text:
Metaphase
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Chromosomes lined up on the metaphase plate. Two views with the metaphase plate rotated 60°.
Metaphase (from the Greek μετά, "adjacent" and φάσις, "stage") is a stage of mitosis in the eukaryotic cell cycle in which chromosomes are at their second-most condensed and coiled stage (they are at their most condensed in anaphase).[1] These chromosomes, carrying genetic information, align in the equator of the cell before being separated into each of the two daughter cells. Metaphase accounts for approximately 4% of the cell cycle's duration.[citation needed] Preceded by events in prometaphase and followed by anaphase, microtubules formed in prophase have already found and attached themselves to kinetochores in metaphase.
Metaphase in cells (here an animal cell) are characterized by the arrangement of chromosomes at the equatorial plane of the cell
In metaphase, the centromeres of the chromosomes convene themselves on the metaphase plate (or equatorial plate),[2] an imaginary line that is equidistant from the two centrosome poles. This even alignment is due to the counterbalance of the pulling powers generated by the opposing kinetochore microtubules,[3] analogous to a tug-of-war between two people of equal strength, ending with the destruction of B cyclin.[4] In certain types of cells, chromosomes do not line up at the metaphase plate and instead move back and forth between the poles randomly, only roughly lining up along the middleline.[citation needed] Early events of metaphase can coincide with the later events of prometaphase, as chromosomes with connected kinetochores will start the events of metaphase individually before other chromosomes with unconnected kinetochores that are still lingering in the events of prometaphase.[citation needed]
One of the cell cycle checkpoints occurs during prometaphase and metaphase. Only after all chromosomes have become aligned at the metaphase plate, when every kinetochore is properly attached to a bundle of microtubules, does the cell enter anaphase. It is thought that unattached or improperly attached kinetochores generate a signal to prevent premature progression to anaphase, even if most of the kinetochores have been attached and most of the chromosomes have been aligned. Such a signal creates the mitotic spindle checkpoint. This would be accomplished by regulation of the anaphase-promoting complex, securin, and separase.
Contents
[hide]
1 Metaphase in cytogenetics and cancer studies
2 See also
3 References
4 External links
Metaphase in cytogenetics and cancer studies[edit]
Human metaphase chromosomes (normal male karyotype)
The analysis of metaphase chromosomes is one of the main tools of classical cytogenetics and cancer studies. Chromosomes are condensed (thickened) and highly coiled in metaphase, which makes them most suitable for visual analysis. Metaphase chromosomes make the classical picture of chromosomes (karyotype). For classical cytogenetic analyses, cells are grown in short term culture and arrested in metaphase using mitotic inhibitor. Further they are used for slide preparation and banding (staining) of chromosomes to be visualised under microscope to study structure and number of chromosomes (karyotype). Staining of the slides, often with Giemsa (G banding) or Quinacrine, produces a pattern of in total up to several hundred bands. Normal metaphase spreads are used in methods like FISH and as a hybridization matrix for comparative genomic hybridization (CGH) experiments.
Malignant cells from solid tumors or leukemia samples can also be used for cytogenetic analysis to generate metaphase preparations. Inspection of the stained metaphase chromosomes allows the determination of numerical and structural changes in the tumor cell genome, for example, losses of chromosomal segments or translocations, which may lead to chimeric oncogenes, such as bcr-abl in chronic myelogenous leukemia.
See also[edit]
Interphase
Prophase
Prometaphase
Anaphase
Telophase
References[edit]
Jump up ^ "Chromosome condensation through mitosis". Science Daily. Retrieved 12 June 2007.
Jump up ^ "Metaphase plate". Biology Dictionary. Biology Online. Retrieved 9 December 2012.
Jump up ^ "Metaphase". Nature Education. Retrieved 9 December 2012.
Jump up ^ "The Cell Cycle". Kimball's Biology Pages. Retrieved 9 December 2012.
External links[edit]
Media related to Metaphase at Wikimedia Commons
[hide]
v
t
e
Cell cycle proteins
Cyclin
A (A1, A2)
B (B1, B2, B3)
D (D1, D2, D3)
E (E1, E2)
CDK
1
2
3
4
5
6
7
8
9
10
CDK-activating kinase
CDK inhibitor
INK4a/ARF (p14arf/p16, p15, p18, p19)
cip/kip (p21, p27, p57)
P53 p63 p73 family
p53
p63
p73
Other
Cdc2
Cdc25
Cdc42
Cellular apoptosis susceptibility protein
E2F
Maturation promoting factor
Wee
Cullin (CUL7)
Phases and
checkpoints
Interphase
G1 phase
S phase
G2 phase
M phase
Mitosis (Preprophase
Prophase
Prometaphase
Metaphase
Anaphase
Telophase)
Cytokinesis
Cell cycle checkpoints
Restriction point
Spindle checkpoint
Postreplication checkpoint
Other cellular phases
Apoptosis
G0 phase
Meiosis
Retrieved from "https://en.wikipedia.org/w/index.php?title=Metaphase&oldid=815876458"
Categories:
Mitosis
Cell cycle
Hidden categories:
All articles with unsourced statements
Articles with unsourced statements from December 2012
Use dmy dates from April 2017
Navigation menu
Personal tools
Not logged in
Talk
Contributions
Create account
Log in
Namespaces
Article
Talk
Variants
Views
Read
Edit
View history
More
Search
Navigation
Main page
Contents
Featured content
Current events
Random article
Donate to Wikipedia
Wikipedia store
Interaction
Help
About Wikipedia
Community portal
Recent changes
Contact page
Tools
What links here
Related changes
Upload file
Special pages
Permanent link
Page information
Wikidata item
Cite this page
Print/export
Create a book
Download as PDF
Printable version
In other projects
Wikimedia Commons
Languages
Български
Bosanski
Català
Čeština
Deutsch
Español
فارسی
Français
Հայերեն
Hrvatski
Italiano
Қазақша
Kreyòl ayisyen
Lietuvių
Македонски
Polski
Português
Română
Русский
Српски / srpski
Türkçe
Українська
Edit links
This page was last edited on 17 December 2017, at 19:53.
Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.
Privacy policy
About Wikipedia
Disclaimers
Contact Wikipedia
Developers
Cookie statement
Mobile view
Enable previews

values: mw-page-base noprint

values: mw-head-base noprint

values: firstHeading firstHeading en

values: siteSub noprint

values: jump-to-nav mw-jump

value: img

attrs: href class

attrs: class style

value: sup

values:
/wiki/DNA_sequence
mw-redirect
DNA sequence

values: This claim needs references to reliable sources. (December 2012)

values:
noprint Inline-Template Template-Fact
white-space:nowrap;

values: Edit section: Metaphase in cytogenetics and cancer studies

values:
/wiki/Malignant_cell
mw-redirect
Malignant cell

values:
reflist mw-references-wrap
list-style-type: decimal;

values: Cyclin-dependent kinase inhibitor protein

values: nowraplinks collapsible autocollapse navbox-inner

values: Category:All articles with unsourced statements

values: Category:Articles with unsourced statements from December 2012

values: Discussion about edits from this IP address [ctrl-alt-n]

values: A list of edits made from this IP address [ctrl-alt-y]

values: You are encouraged to create an account and log in; however, it is not mandatory

values: You're encouraged to log in; however, it's not mandatory. [ctrl-alt-o]

values:
/wiki/Metaphase
View the content page [ctrl-alt-c]
c

values: Discussion about the content page [ctrl-alt-t]

values: p-namespaces navigation vectorTabs p-namespaces-label

values:
p-variants
navigation
vectorMenu emptyPortlet
p-variants-label

values: Past revisions of this page [ctrl-alt-h]

values: p-views navigation vectorTabs p-views-label

values:
p-cactions
navigation
vectorMenu emptyPortlet
p-cactions-label

values:
mw-wiki-logo
/wiki/Main_Page
Visit the main page

values:
/wiki/Main_Page
Visit the main page [ctrl-alt-z]
z

values: Featured content – the best of Wikipedia

values: Find background information on current events

values: Метафаза – Bulgarian

values:
https://ca.wikipedia.org/wiki/Metafase
Metafase – Catalan
ca
ca
interlanguage-link-target

values:
https://es.wikipedia.org/wiki/Metafase
Metafase – Spanish
es
es
interlanguage-link-target

values: متافاز – Persian

values: Մետաֆազ – Armenian

values:
https://hr.wikipedia.org/wiki/Metafaza
Metafaza – Croatian
hr
hr
interlanguage-link-target

values:
https://it.wikipedia.org/wiki/Metafase
Metafase – Italian
it
it
interlanguage-link-target

values: Метафаза – Kazakh

values:
https://ht.wikipedia.org/wiki/Metafaz
Metafaz – Haitian Creole
ht
ht
interlanguage-link-target

values:
https://pl.wikipedia.org/wiki/Metafaza
Metafaza – Polish
pl
pl
interlanguage-link-target

values: Метафаза – Russian

values: interlanguage-link interwiki-ru badge-Q17559452 badge-recommendedarticle

values: Метафаза – Serbian

values:
https://tr.wikipedia.org/wiki/Metafaz
Metafaz – Turkish
tr
tr
interlanguage-link-target

values: Метафаза – Ukrainian

values: /static/images/wikimedia-button-1.5x.png 1.5x, /static/images/wikimedia-button-2x.png 2x

values: /static/images/poweredby_mediawiki_132x47.png 1.5x, /static/images/poweredby_mediawiki_176x62.png 2x

values:
suggestions
display: none; font-size: 13px;

values: mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject page-Metaphase rootpage-Metaphase skin-vector action-view


text:
Quality of service
From Wikipedia, the free encyclopedia
Jump to: navigation, search
For the customer service-oriented term, see service 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. 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.
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. 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.
Quality of service is particularly important for the transport of traffic with special requirements. 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.
Contents
[hide]
1 Definitions
2 History
3 Qualities of traffic
4 Applications
5 Mechanisms
5.1 Over-provisioning
5.2 IP and Ethernet efforts
5.3 Protocols
6 End-to-end quality of service
7 Circumvention
8 Doubts about quality of service over IP
9 Mobile (cellular) QoS
10 Standards
11 Open source software
12 See also
13 References
14 Further reading
15 External links
Definitions[edit]
In the field of telephony, quality of service was defined by the ITU in 1994.[1] Quality of service comprises requirements on all the aspects of a connection, such as service response time, loss, signal-to-noise ratio, crosstalk, echo, interrupts, frequency response, loudness levels, and so on. 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.[2]
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. 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. For example, a required bit rate, delay, delay variation, packet loss or bit error rates may be guaranteed. Quality of service is important for real-time streaming multimedia applications such as voice over IP, multiplayer online games and IPTV, since these often require fixed bit rate and are delay sensitive. Quality of service is especially important in networks where the capacity is a limited resource, for example in cellular data communication.
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.
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 reduces or eliminates the need for QoS mechanisms.
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.[3] High QoS is often confused with a high level of performance, for example high bit rate, low latency and low bit error rate.
QoS is sometimes used in application layer services such as telephony and streaming video to describe a metric that reflects or predicts the subjectively experienced quality. In this context, QoS is the acceptable cumulative effect on subscriber satisfaction of all imperfections affecting the service. 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). See also Subjective video quality.
History[edit]
Conventional Internet routers and LAN switches operate on a best effort basis. This equipment is less expensive, less complex and faster and thus more popular than competing more complex technologies that provided QoS mechanisms. There were four “Type of service” bits and three “Precedence” bits provided in each IP packet header, but they were not generally respected. These bits were later re-defined as Differentiated services code points (DSCP).
With the advent of IPTV and IP telephony, QoS mechanisms are increasingly available to the end user.[citation needed]
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 these network technologies remaining in use today, this kind of network lost attention after the advent of Ethernet networks. Today Ethernet is, by far, the most popular layer 2 technology. Ethernet uses 802.1p to signal the priority of a frame.
Qualities of traffic[edit]
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.[4]
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:
Low throughput
Due to varying load from disparate 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.
Dropped packets
The routers might fail to deliver (drop) some packets if their data loads are corrupted, or the packets arrive when the router buffers are already full. The receiving application may ask for this information to be retransmitted, possibly causing severe delays in the overall transmission.
Errors
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.
Latency
It might take a long time for each packet to reach its destination, because it gets held up in long queues, or it 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.
Jitter
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.
Out-of-order delivery
When a collection of related packets is routed through a network, different packets may take different routes, each resulting in a different delay. The result is that the packets arrive in a different order than they were sent. This problem requires special additional protocols responsible for rearranging out-of-order packets to an isochronous state once they reach their destination. This is especially important for video and VoIP streams where quality is dramatically affected by both latency and lack of sequence.
Applications[edit]
A defined quality of service may be desired or required for certain types of network traffic, for example:
Streaming media specifically
Internet protocol television (IPTV)
Audio over Ethernet
Audio over IP
IP telephony also known as Voice over IP (VoIP)
Videoconferencing
Telepresence
Storage applications such as iSCSI and FCoE
Circuit Emulation Service
Safety-critical applications such as remote surgery where availability issues can be hazardous
Network operations support systems either for the network itself, or for customers' business critical needs
Online games where real-time lag can be a factor
Industrial control systems protocols such as Ethernet/IP which are used for real-time control of machinery
These types of service are called inelastic, meaning that they require a certain minimum bit rate 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.
Mechanisms[edit]
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.
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.
Over-provisioning[edit]
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. This approach is simple for networks with predictable peak loads. The performance is reasonable for many applications. This might include demanding applications that can compensate for variations in bandwidth and delay with large receive buffers, which is often possible for example in video streaming. Over-provisioning can be of limited use, however, in the face of transport protocols (such as TCP) that over time exponentially increase the amount of data placed on the network until all available bandwidth is consumed and packets are dropped. Such greedy protocols tend to increase latency and packet loss for all users.
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.[5]
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.
IP and Ethernet efforts[edit]
Unlike single-owner networks, the Internet is a series of exchange points interconnecting private networks.[6] 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.
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.
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.
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 (now renamed as the DS Byte) of the IP(v4) packet header.
Early work used the integrated services (IntServ) philosophy of reserving network resources. In this model, applications used the Resource reservation protocol (RSVP) to request and reserve resources through a network. While IntServ mechanisms do work, it was realized that in a broadband network typical of a larger service provider, Core routers would be required to accept, maintain, and tear down thousands or possibly tens of thousands of reservations. It was believed that this approach would not scale with the growth of the Internet, and in any event was antithetical to the notion of designing networks so that Core routers do little more than simply switch packets at the highest possible rates.
In response to these markings, routers and switches use various queuing strategies to tailor performance to requirements. At the IP layer, 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.
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.
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.
At the Media Access Control (MAC) layer, VLAN IEEE 802.1Q and IEEE 802.1p can be used to distinguish between Ethernet frames and classify them. Queueing theory models have been developed on performance analysis and QoS for MAC layer protocols.[7][8]
Cisco IOS NetFlow and the Cisco Class Based QoS (CBQoS) Management Information Base (MIB) are marketed by Cisco Systems. [9]
One compelling example of the need for QoS on the Internet relates to congestion collapse. The Internet relies on congestion avoidance protocols, as built into Transmission Control Protocol (TCP), to reduce traffic under conditions that would otherwise lead to "meltdown". QoS applications, such as VoIP and IPTV, require largely constant bitrates and low latency, therefore they cannot use TCP and cannot otherwise reduce their traffic rate to help prevent congestion. QoS contracts limit traffic that can be offered to the Internet and thereby enforce traffic shaping that can prevent it from becoming overloaded, and are hence an indispensable part of the Internet's ability to handle a mix of real-time and non-real-time traffic without meltdown.
Protocols[edit]
The type of service (ToS) field in the IP(v4) header (now superseded by DiffServ)
Differentiated services (DiffServ)
Integrated services (IntServ)
Resource Reservation Protocol (RSVP)
Multiprotocol Label Switching (MPLS) provides eight QoS classes[10]
RSVP-TE
Frame relay
X.25
Some ADSL modems
Asynchronous Transfer Mode (ATM)
IEEE 802.1p
IEEE 802.1Q
IEEE 802.11e
HomePNA Home networking over coax and phone wires
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".
Audio Video Bridging
End-to-end quality of service[edit]
End-to-end quality of service can require a method of coordinating resource allocation between one autonomous system and another. The Internet Engineering Task Force (IETF) defined the Resource Reservation Protocol (RSVP) for bandwidth reservation, as a proposed standard in 1997.[11] RSVP is an 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.[citation needed] The IETF also defined Next Steps in Signaling (NSIS)[12] with QoS signalling as a target. NSIS is a development and simplification of RSVP.
Research consortia such as "end-to-end quality of service support over heterogeneous networks" (EuQoS, from 2004 through 2007)[13] and fora such as the IPsphere Forum[14] 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. EuQoS conducted experiments to integrate Session Initiation Protocol, Next Steps in Signaling and IPsphere's SSS with an estimated cost of about 15.6 million Euro and published a book.[15][16]
A research project Multi Service Access Everywhere (MUSE) defined another QoS concept in a first phase from January 2004 through February 2006, and a second phase from January 2006 through 2007.[17][18][19] Another research project named PlaNetS was proposed for European funding circa 2005.[20] 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.[21] It included a "Quality of Service Theme" and published a book.[22][23] Another European project, called WIDENS (Wireless Deployable Network System) [24] proposed a bandwidth reservation approach for mobile wireless multirate adhoc networks.[25]
Circumvention[edit]
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.
Protocols like ICA and RDP may encapsulate other traffic (e.g. printing, video streaming) with varying requirements that can make optimization difficult.
Doubts about quality of service over IP[edit]
The Internet2 project found, in 2001, that the QoS protocols were probably not deployable inside its Abilene Network with equipment available at that time.[26] Equipment available at the time relied on software to implement QoS. The group also predicted that “logistical, financial, and organizational barriers will block the way toward any bandwidth guarantees” by protocol modifications aimed at QoS.[27] They believed that the economics would encourage network providers to deliberately erode the quality of best effort traffic as a way to push customers to higher priced QoS services. Instead they proposed over-provisioning of capacity as more cost-effective at the time.[26][27]
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.[28]
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.
Mobile (cellular) QoS[edit]
Main article: Mobile QoS
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.
Mobility adds complication to the QoS mechanisms, for several reasons:
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.
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.
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. crosstalk), blocking probability (the probability that the required level of QoS can not be offered) and scheduling starvation. These performance measures are affected by mechanisms such as mobility management, radio resource management, admission control, fair scheduling, channel-dependent scheduling etc.
Standards[edit]
Quality of service in the field of telephony, was first defined in 1994 in the ITU-T Recommendation E.800. This definition is very broad, listing 6 primary components: Support, Operability, Accessibility, Retainability, Integrity and Security.[1] A 1995 recommendation X.902 included a definition is the OSI reference model.[29] In 1998 the ITU published a document discussing QoS in the field of data networking. X.641 offers a means of developing or enhancing standards related to QoS and provide concepts and terminology that will assist in maintaining the consistency of related standards.[30]
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: Next Steps for the IP QoS Architecture, RFC 2990  , and IAB Concerns Regarding Congestion Control for Voice Traffic in the Internet, RFC 3714  .
The IETF has also published Configuration Guidelines for DiffServ Service Classes, RFC 4594  as an informative or "best practices" document about the practical aspects of designing a QoS solution for a DiffServ network. They try to identify which types of applications are commonly run over an IP network to group them into traffic classes, study what treatment do each of these classes need from the network, and suggest which of the QoS mechanisms commonly available in routers can be used to implement those treatments.
Open source software[edit]
Linux Advanced Routing & Traffic Control (from 2000 to 2005)[31]
Linux Bandwidth Arbitrator (2003 through 2005)[32]
Zero Shell[33]
mod_qos adding QoS to the Apache HTTP Server
See also[edit]
Application service architecture
Best-effort
BSSGP
Bufferbloat
Class of service
Deep packet inspection (DPI)
Grade of service (GoS)
LEDBAT
Low Latency Queuing (LLQ)
Mean opinion score (MOS)
Micro Transport Protocol
Network neutrality
QPPB
Quality of experience (QoE)
Series of tubes
Streaming media
Subjective video quality
Tiered Internet
Traffic classification
Traffic shaping
References[edit]
^ Jump up to: a b "E.800: Terms and definitions related to quality of service and network performance including dependability". ITU-T Recommendation. August 1994. Retrieved October 14, 2011. Updated September 2008 as Definitions of terms related to quality of service
Jump up ^ Teletraffic Engineering Handbook Archived January 11, 2007, at the Wayback Machine. ITU-T Study Group 2 (350 pages, 4·48MiB)(It uses abbreviation GoS instead of QoS)
Jump up ^ Menychtas Andreas (2009). "Real-time reconfiguration for guaranteeing QoS provisioning levels in Grid environments". Future Generation Computer Systems. 25: 779–784. doi:10.1016/j.future.2008.11.001.
Jump up ^ Peuhkuri M., IP Quality of Service, Helsinki University of Technology, Laboratory of Telecommunications Technology, 1999.
Jump up ^ Yuksel, M.; Ramakrishnan, K. K.; Kalyanaraman, S.; Houle, J. D.; Sadhvani, R. (2007). "Value of Supporting Class-of-Service in IP Backbones" (PDF). IEEE International Workshop on Quality of Service (IWQoS'07). Evanston, IL, USA: 109–112. doi:10.1109/IWQOS.2007.376555. ISBN 1-4244-1185-8.
Jump up ^ An Evening With Robert Kahn Archived December 19, 2008, at the Wayback Machine., from Computer History Museum, 9 Jan 2007
Jump up ^ Bianchi, Giuseppe (2000). "Performance analysis of the IEEE 802.11 distributed coordination function". IEEE Journal on Selected Areas in Communications. 18 (3): 535. doi:10.1109/49.840210.
Jump up ^ Shi, Zhefu; Beard, Cory; Mitchell, Ken (2009). "Analytical Models for Understanding Misbehavior and MAC Friendliness in CSMA Networks". Performance Evaluation. 66 (9–10): 469. doi:10.1016/j.peva.2009.02.002.
Jump up ^ Ben Erwin (December 16, 2008). "How To Manage QoS In Your Environment, Part 1 of 3". Network Performance Daily video. NetQoS. Retrieved October 15, 2011.
Jump up ^ "VoIP on MPLS". Search Unified Communications. Retrieved 12 March 2012.
Jump up ^ Bob Braden ed. L. Zhang, S. Berson, S. Herzog, S. Jamin (September 1997), Resource ReSerVation Protocol (RSVP), IETF, RFC 2205  CS1 maint: Multiple names: authors list (link)
Jump up ^ "Next Steps in Signaling" Charter
Jump up ^ "EuQoS - End-to-end Quality of Service support over heterogeneous networks". Project website. 2004–2006. Archived from the original on April 30, 2007. Retrieved October 12, 2011.
Jump up ^ IPSphere: Enabling Advanced Service Delivery Archived January 13, 2011, at the Wayback Machine.
Jump up ^ "End-to-end quality of service support over heterogeneous networks". Project description. European Community Research and Development Information Service. Retrieved October 12, 2011.
Jump up ^ Torsten Braun; Thomas Staub (2008). End-to-end quality of service over heterogeneous networks. Springer. ISBN 978-3-540-79119-5.
Jump up ^ "Multi Service Access Everywhere (MUSE)". Project website. Retrieved October 12, 2011.
Jump up ^ "Multi Service Access Everywhere". Project description. European Community Research and Development Information Service. Retrieved October 12, 2011.
Jump up ^ "Multi Service Access Everywhere". Project description. European Community Research and Development Information Service. Retrieved October 12, 2011.
Jump up ^ "PlaNetS QoS Solution". Project website. Archived from the original on November 12, 2009. Retrieved October 12, 2011.
Jump up ^ "4WARD: Architecture and design for the future Internet". Project description. European Community Research and Development Information Service. Retrieved October 15, 2011.
Jump up ^ "Going 4WARD" (PDF). Project newsletter. June 2010. Retrieved October 15, 2011.
Jump up ^ Luís M. Correia; Joao Schwarz (FRW) da Silva (January 30, 2011). Architecture and Design for the Future Internet: 4WARD EU Project. Springer. ISBN 978-90-481-9345-5.
Jump up ^ "Wireless Deployable Network System". Project description. European Union. Retrieved May 23, 2012.
Jump up ^ R. Guimaraes; L. Cerdà; J. M. Barcelo-Ordinas; J. Garcia-Vidal; M. Voorhaen; C. Blondia (March 2009). "Quality of Service through Bandwidth Reservation on Multirate Ad-doc Wireless Networks". Ad Hoc Networks. 7 (2): 388–400. doi:10.1016/j.adhoc.2008.04.002.
^ Jump up to: a b Benjamin Teitelbaum, Stanislav Shalunov (May 3, 2002). "Why Premium IP Service Has Not Deployed (and Probably Never Will)". Draft Informational Document. Internet2 QoS Working Group. Archived from the original on September 12, 2010. Retrieved October 15, 2011.
^ Jump up to: a b Andy Oram (June 11, 2002). "A Nice Way to Get Network Quality of Service?". Platform Independent column. O'Reilly. Archived from the original on September 12, 2010. Retrieved October 15, 2011.
Jump up ^ Gary Bachula (February 7, 2006). "Testimony of Gary R. Bachula, Vice President, Internet2" (PDF). pp. 2–3. Retrieved October 15, 2011.
Jump up ^ "X.902:Information technology – Open Distributed Processing – Reference model: Foundations". ITU-T Recommendation. November 1995. Retrieved October 14, 2011. Updated October 2009.
Jump up ^ "X.641: Information technology - Quality of service: framework". ITU-T Recommendation. December 1997.
Jump up ^ "Advanced Routing & Traffic Control HOWTO". August 21, 2005. Retrieved October 14, 2011.
Jump up ^ "Linux Bandwidth Arbitrator". APConnections. Retrieved October 14, 2011.
Jump up ^ Fulvio Ricciardi. "QoS and Traffic Shaping in Transparent Bridge mode". Router/Bridge Linux Firewall website. ZeroShell Net Services. Retrieved October 15, 2011.
Further reading[edit]
Deploying IP and MPLS QoS for Multiservice Networks: Theory and Practice by John Evans, Clarence Filsfils (Morgan Kaufmann, 2007, ISBN 0-12-370549-5)
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.
QoS Over Heterogeneous Networks by Mario Marchese (Wiley, 2007, ISBN 978-0-470-01752-4)
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.
Integrated Services in the Internet Architecture: an Overview, RFC 1633
An Architecture for Differentiated services, RFC 2475
RSVP-TE: Extensions to RSVP for LSP Tunnels, RFC 3209
External links[edit]
Listen to this article (info/dl)

This audio file was created from a revision of the article "Quality of service" dated 2008-07-18, and does not reflect subsequent edits to the article. (Audio help)
More spoken articles
Nate Hoy. "Implementing QoS". Vonage Forum. Retrieved October 14, 2011.
Cisco's Internetworking Technology Handbook
Henning Schulzrinne (January 9, 2008). "Network Quality of Service". Columbia University faculty website. Retrieved October 14, 2011.
"Quality of Service". Microsoft TechNet. March 31, 2011. Retrieved October 14, 2011.
"Web Camera QoS Analysis Tool". FishyCam. October 31, 2012. Retrieved November 16, 2012.
"Quality of Service (QoS) in High-Priority Applications" (PDF). Transition Networks. February 2003. Retrieved February 16, 2017.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Quality_of_service&oldid=831211959"
Categories:
Internet architecture
Network performance
Quality of service
Streaming
Services marketing
Telecommunications engineering
Teletraffic
Hidden categories:
Webarchive template wayback links
CS1 maint: Multiple names: authors list
All articles with unsourced statements
Articles with unsourced statements from May 2015
Articles with unsourced statements from October 2011
Spoken articles
Articles with hAudio microformats
Navigation menu
Personal tools
Not logged in
Talk
Contributions
Create account
Log in
Namespaces
Article
Talk
Variants
Views
Read
Edit
View history
More
Search
Navigation
Main page
Contents
Featured content
Current events
Random article
Donate to Wikipedia
Wikipedia store
Interaction
Help
About Wikipedia
Community portal
Recent changes
Contact page
Tools
What links here
Related changes
Upload file
Special pages
Permanent link
Page information
Wikidata item
Cite this page
Print/export
Create a book
Download as PDF
Printable version
Languages
العربية
Български
Català
Čeština
Dansk
Deutsch
Eesti
Ελληνικά
Español
Euskara
فارسی
Français
Galego
한국어
Հայերեն
हिन्दी
Bahasa Indonesia
Italiano
ಕನ್ನಡ
Lietuvių
Македонски
Nederlands
日本語
Norsk
Polski
Português
Română
Русский
Slovenčina
Suomi
Svenska
தமிழ்
ไทย
Türkçe
Українська
Tiếng Việt
中文
28 more
Edit links
This page was last edited on 19 March 2018, at 11:47.
Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.
Privacy policy
About Wikipedia
Disclaimers
Contact Wikipedia
Developers
Cookie statement
Mobile view
Enable previews

key: html

type: local

value: div

attrs: id class

values: mw-page-base noprint

values: mw-head-base noprint

value: a

attrs: alt src width height srcset data-file-width data-file-height

attrs: href title

attrs: class id

attrs: id class lang

values: firstHeading firstHeading en

values: siteSub noprint

values: jump-to-nav mw-jump

attrs: role class

values:
note
hatnote navigation-not-searchable

value: b

values:
/wiki/Computer_networking
mw-redirect
Computer networking

values:
/wiki/Flow_(computer_networking)
mw-redirect
Flow (computer networking)

values:
/wiki/Blocking_probability
mw-redirect
Blocking probability

values:
/wiki/Streaming_multimedia
mw-redirect
Streaming multimedia

values:
/wiki/Multiplayer_online_game
mw-redirect
Multiplayer online game

values:
/wiki/Overprovisioning_(networking)
mw-redirect
Overprovisioning (networking)

values:
/wiki/Streaming_video
mw-redirect
Streaming video

values:
/wiki/Perceptual_speech_quality_measure
mw-redirect
Perceptual speech quality measure

values:
/wiki/Internet_router
mw-redirect
Internet router

values:
/wiki/Best_effort
mw-redirect
Best effort

values:
/wiki/IPv4_Header
mw-redirect
IPv4 Header

values:
/wiki/IP_telephony
mw-redirect
IP telephony

values: This claim needs references to reliable sources. (May 2015)

values:
noprint Inline-Template Template-Fact
white-space:nowrap;

values:
/wiki/Frame_relay
mw-redirect
Frame relay

values:
/wiki/Asynchronous_transfer_mode
mw-redirect
Asynchronous transfer mode

values:
/wiki/Multiprotocol_label_switching
mw-redirect
Multiprotocol label switching

values:
/wiki/Packet-switched_network
mw-redirect
Packet-switched network

values:
/wiki/Internet_protocol_television
mw-redirect
Internet protocol television

values:
/wiki/Circuit_Emulation_Service
mw-redirect
Circuit Emulation Service

values:
/wiki/Operations_support_systems
mw-redirect
Operations support systems

values:
/wiki/Online_games
mw-redirect
Online games

values:
/wiki/Industrial_control_systems
mw-redirect
Industrial control systems

values:
/wiki/Unique_selling_point
mw-redirect
Unique selling point

values:
/wiki/Service_level_agreement
mw-redirect
Service level agreement

values:
/wiki/Scheduling_algorithm
mw-redirect
Scheduling algorithm

values:
/wiki/IPv4_header
mw-redirect
IPv4 header

values:
/wiki/Resource_reservation_protocol
mw-redirect
Resource reservation protocol

values:
/wiki/IEEE_802.1p
mw-redirect
IEEE 802.1p

values:
/wiki/Media_Access_Control
mw-redirect
Media Access Control

values:
/wiki/Congestion_collapse
mw-redirect
Congestion collapse

values:
/wiki/IEEE_802.11e
mw-redirect
IEEE 802.11e

values: Edit section: End-to-end quality of service

values: This claim needs references to reliable sources. (October 2011)

values:
/wiki/IPsphere_Forum
mw-redirect
IPsphere Forum

values: Service Structuring Stratum (page does not exist)

values:
/wiki/Electronic_commerce
mw-redirect
Electronic commerce

values: Edit section: Doubts about quality of service over IP

values: United States Senate Committee on Commerce, Science and Transportation

values:
/wiki/Network_Neutrality
mw-redirect
Network Neutrality

values:
/wiki/Circuit_switched
mw-redirect
Circuit switched

values:
/wiki/Scheduling_starvation
mw-redirect
Scheduling starvation

values:
/wiki/Fair_scheduling
mw-redirect
Fair scheduling

values:
/wiki/Channel-dependent_scheduling
mw-redirect
Channel-dependent scheduling

values:
/wiki/OSI_reference_model
mw-redirect
OSI reference model

values:
/wiki/Request_For_Comments
mw-redirect
Request For Comments

values:
nofollow
external text
//tools.ietf.org/html/rfc2474

attrs: alt src title width height srcset data-file-width data-file-height

values:
nofollow
external text
//tools.ietf.org/html/rfc2205

values:
nofollow
external text
//tools.ietf.org/html/rfc2990

values:
nofollow
external text
//tools.ietf.org/html/rfc3714

values:
nofollow
external text
//tools.ietf.org/html/rfc4594

values:
/wiki/Low_Latency_Queuing
mw-redirect
Low Latency Queuing

values:
/wiki/Network_neutrality
mw-redirect
Network neutrality

values:
/wiki/Tiered_Internet
mw-redirect
Tiered Internet

values: -moz-column-width: 20em; -webkit-column-width: 20em; column-width: 20em;

values:
nofollow
external text
http://www.itu.int/rec/T-REC-E.800/en

values:
nofollow
external text
//doi.org/10.1109%2FIWQOS.2007.376555

values:
nofollow
external text
//doi.org/10.1109%2F49.840210

values:
nofollow
external text
//doi.org/10.1016%2Fj.peva.2009.02.002

values: Category:CS1 maint: Multiple names: authors list

values:
nofollow
http://www.euqos.eu/
external text

values:
nofollow
http://www.tmforum.org/ipsphere/
external text

values:
nofollow
http://www.ist-muse.org/
external text

values:
nofollow
external text
//doi.org/10.1016%2Fj.adhoc.2008.04.002

values:
/wiki/Stanislav_Shalunov
mw-redirect
Stanislav Shalunov

values:
nofollow
external text
https://www.webcitation.org/5shCiXna8

values:
nofollow
external text
https://www.webcitation.org/5shCWW1GT

values:
nofollow
external text
http://www.itu.int/rec/T-REC-X.902/en

values:
nofollow
external text
http://www.itu.int/rec/T-REC-X.641/en

values:
nofollow
http://lartc.org/
external text

values:
nofollow
http://www.bandwidtharbitrator.com/
external text

values:
nofollow
http://www.zeroshell.net/eng/qos/
external text

values: -moz-column-width: 30em; -webkit-column-width: 30em; column-width: 30em; list-style-type: decimal;

values:
nofollow
external text
//tools.ietf.org/html/rfc1633

values:
nofollow
external text
//tools.ietf.org/html/rfc2475

values:
nofollow
external text
//tools.ietf.org/html/rfc3209

values: position: absolute; top: 0px; left: 100px; right: 0px; bottom: 0px; height: 0px; width: 0px;

values: left: 50%; top: 50%; margin-left: -35px; margin-top: -27.5px;

values:
mwPlayerContainer k-player videoHolder
width: 200px; position: relative;

values:
float: left; margin-left: 5px;
floatnone

values:
/wiki/Wikipedia:Media_help
mw-redirect
Wikipedia:Media help

values: font-size: xx-small; line-height: 1.6em; margin-left: 60px;

values:
nofollow
external text
http://vonage.nmhoy.net/qos.html

values:
nofollow
external text
http://fishycam.com

values: Category:Webarchive template wayback links

values: Category:All articles with unsourced statements

values: Category:Articles with unsourced statements from May 2015

values: Category:Articles with unsourced statements from October 2011

values: Category:Articles with hAudio microformats

values: Discussion about edits from this IP address [ctrl-alt-n]

values: A list of edits made from this IP address [ctrl-alt-y]

values: You are encouraged to create an account and log in; however, it is not mandatory

values: You're encouraged to log in; however, it's not mandatory. [ctrl-alt-o]

values:
/wiki/Quality_of_service
View the content page [ctrl-alt-c]
c

values: Discussion about the content page [ctrl-alt-t]

values: p-namespaces navigation vectorTabs p-namespaces-label

values:
p-variants
navigation
vectorMenu emptyPortlet
p-variants-label

values: Past revisions of this page [ctrl-alt-h]

values: p-views navigation vectorTabs p-views-label

values:
p-cactions
navigation
vectorMenu emptyPortlet
p-cactions-label

values:
/wiki/Special:Random
Load a random article [ctrl-alt-x]
x

values: portal navigation p-navigation p-navigation-label

values: Guidance on how to use and edit Wikipedia

values: About the project, what you can do, where to find things

values: A list of recent changes in the wiki [ctrl-alt-r]

values: portal navigation p-interaction p-interaction-label

values: List of all English Wikipedia pages containing links to this page [ctrl-alt-j]

values: Recent changes in pages linked from this page [ctrl-alt-k]

values:
/wiki/Wikipedia:File_Upload_Wizard
Upload files [ctrl-alt-u]
u

values: A list of all special pages [ctrl-alt-q]

values: Permanent link to this revision of the page

values: Link to connected data repository item [ctrl-alt-g]

values: Printable version of this page [ctrl-alt-p]

values: جودة الخدمة – Arabic

values:
interlanguage-link interwiki-bg
display: none;

values:
interlanguage-link interwiki-ca
display: none;

values:
interlanguage-link interwiki-cs
display: none;

values:
interlanguage-link interwiki-da
display: none;

values:
interlanguage-link interwiki-et
display: none;

values: Ποιότητα υπηρεσιών – Greek

values:
interlanguage-link interwiki-el
display: none;

values:
https://eu.wikipedia.org/wiki/QoS
QoS – Basque
eu
eu
interlanguage-link-target

values:
interlanguage-link interwiki-eu
display: none;

values: کیفیت خدمات – Persian

values:
interlanguage-link interwiki-fa
display: none;

values:
interlanguage-link interwiki-gl
display: none;

values:
https://ko.wikipedia.org/wiki/QoS
QoS – Korean
ko
ko
interlanguage-link-target

values:
interlanguage-link interwiki-ko
display: none;

values: Որակի ծառայություն (համակարգչային ցանց) – Armenian

values:
interlanguage-link interwiki-hy
display: none;

values: सेवा की गुणवत्ता – Hindi

values:
interlanguage-link interwiki-it
display: none;

values: ಸೇವೆಯ ಗುಣಮಟ್ಟ – Kannada

values:
interlanguage-link interwiki-kn
display: none;

values:
https://lt.wikipedia.org/wiki/QoS
QoS – Lithuanian
lt
lt
interlanguage-link-target

values:
interlanguage-link interwiki-lt
display: none;

values: Квалитет на услуга – Macedonian

values:
interlanguage-link interwiki-mk
display: none;

values:
interlanguage-link interwiki-nl
display: none;

values:
interlanguage-link interwiki-ja
display: none;

values:
interlanguage-link interwiki-no
display: none;

values:
interlanguage-link interwiki-pl
display: none;

values: Qualidade de serviço (telecomunicações) – Portuguese

values:
interlanguage-link interwiki-ro
display: none;

values:
https://ru.wikipedia.org/wiki/QoS
QoS – Russian
ru
ru
interlanguage-link-target

values:
interlanguage-link interwiki-sk
display: none;

values:
https://fi.wikipedia.org/wiki/QoS
QoS – Finnish
fi
fi
interlanguage-link-target

values:
interlanguage-link interwiki-fi
display: none;

values:
interlanguage-link interwiki-sv
display: none;

values: சேவைத் தரம் – Tamil

values:
interlanguage-link interwiki-ta
display: none;

values: คุณภาพของการให้บริการ – Thai

values:
interlanguage-link interwiki-th
display: none;

values:
interlanguage-link interwiki-tr
display: none;

values:
https://uk.wikipedia.org/wiki/QoS
QoS – Ukrainian
uk
uk
interlanguage-link-target

values:
interlanguage-link interwiki-uk
display: none;

values:
https://vi.wikipedia.org/wiki/QoS
QoS – Vietnamese
vi
vi
interlanguage-link-target

values:
interlanguage-link interwiki-vi
display: none;

values: All languages (initial selection from common choices by you and others)

values: mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject page-Quality_of_service rootpage-Quality_of_service skin-vector action-view