent sized book. In order to keep it to a manageable scale for this article I’m going to have to brush over some of the details very quickly. I apologise in advance if some experts out there find my condensed descriptions over-simplistic or inaccurate.