(Quality Of Service) A defined measure of performance in a data communications system. For example, to ensure that real-time voice and video are delivered without annoying blips, a traffic contract is negotiated between the customer and network provider that guarantees a minimum bandwidth along with the maximum delay that can be tolerated in milliseconds.
Because dedicated channels are set up between parties, the plain old telephone system (POTS) delivered the highest QoS for years. However, when data are broken into packets that travel through routers in a LAN or WAN, QoS mechanisms are used to give higher priority to real-time data, such as voice over IP (VoIP), than to non-real-time data, such as file downloads. Another option in packet switching is to overbuild the network, ensuring that it will accommodate all traffic fed to it. See packet switching.
ATM was one of the first packet technologies to build in modes of service. Today, everything is built around IP, and there are a variety of methods competing to provide QoS in IP networks (see TOS, RSVP, Diffserv and MPLS).
QoS Vs. CoS
QoS (quality of service) refers to the mechanisms in the network software that make the actual determination of which packets have priority (see packet scheduler). CoS (class of service) refers to feature sets, or groups of services, that are assigned to users based on company policy. If a feature set includes priority transmission, then CoS winds up being implemented in QoS functions within the routers and switches in the network. See class of service.
Circuits to Packets to Circuits?
Nothing provides better quality than a dedicated channel between two parties. Some say, in time, with ever increasing wavelength division multiplexing (WDM), there will be enough optical bandwidth to have an available circuit between every telephone or videophone in every home and office in the world, and we will wind up essentially with circuit switching again, although implemented differently.
In the meantime, the late 1990s saw a huge buildup of fiber backbones in the U.S., which resulted in a glut of capacity after the turn of the century. This fiber overbuild has enabled voice and video calls over the Internet (VoIP) to provide reasonably good quality even though there is no standard QoS mechanism built into all the Internet backbones. See infranet and QoE.
Because dedicated channels are set up between parties, the plain old telephone system (POTS) delivered the highest QoS for years. However, when data are broken into packets that travel through routers in a LAN or WAN, QoS mechanisms are used to give higher priority to real-time data, such as voice over IP (VoIP), than to non-real-time data, such as file downloads. Another option in packet switching is to overbuild the network, ensuring that it will accommodate all traffic fed to it. See packet switching.
ATM was one of the first packet technologies to build in modes of service. Today, everything is built around IP, and there are a variety of methods competing to provide QoS in IP networks (see TOS, RSVP, Diffserv and MPLS).
QoS Vs. CoS
QoS (quality of service) refers to the mechanisms in the network software that make the actual determination of which packets have priority (see packet scheduler). CoS (class of service) refers to feature sets, or groups of services, that are assigned to users based on company policy. If a feature set includes priority transmission, then CoS winds up being implemented in QoS functions within the routers and switches in the network. See class of service.
Circuits to Packets to Circuits?
Nothing provides better quality than a dedicated channel between two parties. Some say, in time, with ever increasing wavelength division multiplexing (WDM), there will be enough optical bandwidth to have an available circuit between every telephone or videophone in every home and office in the world, and we will wind up essentially with circuit switching again, although implemented differently.
In the meantime, the late 1990s saw a huge buildup of fiber backbones in the U.S., which resulted in a glut of capacity after the turn of the century. This fiber overbuild has enabled voice and video calls over the Internet (VoIP) to provide reasonably good quality even though there is no standard QoS mechanism built into all the Internet backbones. See infranet and QoE.
 | Reproduced with permission from Computer Desktop Encyclopedia. Copyright (c) 1981-2009 The Computer Language Company Inc. All rights reserved. |
Additional Resources
- Apple Airport Extreme Base Station (Winter 2009)
- Great Performance With Some AnnoyancesI got this wireless router because my D-Link one had become unreliable. I opened the box and this router is beautiful, packaged in typical Apple style, although it didn't setup in typical style, and in fact it was a nightmare to setup.This router doesn't use...
- Discussion threads 2009-10-28
- A Net Neutrality Solution: Opinions Wanted
- I’ve been thinking about Net Neutrality for some time and wanted to get your thoughts and feedback on a solution that seems, well, so simple and obvious that I can't believe nobody has proposed it. A bit of background before you dive-in. Before analyzing and tracking...
- Blog posts 2009-10-26
- Net neutrality: a faster Internet for all
- If I pay my ISP for fast speeds, I should get it.If I pay my ISP for fast speeds, I should get it.I do [b]not[/b] want my internet to slow down just because some person on the [b]other[/b] end didn't pay for priority traffic.Net Neutrality had to happen in the...
- Discussion threads 2009-10-23
- Dynamic SLA Template Adjustments Based on Service Property Monitoring
- Service Level Agreements SLAs are used to manifest guarantees about certain functional and non-functional aspects of service execution. Service providers are confronted with a hard problem when trying to estimate reasonable QoS levels and other default settings for SLA templates. The insufficient use of formal service behaviour descriptions, varying resource...
- White papers 2009-09-08
- WaterRoof 2.2 (Mac)
- WaterRoof is a firewall management frontend with bandwidth tuning, NAT setup, port redirection, dynamic rules tracking, predefined rule sets, wizard, logs, statistics and other features. With WaterRoof you can set up the IPFW built-in firewall easily and quickly. With the NAT Setup feature you can fine-tune your internet sharing for...
- Software downloads 2009-09-07
- Service Level Agreement in Cloud Computing
- Cloud computing that provides cheap and pay-as-you-go computing resource is rapidly gaining momentum as an alternative to traditional IT Infrastructure. As more and more consumers delegate their tasks to cloud providers, Service Level AgreementsSLA between consumers and providers emerge as a key aspect. Due to the dynamic nature of the...
- White papers 2009-09-05
- SOA vs. JBOWS: here's an analogy that delivers
- So, basically, QoS. NT
- Discussion threads 2009-09-03
- Collaborative QoS-Information Sharing for Mobile Service Users: A Web 2.0 Business Model Proposal
- Mobile Service Providers MoSPs emerge, propelled by ubiquitous availability of mobile devices and wireless communication infrastructures. MoSPs' customers satisfaction and consequently their revenues, largely depend on the Quality of Service QoS offered by Wireless Network Providers WNPs at a particular location and time of a mobile service usage. This paper...
- White papers 2009-09-03
- Access control Lists (ACLs)
- In this white paper, we'll take a look at access control lists ACLs, often referred to as access lists or ACLs (sometimes pronounced "ackels"). In Cisco IOS, ACLs are used for many things, including, but not limited to, filtering data packets firewalling, controlling Telnet or SSH access to a router...
- White papers 2009-08-21
- SIP Forum approves V1.0 of SIPConnect Technical Recommendation
- Unblock your broadband phone calls nowIf your Vonage or other broadband VOIP phone is blocked in yourcountry, you can try the VPN for VOIP adapter service fromhttp://www.vpn4sip.comBy utilizing a special model of VPN router, This service bridges yourVOIP calls through the SSL Based VPN connection, you will be able tomake...
- Discussion threads 2009-08-18
- D-Link Wireless N Router DIR-615 - wireless router
- D-Link DIR-615I've used the DIR-615 in my home for over a year with good results. The price was right, and I can conduct video conference calls with Vonei Meeting (http://www.vonei.com) from my laptop on the wireless connection. Just be sure to download the latest firmware which includes QOS....
- Discussion threads 2009-08-17
- BriefingsDirect analysts debate the 'imminent death' of enterprise IT as cloud models ascend
- who's going to maintain the workstationsyeah it's a cloud system, but the hardware at the desk still needs to be maintained. Waiting for your 3rd party IT people could waste valuable time in the office.RE: BriefingsDirect analysts debate the 'imminent death' of enterprise IT as cloud models ascendI think...
- Discussion threads 2009-08-10
- Overcoming IP Telephony Performance Issues in a Converged Network
- When implementing Voice over IP VoIP onto a data network, you must ensure that the equipment capable of handling the additional load, and, more importantly, that the traffic will be properly classified, marked, and prioritized for optimal performance. Voice traffic is highly intolerant to delay, jitter, and packet loss, so...
- White papers 2009-08-07
- Was 4chan block about censorship, security or net neutrality?
- Was 4chan block about censorship, security or net neutrality?tens of thousands of DoS attacks are blocked every dayDana, you need to get your facts straight. DailyKos isn't exactly an authority figure on this and he even admitted to jumping the gun on the story like so many other people.The...
- Discussion threads 2009-07-29
- SOAPSonar Personal Edition 4.5.5 (Windows)
- Free XML, SOAP, and REST based service testing. Functional, performance, compliance, and security testing modes. Full support for WSDL-based SOAP testing with comprehensive WSDL Schema parsing and SOAP message generation. Identity and security testing features including WS-Identity, WS-Security, SAML, WS-Trust, SSL. SOAPSonar is now HP Quality Center EMAP certified.Version 4.5.5...
- Software downloads 2009-07-28
- Dumb wireless pipe wars: Google Voice coming to BlackBerry, Android
- Dumb wireless pipe wars: Google Voice coming to BlackBerry, AndroidTelcos are traditional 'divide and conquer' enterprisesJust make out that the separate services are actually intrinsically different, and charge accordingly.Worked fine when there were separate wires, but digital exchanges in the 1970s were naturally integrating the actual data paths.Now it is...
- Discussion threads 2009-07-15
- Optimum Ultra: So how fast is it?
- Optimum Online's $99 per month Ultra DOCSIS 3.0 service is one of fastest residential broadband offerings available today. But is it really "Up to" 101Mbps as advertised? As I mentioned in a post last week about broadband service outages, Last Friday, I was...
- Blog posts 2009-07-07
- Will security paranoia kill wireless health IT?
- Will security paranoia kill wireless health IT?Guaranteed QoS?What's he smoking?The #1 cause of poor data transmission is distance from a base station, whether it be WiFi, cell tower, or anything else. The #2 and #3 causes are the same; it's not until you get to page 2 or page...
- Discussion threads 2009-07-02
- TechNet Webcast: Windows 7 Seamless Network Access (Level 300)
- The attendee of this webcast will discover how networking capabilities in Windows 7 can reduce IT costs, improve productivity, and make it easier to manage than other operating systems. The presenter of this webcast will discuss the challenges of managing a network and how Windows 7 network solutions address the...
- Webcasts 2009-07-01
- WiMAX Base Station Scheduling Algorithms
- This white paper discusses about the scheduling algorithms for Orthogonal Frequency Division Multiple Access/Time Division Multiple Access (OFDMA/TDMA) based systems, which extends the PF scheme to multiple service types with diverse QoS requirements. Worldwide Interoperability for Microwave Access WiMAX is one of the most important broadband wireless technologies and is...
- White papers 2009-07-01
Premier Vendor Content Whitepapers, webcasts & resources from our Power Center Sponsors
- Reduce risk. Reduce complexity. Increase reliability.
-
A simplified IT environment isn't just less complex. It's also more reliable. Standardize on a single Linux platform with SUSE Linux Enterprise from Novell, and get the world's most interoperable Linux
- Learn more >>
- New Online Dashboard for IT Leaders
-
Read about top issues IT decision-makers face every day, plus get cost-effective solutions to real-life IT problems.
- Learn more >>
- Save time with automated shipping solutions
-
The Business Essentials Guide provides you useful tools and templates to help grow your business and save you time with automated shipping solutions.
- Visit the UPS Business Essentials Guide
- Microsoft Dynamics CRM Online - Free Six-Month Trial for Eligible Organizations
-
Microsoft Dynamics CRM Online provides fast online access, simple contact management and better sales performance for a low monthly cost - the best value on the market today.
- Learn more about the free, six-month trial offer>>
Popular Sanity Saver Videos
