quality of service

• Quality of Service

https://store.theartofservice.com/the-quality-of-service-toolkit.html

Computer network Quality of service

1 Depending on the installation requirements, network performance is usually measured by the quality of

service of a telecommunications product. The parameters that affect

this typically can include throughput, jitter, bit error rate and latency.



1 The following list gives examples of network performance measures for a

circuit-switched network and one type of packet-switched network, viz.

ATM:



1 Circuit-switched networks: In circuit switched networks, network

performance is synonymous with the grade of service. The number of

rejected calls is a measure of how well the network is performing under

heavy traffic loads. Other types of performance measures can include

the level of noise and echo.



1 ATM: In an Asynchronous Transfer Mode (ATM) network, performance

can be measured by line rate, quality of service (QoS), data throughput, connect time, stability, technology, modulation technique and modem

enhancements.



1 There are many ways to measure the performance of a network, as each network

is different in nature and design. Performance can also be modelled instead of measured. For example, state transition diagrams are often used to model queuing performance in a circuit-switched network. These diagrams allow the network planner to analyze how the network will perform in each state, ensuring that the network will

be optimally designed.https://store.theartofservice.com/the-quality-of-service-toolkit.html

Storage area network - SAN Storage QoS (Quality of Service)

1 SAN Storage QoS (Quality of Service) is the coordination of capacity and performance in a dedicated storage

area network. This enables the desired storage performance to be

calculated and maintained for network customers accessing the

device.



1 Key factors that affect Storage Area Network

QoS(Quality of Service) are:



1 Bandwidth – The rate of data throughput available on the

system.



1 Latency – The time delay for a read/write

operation to execute.



1 Queue depth – The number of outstanding operations waiting to execute to the underlying disks

(Traditional or SSD).



1 QoS can be impacted in a SAN storage system by unexpected increase in data

traffic (usage spike) from one network user that can cause performance to decrease for other users on the same network. This can be known as the “Noisy Neighbor Effect.” When QoS services are enabled in a SAN

storage system, the “Noisy Neighbor Effect” can be prevented and network storage

performance can be accurately predicted.



1 Using SAN storage QoS is in contrast to using disk over-provisioning in a SAN

environment. Over-provisioning can be used to provide additional capacity to

compensate for peak network traffic loads. However, where network loads are not

predictable, over-provisioning can eventually cause all bandwidth to be fully

consumed and latency to increase significantly resulting in SAN performance

degradation.https://store.theartofservice.com/the-quality-of-service-toolkit.html

Orange S.A. - Controversies in UK regarding the quality of service

1 On 21 March 2007 Watchdog, a television series by the BBC focusing on consumer protection, published

the results from a broadband survey they held



1 In response to the problems with Orange UK broadband and 3G

broadband during March 2009 and April 2009 the 3G data network has

been upgraded to 3.5G and increased signal coverage



1 A consumer organisation forum web site known as OrangeProblems.co.uk focuses on

the poor level of service provided by Orange Broadband in the UK. Initially set up as WanadooProblems.co.uk, the site focuses

on the infamous Orange local loop unbundling and poor customer service but covers a wider range of Orange operations

such as lost email, significantly delayed SMTP and outages, suspicions of

eavesdropping, et al.https://store.theartofservice.com/the-quality-of-service-toolkit.html


1 Orange Mobile has been criticised during a Channel 4 News

investigation for a lack of security which potentially exposed customer

records to fraud.



1 In August 2007 Orange was criticised for summarily deleting email

accounts tied to old Freeserve and Wanadoo 'pay as you go' dial-up

accounts with no warning.



1 In August 2008, after well publicised problems with iPhone 3G performances,

customers compared their download speed and discovered that Orange in France was capping 3G download bandwidth. Orange admitted capping to 384kbit/s, well below the theoretical 7.2Mbit/s provided by the

iPhone. This issue was addressed by Orange with the complete uncapping of the

3G and 3G+ by Mid-September 2008.


Deep packet inspection - Quality of service

1 Applications such as peer-to-peer (P2P) traffic present increasing problems for broadband service

providers


Deep packet inspection - Quality of service

1 DPI allows the operators to oversell their available bandwidth while ensuring equitable

bandwidth distribution to all users by preventing network congestion. Additionally, a higher priority can be allocated to a VoIP or

video conferencing call which requires low latency versus web browsing which does not.

This is the approach that service providers use to dynamically allocate bandwidth

according to traffic that is passing through their networks.


Voice over IP - Quality of service

1 Communication on the IP network is perceived less reliable in contrast to the

circuit-switched public telephone network, as it does not provide a network-based

mechanism to ensure that data packets are not lost, and are delivered in sequential order. It is a best-effort network without

fundamental Quality of Service (QoS) guarantees. Therefore, VoIP

implementations may face problems with latency, packet loss and jitter.



1 By default, network routers handle traffic on a first-come, first-served

basis. Network routers on high volume traffic links may introduce latency that exceeds permissible thresholds for VoIP. Fixed delays cannot be controlled, as they are

caused by the physical distance the packets travel; however, latency can

be minimized by marking voice packets as being delay-sensitive with

methods such as DiffServ.



1 VoIP endpoints usually have to wait for completion of transmission of

previous packets, before new data may be sent



1 DSL modems provide Ethernet (or Ethernet over USB) connections to

local equipment, but inside they are actually Asynchronous Transfer Mode

(ATM) modems



1 However, a majority of DSL providers use only one VC for each customer,

even those with bundled VoIP service



1 ATM has substantial header overhead: 5/53 = 9.4%, roughly

twice the total header overhead of a 1500 byte Ethernet frame. This "ATM

tax" is incurred by every DSL user whether or not he takes advantage of multiple virtual circuits - and few can.



1 ATM's potential for latency reduction is greatest on slow links, because worst-case latency decreases with

increasing link speed



1 Voice, and all other data, travels in packets over IP networks with fixed maximum

capacity. This system may be more prone to congestion and DoS attacks than traditional circuit switched systems; a circuit switched system of insufficient capacity will refuse

new connections while carrying the remainder without impairment, while the

quality of real-time data such as telephone conversations on packet-switched networks

degrades dramatically.



1 Fixed delays cannot be controlled as they are caused by the physical

distance the packets travel. They are especially problematic when satellite circuits are involved because of the

long distance to a geostationary satellite and back; delays of 400–600

ms are typical.



1 When the load on a link grows so quickly that its switches experience queue overflows, congestion results

and data packets are lost



1 The receiver must resequence IP packets that arrive out of order and

recover gracefully when packets arrive too late or not at all



1 Although jitter is a random variable, it is the sum of several other random variables that are at least somewhat independent: the individual queuing

delays of the routers along the Internet path in question



1 It has been suggested to rely on the packetized nature of media in VoIP communications and transmit the stream of packets from the source

phone to the destination phone simultaneously across different

routes (multi-path routing)



1 A number of protocols have been defined to support the reporting of quality of service (QoS) and quality of experience (QoE) for VoIP calls



1 RFC 3611 VoIP metrics reports are exchanged between IP endpoints on an

occasional basis during a call, and an end of call message sent via SIP RTCP Summary

Report or one of the other signaling protocol extensions. RFC 3611 VoIP metrics reports are intended to support real time feedback related to QoS problems, the exchange of

information between the endpoints for improved call quality calculation and a

variety of other applications.



1 Rural areas in particular are greatly hindered in their ability to choose a VoIP system over

PBX


Public utility - Public utility quality of service for telecommunications

1 Maintaining the infrastructure for a public service or utility demands a set of sound practices to enable Quality of Service (QoS). Uniform

construction procedures especially must be followed by all parties. In particular, the recent boom in new

architectures/services in telecommunications demands a

whole new set of rules to maintain uninterrupted service.



1 With new construction in public utility areas, the basic considerations and

requirements relative to the construction practices and procedures are critical in a

telecommunications company operating area.



1 It is important that any construction should minimize the possibility of creating conditions

that



1 are hazardous to the general public and to any personnel working on, in,

or around supporting structures



1 could impair service or the restoration of service to customers of

all parties using the supporting structures.



1 A set of practices that promotes reliable network performance and

complies with all national codes; and that is consistent with current OSHA

Rules, EPA regulations, and DOT requirements; are imperative.



1 SR-1421, Blue Book - Manual of Construction Procedures provides a basis for developing productive Joint Use agreements and collaboration with other utilities such as power

supply companies.



1 There are many OSHA rules, EPA regulations, DOT requirements, and other agencies that can affect the

operations of a telecommunications company that are not directly

covered in SR-1421, although cross references where appropriate are present. These auxiliary issues are properly addressed in specific work

rules issued by individual companies.https://store.theartofservice.com/the-quality-of-service-toolkit.html

Quality of service

1 Quality of service


Quality of service

1 Quality of service (QoS) is the overall performance of a of telephony or

computer network, particularly the performance seen by the users of the

network.


Quality of service

1 To quantitatively measure quality of service several related aspects of the network service are often considered,

such as error rates, bandwidth, throughput, transmission delay,

availability, jitter, etc.


Quality of service

1 Quality of service is particularly important for the transport of traffic

with special requirements. In particular, much technology has

been developed to allow computer networks to become as useful as

telephone networks for audio conversations, as well as supporting new applications with even stricter

service demands.https://store.theartofservice.com/the-quality-of-service-toolkit.html

Quality of service - Definitions

1 Quality of service comprises requirements on all the aspects of a connection, such as service response

time, loss, signal-to-noise ratio, cross-talk, echo, interrupts,

frequency response, loudness levels, and so on



1 Quality of service guarantees are important if the network capacity is insufficient, especially for real-time streaming multimedia applications such as voice over IP, online games and IP-TV, since these often require

fixed bit rate and are delay sensitive, and in networks where the capacity is a limited resource, for example in

cellular data communication.https://store.theartofservice.com/the-quality-of-service-toolkit.html


1 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. During the

session it may monitor the achieved level of performance, for example the data rate and delay, and dynamically control scheduling

priorities in the network nodes. It may release the reserved capacity during a tear

down phase.



1 A best-effort network or service does not support quality of service. An

alternative to complex QoS control mechanisms is to provide high

quality communication over a best-effort network by over-provisioning

the capacity so that it is sufficient for the expected peak traffic load. The

resulting absence of network congestion eliminates the need for

QoS mechanisms.https://store.theartofservice.com/the-quality-of-service-toolkit.html


1 QoS is sometimes used as a quality measure, with many alternative

definitions, rather than referring to the ability to reserve resources.

Quality of service sometimes refers to the level of quality of service, i.e. the guaranteed service quality. High

QoS is often confused with a high level of performance or achieved

service quality, for example high bit rate, low latency and low bit error

probability.



1 An alternative and disputable definition of QoS, used especially in application layer services such as telephony and streaming video, is

requirements on a metric that reflects or predicts the subjectively

experienced quality


Quality of service - History

1 Conventional Internet routers and LAN switches operate on a best effort basis



1 With the advent of IPTV and IP telephony, QoS mechanisms are increasingly available to the end

user.



1 A number of attempts for layer 2 technologies that add QoS tags to the data have gained popularity in the past. Examples are frame

relay, asynchronous transfer mode (ATM) and multiprotocol label switching (MPLS) (a

technique between layer 2 and 3). Despite of this network technologies are in use today,

this kind of network lost the attention by the advent of Ethernet networks. Today Ethernet

is, by far, the most popular layer 2 technology. Ethernet may offer QoS through its 802.1p.



1 In Ethernet, virtual local area networks (VLAN) may be used to separate different QoS levels. For

example in fibre-to-the-home switches typically offer several

Ethernet ports connected to different VLANs. One VLAN may be used for

Internet access (low priority), one for IPTV (higher priority) and one for IP

telephony (highest priority). Different Internet service providers may use

the different VLANs.


Quality of service - Qualities of traffic

1 In packet-switched networks, quality of service is affected by various

factors, which can be divided into “human” and “technical” factors. Human factors include: stability of

service, availability of service, delays, user information. Technical

factors include: reliability, scalability, effectiveness, maintainability, grade

of service, etc.https://store.theartofservice.com/the-quality-of-service-toolkit.html


1 Many things can happen to packets as they travel from origin to

destination, resulting in the following problems as seen from the point of

view of the sender and receiver:



1 Due to varying load from other users sharing the same network resources,

the bit rate (the maximum throughput) that can be provided to

a certain data stream may be too low for realtime multimedia services if all

data streams get the same scheduling priority.



1 The routers might fail to deliver (drop) some packets if their data is corrupted or they arrive when their

buffers are already full. The receiving application may ask for this

information to be retransmitted, possibly causing severe delays in the

overall transmission.



1 Sometimes packets are corrupted due to bit errors caused by noise and

interference, especially in wireless communications and long copper

wires. The receiver has to detect this and, just as if the packet was

dropped, may ask for this information to be retransmitted.



1 It might take a long time for each packet to reach its destination, because it gets held up in long

queues, or takes a less direct route to avoid congestion. This is different from throughput, as the delay can

build up over time, even if the throughput is almost normal. In some cases, excessive latency can render an application such as VoIP or online

gaming unusable.https://store.theartofservice.com/the-quality-of-service-toolkit.html


1 Packets from the source will reach the destination with different delays.

A packet's delay varies with its position in the queues of the routers along the path between source and

destination and this position can vary unpredictably. This variation in delay is known as jitter and can seriously

affect the quality of streaming audio and/or video.



1 When a collection of related packets is routed through a network, different

packets may take different routes, each resulting in a different delay


Quality of service - Applications

1 A defined quality of service may be desired or required for certain types

of network traffic, for example:



1 Audio over Ethernet



1 Storage applications such as iSCSI and FCoE



1 Circuit Emulation Service



1 Safety-critical applications such as remote surgery where availability issues can be

hazardous



1 Network operations support systems either for the network itself, or for customers' business critical needs



1 Industrial control systems protocols such as Ethernet/IP which are used for real-time control of machinery



1 These types of service are called inelastic, meaning that they require a certain minimum level of bandwidth and a certain maximum latency to

function. By contrast, elastic applications can take advantage of however much or little bandwidth is

available. Bulk file transfer applications that rely on TCP are

generally elastic.https://store.theartofservice.com/the-quality-of-service-toolkit.html

Quality of service - Mechanisms

1 Circuit switched networks, especially those intended for voice

transmission, such as Asynchronous Transfer Mode (ATM) or GSM, have QoS in the core protocol and do not

need additional procedures to achieve it. Shorter data units and

built-in QoS were some of the unique selling points of ATM for applications

such as video on demand.https://store.theartofservice.com/the-quality-of-service-toolkit.html

Quality of service - Mechanisms

1 When the expense of mechanisms to provide QoS is justified, network customers and providers can enter into a contractual

agreement termed a service level agreement (SLA) which specifies guarantees for the

ability of a network/protocol to give guaranteed performance/throughput/latency bounds based on mutually agreed measures,

usually by prioritizing traffic. In other approaches, resources are reserved at each

step on the network for the call as it is set up.


Quality of service - Over-provisioning

1 An alternative to complex QoS control mechanisms is to provide high quality communication by generously over-provisioning a

network so that capacity is based on peak traffic load estimates



1 Commercial VoIP services are often competitive with traditional telephone service

in terms of call quality even though QoS mechanisms are usually not in use on the user's connection to their ISP and the VoIP

provider's connection to a different ISP. Under high load conditions, however, VoIP may

degrade to cell-phone quality or worse. The mathematics of packet traffic indicate that

network requires just 60% more raw capacity under conservative assumptions.



1 The amount of over-provisioning in interior links required to replace QoS depends on the number of users and

their traffic demands. This limits usability of over-provisioning. Newer

more bandwidth intensive applications and the addition of more

users results in the loss of over-provisioned networks. This then requires a physical update of the relevant network links which is an

expensive process. Thus over-provisioning cannot be blindly

assumed on the Internet.


Quality of service - IP and Ethernet efforts

1 Unlike single-owner networks, the Internet is a series of exchange points interconnecting private

networks. Hence the Internet's core is owned and managed by a number

of different network service providers, not a single entity. Its

behavior is much more stochastic or unpredictable. Therefore, research continues on QoS procedures that are deployable in large, diverse

networks.



1 There are two principal approaches to QoS in modern packet-switched IP networks, a parameterized system

based on an exchange of application requirements with the network, and a prioritized system where each packet

identifies a desired service level to the network.



1 Integrated services (“IntServ”) implements the parameterized

approach. In this model, applications use the Resource Reservation Protocol (RSVP) to request and

reserve resources through a network.



1 Differentiated services (“DiffServ”) implements the prioritized model.

DiffServ marks packets according to the type of service they desire. In

response to these markings, routers and switches use various queueing strategies to tailor performance to

expectations. Differentiated services code point (DSCP) markings use the

first 6 bits in the ToS field of the IP(v4) packet header.



1 Early work used the integrated services (IntServ) philosophy of reserving network

resources



1 In response to these markings, routers and switches use various

queuing strategies to tailor performance to requirements. At the IP layer, differentiated services code point (DSCP) markings use the 6 bits in the IP packet header. At the MAC layer, VLAN IEEE 802.1Q and IEEE

802.1p can be used to carry essentially the same information.



1 Routers supporting DiffServ configure their network scheduler to use

multiple queues for packets awaiting transmission from bandwidth constrained (e.g., wide area)

interfaces. Router vendors provide different capabilities for configuring this behavior, to include the number

of queues supported, the relative priorities of queues, and bandwidth

reserved for each queue.https://store.theartofservice.com/the-quality-of-service-toolkit.html


1 In practice, when a packet must be forwarded from an interface with

queuing, packets requiring low jitter (e.g., VoIP or videoconferencing) are given priority over packets in other

queues. Typically, some bandwidth is allocated by default to network

control packets (such as Internet Control Message Protocol and routing

protocols), while best effort traffic might simply be given whatever

bandwidth is left over.



1 At the Media Access Control (MAC) layer, VLAN IEEE 802.1Q and IEEE

802.1p can be used distinguish between Ethernet frames and

classify them. Queueing theory models have been developed on

performance analysis and QoS for MAC layer protocols.



1 One compelling example of the need for QoS on the Internet relates to congestion collapse


Quality of service - Protocols

1 The type of service (ToS) field in the IP(v4) header (now superseded by DiffServ)



1 The ITU-T G.hn standard provides QoS by means of “Contention-Free

Transmission Opportunities” (CFTXOPs) which are allocated to

flows which require QoS and which have negotiated a “contract” with the network controller. G.hn also supports non-QoS operation by

means of “Contention-based Time Slots”.



1 Audio Video Bridging


Quality of service - End-to-end quality of service

1 End-to-end quality of service can require a method of coordinating resource allocation between one autonomous system and another



1 Research consortia such as "end-to-end quality of service support over heterogeneous networks" (EuQoS, from 2004 through 2007) and fora

such as the IPsphere Forum developed more mechanisms for handshaking QoS invocation from

one domain to the next



1 It included a "Quality of Service

Theme" and published a book



1 In the services domain, end-to-end Quality of Service has also been

discussed in the case of composite services (consisting of atomic

services) or applications (consisting of application components).

Moreover, in cloud computing end-to-end QoS has been the focus of

various research efforts aiming at the provision of QoS guarantees across

the cloud service models.https://store.theartofservice.com/the-quality-of-service-toolkit.html

Quality of service - Circumvention

1 Strong cryptography network protocols such as Secure Sockets

Layer, I2P, and virtual private networks obscure the data

transferred using them. As all electronic commerce on the Internet

requires the use of such strong cryptography protocols, unilaterally

downgrading the performance of encrypted traffic creates an

unacceptable hazard for customers. Yet, encrypted traffic is otherwise unable to undergo deep packet

inspection for QoS.


Quality of service - Doubts about quality of service over IP

1 The Internet2 project found, in 2001, that the QoS protocols were probably

not deployable inside its Abilene Network with equipment available at

that time



1 The Abilene network study was the basis for the testimony of Gary

Bachula to the US Senate Commerce Committee's hearing on Network

Neutrality in early 2006. He expressed the opinion that adding

more bandwidth was more effective than any of the various schemes for accomplishing QoS they examined.



1 Bachula's testimony has been cited by proponents of a law banning

quality of service as proof that no legitimate purpose is served by such

an offering. This argument is dependent on the assumption that

over-provisioning isn't a form of QoS and that it is always possible. Cost

and other factors affect the ability of carriers to build and maintain permanently over-provisioned

networks.


Quality of service - Mobile (cellular) QoS

1 Mobile cellular service providers may offer mobile QoS to customers just as the fixed line PSTN services providers and Internet Service Providers (ISP)

may offer QoS. QoS mechanisms are always provided for circuit switched services, and are essential for non-

elastic services, for example streaming multimedia.



1 A phone call or other session may be interrupted after a handover, if the

new base station is overloaded. Unpredictable handovers make it

impossible to give an absolute QoS guarantee during a session initiation

phase.



1 The pricing structure is often based on per-minute or per-megabyte fee rather than flat rate, and may be

different for different content services.



1 A crucial part of QoS in mobile communications is Grade of Service,

involving outage probability (the probability that the mobile station is outside the service coverage area, or affected by co-channel interference,

i.e


Quality of service - Standards

1 Quality of service in the field of telephony, was first defined in 1994 in the ITU-T Recommendation E.800



1 Some QoS-related IETF Request For Comments (RFC)s are Definition of the

Differentiated services Field (DS Field) in the IPv4 and IPv6 Headers (RFC 2474), and

Resource ReSerVation Protocol (RSVP) (RFC 2205); both these are discussed above. The

IETF has also published two RFCs giving background on QoS: RFC 2990: Next Steps for the IP QoS Architecture, and RFC 3714: IAB Concerns Regarding Congestion Control

for Voice Traffic in the Internet.



1 The IETF has also published RFC 4594 Configuration Guidelines for

DiffServ Service Classes as an informative or "best practices" document about the practical

aspects of designing a QoS solution for a DiffServ network


Quality of service - Open source software

1 Linux Advanced Routing & Traffic Control (from 2000 to

2005)


Quality of service - Further reading

1 Deploying IP and MPLS QoS for Multiservice Networks: Theory and Practice by John Evans, Clarence Filsfils (Morgan Kaufmann, 2007,

ISBN 0-12-370549-5)



1 Lelli, F. Maron, G. Orlando, S. Client Side Estimation of a Remote Service

Execution. 15th International Symposium on Modeling, Analysis, and Simulation of Computer and

Telecommunication Systems, 2007. MASCOTS '07.



1 QoS Over Heterogeneous Networks by Mario Marchese (Wiley, 2007, ISBN 978-0-470-

01752-4)



1 XiPeng Xiao (September 8, 2008). Technical, Commercial and

Regulatory Challenges of QoS: An Internet Service Model Perspective. Morgan Kaufmann. ISBN 978-0-12-

373693-2.



1 RFC 1633: Integrated Services in the Internet

Architecture: an Overview



1 RFC 2475: An Architecture for Differentiated

services


Multitenancy - Quality of service

1 Multitenant applications are expected to provide adequate levels of security and robustness, which are provided by the operating system in

the case of multi-instance applications.


Outsourcing - Quality of service (QoS)

1 Quality of service is best measured through customer satisfaction

questionnaires which are designed to capture an unbiased view.


Computer networking - Quality of service

1 *Circuit-switched networks: In circuit switched networks, network

performance is synonymous with the grade of service. The number of

rejected calls is a measure of how well the network is performing under

heavy traffic loads. Other types of performance measures can include

the level of noise and echo.


Computer networking - Quality of service

1 *ATM: In an Asynchronous Transfer Mode (ATM) network, performance

can be measured by line rate, quality of service (QoS), data throughput, connect time, stability, technology, modulation technique and modem enhancements., Americas January

2003, Issue Highlights, Online Exclusive: Broadband Access

Maximum Performance, Retrieved on February 13, 2005.


Internet telephony - Quality of service

1 Communication on the IP network is perceived as less reliable in contrast

to the circuit-switched public telephone network because it does

not provide a network-based mechanism to ensure that data

packets are not lost, and are delivered in sequential order. It is a

best-effort network without fundamental Quality of Service (QoS)

guarantees. Therefore, VoIP implementations may face problems with latency (engineering)|latency,

packet loss, and jitter.



1 DSL modems provide Ethernet (or Ethernet over Universal Serial Bus|

USB) connections to local equipment, but inside they are actually

Asynchronous Transfer Mode (ATM) modems



1 ATM's potential for latency reduction is greatest on slow links, because worst-case latency decreases with

increasing link speed



1 Voice, and all other data, travels in packets over IP networks with fixed maximum

capacity



1 When the load on a link grows so quickly that its switches experience queue overflows, congestion results

and data packets are lost



1 It has been suggested to rely on the packetized nature of media in VoIP communications and

transmit the stream of packets from the source phone to the destination phone simultaneously

across different routes (multi-path routing).[http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?

arnumber=4520089 IEEE Multipath routing with adaptive playback scheduling for Voice over IP in Service Overlay Networks (Abstract)] In such a way, temporary failures have less impact on

the communication quality



1 A number of protocols have been defined to support the reporting of quality of service (QoS) and quality of experience (QoE) for VoIP calls



1 RFC3611 VoIP metrics reports are exchanged between IP endpoints on an occasional basis

during a call, and an end of call message sent via SIP RTCP Summary Report or one of

the other signaling protocol extensions. RFC3611 VoIP metrics reports are intended

to support real time feedback related to QoS problems, the exchange of information

between the endpoints for improved call quality calculation and a variety of other

applications.


Network Neutrality - Quality of service

1 Internet routers forward packets according to the diverse peering and

transport agreements that exist between network operators. Many networks using Internet protocols

now employ quality of service (QoS), and Network Service Providers

frequently enter into Service Level Agreements with each other embracing some sort of QoS.



1 There is no single, uniform method of interconnecting networks using Internet Protocol|IP, and not all

networks that use IP are part of the Internet. IPTV networks are isolated from the Internet, and are therefore not covered by network neutrality

agreements.



1 The IP datagram includes a 3-bit wide Precedence field and a larger

DiffServ Code Point that are used to request a level of service, consistent

with the notion that protocols in a layered architecture offer services

through Service Access Points



1 With the emergence of multimedia, VoIP, IPTV, and other applications

that benefit from low latency, various attempts to address the inability of

some private networks to limit latency have arisen, including the

proposition of offering tiered service levels that would shape Internet

transmissions at the network layer based on application type



1 He argues that since implementing quality of service doesn't require any

additional costs versus a non-QoS network, there's no reason

implementing quality of service should entail any additional fees



1 Xipeng Xiao covers the relationship between QoS and Network Neutrality

in the book Technical, Commercial and Regulatory Challenges of QoS:

An Internet Service Model Perspective.


France Telecom - Controversies in UK regarding the quality of service

1 On 21 March 2007 Watchdog (TV series)|Watchdog, a television

program|television series by the BBC focusing on consumer protection,

published the results from a broadband Survey methodology|

survey they held



1 A consumer organization|consumer organisation internet forum|forum web site known as

OrangeProblems.co.uk focuses on the poor level of service provided by Orange Broadband in the UK. Initially set up as WanadooProblems.co.uk, the site focuses on the infamous Orange local-loop unbundling|local loop unbundling and poor customer service but covers a wider range of

Orange operations such as lost email, significantly delayed SMTP and outages,

suspicions of eavesdropping, et al.



1 Orange Mobile has been criticised during a Channel 4 News

investigation for a lack of security which potentially exposed customer

records to fraud.[http://wayback.archive.org/web/20070621074012/http://www.chan

nel4.com/news/articles/business_money/concern%20over%20mobile%20security/172350

Channel 4 News]https://store.theartofservice.com/the-quality-of-service-toolkit.html


1 In August 2008, after well publicised problems with iPhone 3G

performances, customers compared their download speed and discovered

that Orange in France was capping 3G download bandwidth


Multitenant - Quality of service

1 Multitenant applications are expected to provide adequate levels of Computer security|security and Robustness (computer science)|

robustness, which are provided by the operating system in the case of

multi-instance applications.


Grid-tied electrical system - Quality of service

1 A key concept of this system is the possibility of creating an electrical

micro-system that is not dependent on the grid-tie to provide the high

level of service quality which is often delivered by a traditional mains

supply.


Grid-tied electrical system - Quality of service

1 Conversely if the mains supply of the region is unreliable, the local

generation system can be used to power important equipment.


Orange (telecommunications) - Controversies in UK regarding the quality of service

1 On 21 March 2007 Watchdog (TV series)|Watchdog, a television series

by the BBC focusing on consumer protection, published the results from

a broadband Statistical survey|survey they held


Orange (telecommunications) - Controversies in UK regarding the quality of service

1 A consumer organisation internet forum|forum web site known as

OrangeProblems.co.uk focuses on the poor level of service provided by Orange

Broadband in the UK. Initially set up as WanadooProblems.co.uk, the site focuses on the infamous Orange local loop unbundling

and poor customer service but covers a wider range of Orange operations such as lost email, significantly delayed SMTP and

outages, suspicions of eavesdropping, et al.


Femtocell - Quality of service

1 When using an ethernet or ADSL home backhaul connection, an Access Point Base Station must

either share the backhaul bandwidth with other services, such as Internet browsing, gaming consoles, set-top

boxes and triple play (telecommunications)|triple-play

equipment in general, or alternatively directly replace these

functions within an integrated unit. In shared-bandwidth approaches, which are the majority of designs currently

being developed, the effect on quality of service may be an issue.



1 The uptake of femtocell services will depend on the reliability and quality

of both the cellular operator’s network and the third-party

broadband connection, and the broadband connection’s subscriber

understanding the concept of bandwidth utilization by different applications a subscriber may use



1 A key issue recently identified is active traffic shaping by many ISPs on the underlying

transport protocol IPSec. UK-based femtocell benchmarking company Epitiro have published

whitepapers about these IP-focused QoS issues.Newson, A. (November 25, 2008).

[http://www.thinkfemtocell.com/downloads/white-papers/11-epitiro-femtocell-deployment-guide/download.html Femtocell Deployment

Guide]. ThinkFemtoCell.com. Epitiro.


SMS Banking - Quality of service in SMS banking

1 Because of the concerns made explicit above, it is extremely important that SMS gateway

providers can provide a decent quality of service for banks and

financial institutions in regards to SMS services


Utility companies - Public utility quality of service for telecommunications

1 Maintaining the infrastructure for a public service or utility demands a set of sound practices to enable

Quality of Service (QoS). Uniform construction procedures especially must be followed by all parties. In particular, the recent boom in new

architectures/services in telecommunications demands a

whole new set of rules to maintain uninterrupted service.



1 * are hazardous to the general public and to any personnel working on, in,

or around supporting structures



1 * could impair service or the restoration of service to customers of

all parties using the supporting structures.



1 [http://telecom-info.telcordia.com/site-cgi/ido/docs.cgi?

ID=SEARCHDOCUMENT=SR-1421 SR-1421, Blue Book - Manual of

Construction Procedures] provides a basis for developing productive Joint Use agreements and collaboration with other utilities such as power

supply companies.


Bharat Sanchar Nigam Limited - Quality of Service

1 BSNL goes by the motto Connecting India, faster and displays the same at

their homepage. BSNL offers seamless coverage in almost all urban and rural areas of India.


SANoIP - SAN Storage QoS (Quality of Service)

1 *Bandwidth (computing)|Bandwidth – The rate of data throughput available on the

system.



1 *Latency (engineering)|Latency – The time delay for a read/write operation to execute.



1 *Queue depth – The number of outstanding operations waiting to execute to the underlying disks

(Traditional or SSD).


Specialized Mobile Radio - Quality of service

1 In SMR systems, many factors affect the quality of service. This may include the capacity of the radio

system versus the number of radio units using the system. A talkative user community may cause busy

signals while a disciplined, professional group of SMR users may

keep channels idle.



1 Some systems experience seasonal peaks



1 Siting of the system affects coverage: the system Antenna

(radio)|antennas should overlook the desired coverage area. Federal Communications Commission

regulations require systems using the same radio frequency to be spaced 70 miles from one another or do an engineering study to confirm there will be no interference from closer

spacing. https://store.theartofservice.com/the-quality-of-service-toolkit.html


1 Maintenance practices also can affect quality. In some systems, the

operator may remove one channel of a trunked system from service to perform repairs. In a heavily-used

system, this could cause busy signals.



1 Engineering documentation for these systems suggests another evaluation would be delivered audio quality. This

is a measurement of the sound quality over all of the involved pieces of communications equipment from

end to end. The first clue this may be an issue is that radio users with

normal hearing have trouble understanding others when speaking

over the radio.https://store.theartofservice.com/the-quality-of-service-toolkit.html

Videotelephony - Categories by cost and quality of service

1 Quality of service can range from low to very high, including High-definition video|high definition video available

on the latest model webcams



1 * Videophones –low to midrange cost. The earliest standalone models

operated over either plain Plain old telephone service|POTS telephone

lines on the PSTN telephone networks or more expensive ISDN

lines, while newer models have largely migrated to Internet protocol

line service for higher image resolutions and sound quality. Quality

of service for standalone videophones can vary from low to

high;



1 * Videoconferencing|Videoconferencing systems –

midrange cost, usually utilizing multipoint control units or other

bridging services to allow multiple parties on a videoconference calls.

Quality of service can vary from moderate to high;



1 * Telepresence|Telepresence systems –highest capabilities and highest cost. Full

high-end systems can involve specially built teleconference rooms to allow expansive views with very high levels of audio and video fidelity, to permit an 'immersive'

videoconference. When the proper type and capacity transmission lines are provided between facilities, the quality of service

reaches state-of-the-art levels.


Quality-of-service - End-to-end quality of service

1 RSVP is an end-to-end principle|end-to-end bandwidth reservation

protocol. The traffic engineering version, RSVP-TE, is used in many

networks to establish traffic-engineered Multiprotocol Label Switching (MPLS) label-switched

paths.



1 Research consortia such as end-to-end quality of service support over heterogeneous networks (EuQoS, from 2004 through 2007) and fora such

as the IPsphere Forum[http://www.tmforum.org/ipsphere/

IPSphere: Enabling Advanced Service Delivery] developed more mechanisms for handshaking QoS invocation from one domain to the next.

IPsphere defined the Service Structuring Stratum (SSS) signaling bus in order to

establish, invoke and (attempt to) assure network services.



1 A broader European project called Architecture and design for the

future Internet known as 4WARD had a budgest estimated at 23.4 million Euro and was funded from January

2008 through June 2010.



1 It included a Quality of Service Theme and published a

book.



1 Varvarigou, An innovative Workflow Mapping Mechanism for Grids in the frame of Quality of Service, Elsevier

Future Generation Computer Systems, Vol


Quality-of-service - Doubts about quality of service over IP

1 The Abilene network study was the basis for the testimony of Gary Bachula to the

United States Senate Committee on Commerce, Science and Transportation|

US Senate Commerce Committee's hearing on Network Neutrality in early 2006. He expressed the opinion that adding more bandwidth was more

effective than any of the various schemes for accomplishing QoS they examined.


Vonage - Quality of service and equipment compatibility

1 VoIP service relies upon consistent broadband-ISP uptime and VoIP-equipment compatibility with the

ISP's modem


Vonage - Quality of service and equipment compatibility

1 Vonage implements Voice over IP sending audio via Real-time transport

protocol|RTP and signaling via Session Initiation Protocol|SIP.


Media independent handover - Quality of Service (QoS)

1 Short-lived sessions such as accessing a single web page typically

do not require handover or QoS. Longer duration sessions, which may well require handover, such as VoIP, audio/video streaming (including live

TV and VoD), and VPNs, typically have QoS requirements including delay, delay variation and packet

loss. https://store.theartofservice.com/the-quality-of-service-toolkit.html


1 It is important that QoS is maintained, not just before and after

a handover, but also during the handover, and this can be achieved

by using MIH to plan ahead



1 QoS is handled differently by each technology, including both the

wireless access technologies and also IP, which has two QoS

approaches, DiffServ and IntServ



1 MIH can be used to exchange information about service class and QoS parameter availability from one wireless technology to another and to the IP layer. One source of such

information is performance measurements made by the wireless

layer, e.g. 802.11k for WiFi and 802.16f for WiMAX.


Cross-layer optimization - Adjusting quality of service

1 Cross-layer optimization shall contribute to an improvement of quality of services under various

operational conditions. Such adaptive quality of service management is currently subject of various patent

applications, as e.g.[http://www.patentstorm.us/paten

ts/7339897.html Cross-layer integrated collision free path routing

- US Patent 7339897] https://store.theartofservice.com/the-quality-of-service-toolkit.html


1 The cross-layer control mechanism provides a feedback on concurrent quality information for the adaptive setting of control parameters. The

control scheme apply



1 * the observed quality parameters



1 * a fuzzy logic based reasoning about applying the appropriate control strategy



1 * the statistically computed control input to parameter settings and mode switches


Traffic contract - Quality of Service (QoS) Parameters

1 A set of parameters are negotiated when a connection is set up in an

ATM network. These parameters are used to measure the Quality of

Service|QoS of a connection and quantify end-to-end network

performance at the ATM layer. The network should guarantee the

negotiated QoS by meeting certain values of these parameters.



1 *Cell Transfer Delay (CTD). The delay experienced by a cell between the time it takes for the first bit of the

cell to be transmitted by the source and the last bit of the cell to be

received by the destination. Maximum Cell Transfer Delay (Max CTD) and Mean Cell Transfer Delay

(Mean CTD) are used.



1 *Peak-to-peak Cell Delay Variation (CDV). The difference between the

maximum and minimum CTD experienced during the connection.

Peak-to-peak CDV and Instantaneous CDV are used.



1 *Cell Loss Ratio (CLR). The percentage of cells that are lost in

the network due to error or congestion and are not received by

the destination.


Cellular traffic - Quality of Service targets

1 At the time that the cells of a radio subsystem are designed, Mobile QoS|Quality of Service (QoS) targets are

set, for: traffic congestion and blocking, dominant coverage area,

C/I, dropped call rate, handover failure rate, overall call success

rate, ...


Water supply and sanitation in Guatemala - Quality of service

1 The water and sanitation sector in Guatemala is characterized by “low

coverage, poor Water_supply#Service_quality|quality

services, and deteriorating physical assets,” related to a need for increased investments in basic infrastructures. Population growth,

agricultural expansion, unevenly distributed services, and polluted sources have

contributed to the inability of citizens to access adequate amounts of clean water.


Internet phone - Quality of service

1 VoIP endpoints usually have to wait for completion of transmission of previous packets before new data

may be sent


Internet phone - Quality of service

1 Voice, and all other data, travels in packets over IP networks with fixed maximum capacity. This system may be more prone to congestion and Denial-of-service attack|DoS attacks than traditional circuit switched systems; a circuit switched system of insufficient capacity will refuse new connections while carrying the remainder without impairment, while the

quality of real-time data such as telephone conversations on packet-switched networks

degrades dramatically.


Orange Mobile - Controversies in UK regarding the quality of service

1 On 21 March 2007 Watchdog (TV series)|Watchdog, a television

program|television series by the BBC focusing on consumer protection,

published the results from a broadband Survey methodology|

survey they held


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