Quality of service

QoSquality-of-serviceQuality of Service (QoS)QoS (Quality of Service)qualitylevel of service qualityover-provisioningQOS-MPLSqualities of serviceService Quality
Quality of service (QoS) is the description or measurement of the overall performance of a service, such as a telephony or computer network or a cloud computing service, particularly the performance seen by the users of the network.wikipedia
484 Related Articles

Grade of service

call lossgradingservice
A subset of telephony QoS is grade of service (GoS) requirements, which comprises aspects of a connection relating to capacity and coverage of a network, for example guaranteed maximum blocking probability and outage probability.
In telecommunication engineering, and in particular teletraffic engineering, the quality of voice service is specified by two measures: the grade of service (GoS) and the quality of service (QoS).

Computer network

networkcomputer networkingnetworking
Quality of service (QoS) is the description or measurement of the overall performance of a service, such as a telephony or computer network or a cloud computing service, particularly the performance seen by the users of the network. In the field of computer networking and other packet-switched telecommunication networks, teletraffic engineering refers to traffic prioritization and resource reservation control mechanisms rather than the achieved service quality. In the field of computer networking and other packet-switched telecommunication networks, quality of service refers to traffic prioritization and resource reservation control mechanisms rather than the achieved service quality.
Overlay networks have also been proposed as a way to improve Internet routing, such as through quality of service guarantees to achieve higher-quality streaming media.

Erlang (unit)

ErlangErlang unitblocking
A subset of telephony QoS is grade of service (GoS) requirements, which comprises aspects of a connection relating to capacity and coverage of a network, for example guaranteed maximum blocking probability and outage probability.
To do this, a target is set for the grade of service (GoS) or quality of service (QoS).

Teletraffic engineering

traffic engineeringTeletraffic engineering in broadband networksEFCI
In the field of computer networking and other packet-switched telecommunication networks, teletraffic engineering refers to traffic prioritization and resource reservation control mechanisms rather than the achieved service quality.
The measurement of traffic in a public switched telephone network (PSTN) allows network operators to determine and maintain the quality of service (QoS) and in particular the grade of service (GoS) that they promise their subscribers.

Network congestion

congestion controlcongestioncongestion avoidance
The resulting absence of network congestion reduces or eliminates the need for QoS mechanisms.
Network congestion in data networking and queueing theory is the reduced quality of service that occurs when a network node or link is carrying more data than it can handle.

Traffic flow (computer networking)

flowflowspacket flow
Quality of service is the ability to provide different priority to different applications, users, or data flows, or to guarantee a certain level of performance to a data flow.
The concept is important, since it may be that packets from one flow need to be handled differently from others, by means of separate queues in switches, routers and network adapters, to achieve traffic shaping, fair queueing or Quality of Service.

Best-effort delivery

best effortbest-effortbest effort delivery
A best-effort network or service does not support quality of service.
Best-effort delivery describes a network service in which the network does not provide any guarantee that data is delivered or that delivery meets any quality of service.

Packet switching

packet-switched networkpacket switchedpacket-switched
In the field of computer networking and other packet-switched telecommunication networks, teletraffic engineering refers to traffic prioritization and resource reservation control mechanisms rather than the achieved service quality. In the field of computer networking and other packet-switched telecommunication networks, quality of service refers to traffic prioritization and resource reservation control mechanisms rather than the achieved service quality.
Packets are normally forwarded by intermediate network nodes asynchronously using first-in, first-out buffering, but may be forwarded according to some scheduling discipline for fair queuing, traffic shaping, or for differentiated or guaranteed quality of service, such as weighted fair queuing or leaky bucket.

Quality of experience

Quality of Experience (QoE)experienced quality
Other terms with similar meaning are the quality of experience (QoE), mean opinion score (MOS), perceptual speech quality measure (PSQM) and perceptual evaluation of video quality (PEVQ).
QoE has historically emerged from Quality of Service (QoS), which attempts to objectively measure service parameters (such as packet loss rates or average throughput).

Packet loss

losspacket droppingpacket loss rate
To quantitatively measure quality of service, several related aspects of the network service are often considered, such as packet loss, bit rate, throughput, transmission delay, availability, jitter, etc. For example, a required bit rate, delay, delay variation, packet loss or bit error rates may be guaranteed.
Packet loss is closely associated with quality of service considerations, and is related to the erlang unit.

Jitter

wanderphase jitterjitter buffer
To quantitatively measure quality of service, several related aspects of the network service are often considered, such as packet loss, bit rate, throughput, transmission delay, availability, jitter, etc.
PDV is an important quality of service factor in assessment of network performance.

Frame Relay

Frame-RelayframesLAPF
Examples are frame relay, asynchronous transfer mode (ATM) and multiprotocol label switching (MPLS) (a technique between layer 2 and 3).
An enterprise can select a level of service quality, prioritizing some frames and making others less important.

Throughput

maximum throughputasymptotic bandwidthBandwidth
To quantitatively measure quality of service, several related aspects of the network service are often considered, such as packet loss, bit rate, throughput, transmission delay, availability, jitter, etc.

Audio over Ethernet

Ethernet
Performance requirements may be met through use of a dedicated local area network (LAN) or virtual LAN (VLAN), overprovisioning or quality of service features.

Data link layer

Layer 2Data linkLayer-2
A number of attempts for layer 2 technologies that add QoS tags to the data have gained popularity in the past.

Differentiated services

Differentiated Services Code PointDSCPDifferentiated Services (DiffServ)
These bits were later re-defined as Differentiated services code points (DSCP).
Differentiated services or DiffServ is a computer networking architecture that specifies a simple and scalable mechanism for classifying and managing network traffic and providing quality of service (QoS) on modern IP networks.

PSQM

perceptual speech quality measure
Other terms with similar meaning are the quality of experience (QoE), mean opinion score (MOS), perceptual speech quality measure (PSQM) and perceptual evaluation of video quality (PEVQ).
This is very important to telephony providers who are mandated to maintain high Quality of Service standards.

IEEE P802.1p

IEEE 802.1p802.1pPriority Code Point
Ethernet optionally uses 802.1p to signal the priority of a frame.
Essentially, the task group provided a mechanism for implementing quality of service (QoS) at the media access control (MAC) level.

Packet delay variation

delay jitterjitterdelay variation
For example, a required bit rate, delay, delay variation, packet loss or bit error rates may be guaranteed.
For interactive real-time applications, e.g., voice over IP (VoIP), PDV can be a serious issue and hence VoIP transmissions may need quality of service-enabled networks to provide a high quality channel.

Integrated services

IntServ
In computer networking, integrated services or IntServ is an architecture that specifies the elements to guarantee quality of service (QoS) on networks.

Traffic contract

Peak Cell Rateparameter of a traffic contractUBR
A network or protocol that supports QoS may agree on a traffic contract with the application software and reserve capacity in the network nodes, for example during a session establishment phase.
These service categories provide a method to relate traffic characteristics and QoS requirements to network behaviour.

IEEE 802.11e-2005

802.11eIEEE 802.11ee
IEEE 802.11e-2005 or 802.11e is an approved amendment to the IEEE 802.11 standard that defines a set of quality of service (QoS) enhancements for wireless LAN applications through modifications to the media access control (MAC) layer.

IEEE 802.1Q

802.1QIEEE 802.1Q-2014802.1Q VLAN tag
At the MAC layer, VLAN IEEE 802.1Q can be used to carry 3 bit of essentially the same information.
The standard also contains provisions for a quality-of-service prioritization scheme commonly known as IEEE 802.1p and defines the Generic Attribute Registration Protocol.

Voice over IP

VoIPVoice over Internet Protocolvoice-over-IP
In particular, developers have introduced Voice over IP technology to allow computer networks to become as useful as telephone networks for audio conversations, as well as supporting new applications with even stricter network performance requirements.
It is a best-effort network without fundamental Quality of Service (QoS) guarantees.

Virtual LAN

VLANVLANsvirtual local area network
At the MAC layer, VLAN IEEE 802.1Q can be used to carry 3 bit of essentially the same information.
Since VLANs share bandwidth, a VLAN trunk can use link aggregation, quality-of-service prioritization, or both to route data efficiently.