Lic.(Tech.) Marko Luoma (1/39) Lic.(Tech.) Marko Luoma (2/39) Important dates and locations Lectures on Thursdays in S3 � S−38.180:Quality of Service in Internet � Start on September 18 th (today ;−) � Last lecture on October 23 rd Exercises on Wednesdays in Maari−C � Lecture I: History of Internet and QoS � Presence not required but highly recommended � Start on September 24 th � End on October 29 th 18.9.2003 � All exercise reports must be returned on October 29nd by 4pm, expect the 6 th exercise week later. We suggest you return the exercise reports before the next exercise begins. Final examination on November 17 th �
Lic.(Tech.) Marko Luoma (3/39) Lic.(Tech.) Marko Luoma (4/39) Material What is this course about The course textbook We are going to try and try and ty to get you to understand basics of � � � Differentiation and Quality of Service � Zheng Wang: "Internet Quality of Service: Architectures and Mechanisms " � ISBN: 1−55860−608−4 � What is the difference between these two � What have been standardized on these areas Lecture slides to support the lectures � � Why to choose this or that for particular application � these are NOT to be taken as a standalone material or as a replacement for the book � What is the big picture Additional reading � What are the small pieces that for the big picture � � Are there any sense to make these things � A selected set of related journal and conference papers and articles Exercise material to aid in completing the exercise and to provide background � Is there any sense to keep these lectures � information
Lic.(Tech.) Marko Luoma (5/39) Lic.(Tech.) Marko Luoma (6/39) Keep in mind Increasing the revenue Money talks and bullshit walks ISP want to increase their revenue � � � ISPs are there for the money � More money from the infrastructure � They don’t care about you � More customers to the current infrastructure � They don’t care about your applications � Lower quality for individual customer � Cost for the individual bit is lower � They don’t care what you are doing � Price for the individual bit is same � They care about your money � Therefore, � Differentiation of bits » They care your opinions � Same customer population with different categories » They care that you are satisfied � Different quality for individual customers � Cost per bit is higher � Price for individual bit is higher
Lic.(Tech.) Marko Luoma (7/39) Lic.(Tech.) Marko Luoma (8/39) Increasing the revenue Integration � Integration of networks Internet is becoming the next integration platfrom � � More services to the same network but with incremental charging � All services are going to be delivered by using it (at least it is going to be tried) � Cost per bit varies � Integration means that different media streams share common transmission � Price per bit varies system (IP) � Different medias have different requirements but there is only one IP
Lic.(Tech.) Marko Luoma (9/39) Lic.(Tech.) Marko Luoma (10/39) VoIP VoIP With real−time conversational services delay plays essential role Way they send their information is controlled by the fact that information is � � generated from sampling of analog information � 200ms one−way delay is absolute maximum for tolerable operation � PCM−codec uses 125us samling interval with 7/8 −bit samples � Also they expect to have their packets on steady intervals � VoIP software usually buffers these samples for 10−30ms to produce 1000km * 5us = 5ms decent packages (100−300 bytes) Loss 20000km * 5us = 100ms 9 r * 0.5ms/r = 4.5ms Loss Poor � Therefore there is a peak in 20 r * 0.5ms/r = 10ms VoIP = 20ms Poor 20% VoIP = 20ms � Time spectrum due to framing period Pros = 20 ms 20% Pros = 20 ms Potential %Loss = 1 Potential � Length spectrum due to fixed size of packet %Loss = 3 10% 10% Good Good 5% 5% Premium Premium 100ms 100ms 150ms 400ms Delay 150ms 400ms Delay
Lic.(Tech.) Marko Luoma (11/39) Lic.(Tech.) Marko Luoma (12/39) Data services Integration Data service usually are based on TCP−protocol, which by its nature tries to � Mixing these two service types in single network leads to certain problems � maximize network utilization while keeping packet losses on minimal level � Which is more important small delay (required by real−time connections) There is no clear expectation on service level as there are no easily measurable � or high utilization (starting point of TCP based dataservices) quantities � In packet level this shows out as differences � Other than throughput and latency � In sending process (frequency of packet sending To maximize utilization one expects to see as large packets are possible with as is very different) � high rate as possible � In quantity of information � Large number of this kind of processes lead to high burstiness as individual connections come and go
Lic.(Tech.) Marko Luoma (13/39) Lic.(Tech.) Marko Luoma (14/39) Integration Integration To overcome this we add quality and/or differentiation Dividing network into the fragments actually means that scheduling of network � � services is changed from First Come First Served (FCFS) to some other which � Network capacity is divided into fragments − one for each service quantity can cope with multiple parallel service requests � In connection based system this fragment is size of the connection and � Each request have weight that represents share of the network resources that number of parallel fragments is dependent on number of simultaneous are dedicated to individual request connections � In class based system this fragment is size of the aggregate and number of parallel fragments is dependent on number of service classes W 1 W 2 W 3 W 4
Lic.(Tech.) Marko Luoma (15/39) Lic.(Tech.) Marko Luoma (16/39) So this course is about QoS − differentiation How network resources can be connected to individual users, applications Small but remarkable difference: � � � Resources: � QoS � Network capacity , bits that flow through the links and routers � Pre negotiated numerical boundaries which are used for individual packets over the time lifetime of the connection � Buffer space , memory that is used to store contending packets � Differentiation � Pre negotiated numerical boundaries which are pursued over the lifetime of subscription
Lic.(Tech.) Marko Luoma (17/39) Lic.(Tech.) Marko Luoma (18/39) QoS Definitions (http://searchnetworking.techtarget.com/sDefi Goal is to device a service which could fulfill the demand � Using the Internet’s Resource � � nition/0,,sid7_gci213826,00.html) Reservation Protocol (RSVP), � Resources are connected to individual service requests On the Internet and in other packets passing through a gateway � � Numerical service descriptors of request are used as bases for resource networks, QoS (Quality of Service) host can be expedited based on reservation policy and reservation criteria is the idea that transmission rates, � New service requests are blocked if there are no resources available error rates, and other characteristics arranged in advance. Using ATM, which also lets a company or user can be measured, improved, and, to Request D some extent, guaranteed in advance. preselect a level of quality in terms Request C QoS is of particular concern for the of service, QoS can be measured and guaranteed in terms of the average continuous transmission of high− Request B bandwidth video and multimedia delay at a gateway, the variation in delay in a group of cells (cells are 53− information. Transmitting this kind Request A of content dependably is difficult in byte transmission units), cell losses, public networks using ordinary "best and the transmission error rate. effort" protocols.
Lic.(Tech.) Marko Luoma (19/39) Lic.(Tech.) Marko Luoma (20/39) Definitions Differentiation (http://www.webopedia.com/TERM/Q/QoS.h Current situation in Internet � � tml) � No differentiation Short for Quality of Service, a � � Equal opportunities −− equal misery networking term that specifies a � Depends on where are you looking ;−) guaranteed throughput level. One of the biggest advantages of ATM over competing technologies such as Frame Relay and Fast Ethernet, is that it supports QoS levels. This Service A Service B allows ATM providers to guarantee to their customers that end−to−end latency will not exceed a specified level.
Lic.(Tech.) Marko Luoma (21/39) Lic.(Tech.) Marko Luoma (22/39) Differentiation IP−service Differentiation means that resources are targeted to certain services or Internet service is connectionless datagram � � groups of users service � Overall resources do not increase � It roughly resembles normal snailmail � One gets better service � Each packet carries enough information to pass the network Throughput � Other get worse service � Each packet flows through independent � Analogy: Try to shake hands with people both side of you − which gets first route � Each packet experiences delay, Delay S e r loss and throughput which v i c e A dependent on network status and selected route S e r v i c e Loss B
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