Editing Quality of service (section)

===Over-provisioning===
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. This calculation may need to appreciate 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 in the face of transport protocols (such as [[Transmission Control Protocol|TCP]]) that over time 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.

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.

Commercial VoIP services are often competitive with traditional telephone service in terms of call quality even without QoS mechanisms 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.<ref>{{Cite book| first1 = M.| last1 = Yuksel| first2 = K. K.| last2 = Ramakrishnan| first3 = S.| last3 = Kalyanaraman| first4 = J. D.| last4 = Houle| first5 = R.| last5 = Sadhvani| date = 2007| title = 2007 Fifteenth IEEE International Workshop on Quality of Service| chapter = Value of Supporting Class-of-Service in IP Backbones| url = http://www.cse.unr.edu/~yuksem/my-papers/iwqos07.pdf| pages = 109–112| location = Evanston, IL, USA| doi = 10.1109/IWQOS.2007.376555| isbn = 978-1-4244-1185-6| citeseerx = 10.1.1.108.3494| s2cid = 10365270| access-date = 2009-01-24| archive-date = 2012-04-30| archive-url = https://web.archive.org/web/20120430131119/http://www.cse.unr.edu/~yuksem/my-papers/iwqos07.pdf| url-status = dead}}</ref>