Seminar on ITU-T hot topics for Standardization (Mar del Plata, Argentina, 2 September 2009)Interoperability technical means, services, classes and parameters of QoS A. Koucheryavy, ZNIIS General Director Advisor, ITU-T SG11 Vice Chairman
Content • ITU-T activities • Testing methodology history • Technical means interoperability • Model Networks • The services interoperability • The QoS interoperability • DiffServ • IPTV traffic • Benchmarking • QoS classes • Conclusions
ITU-T activities Resolution 76 “Studies related to conformance and interoperability testing, assistance to developing countries, and a possible future ITU mark program” was approved at the World Telecommunication Standard Assembly (Johannesburg, 2008).
“The interoperability of international telecommunication networks was the main reason to create ITU in the year 1865 (International Telegraph Union), and that this remains one of the main goals in the ITU strategic plan”.
What is the interoperability today?
Recommendation Y.101 “Global Information Infrastructure terminology: Terms and definitions” Interoperability is the ability of two or more systems or applications to exchange information and to mutually use the information that has been exchanged”. This Recommendation was approved at March 2000. It’s so long ago from today point of view.
We will consider further interoperability issues for the technical means, services and QoS context on the base of the last searching and developing progress and Study Group 11 ITU-T activities. The main focus for interoperability issues will be interoperability supporting by testing procedures.
The NGN concept is the real implementation plan for network modernization today. The full NGN definition could be found in the Recommendation Y.2001. The NGN concept includes the some QoS guarantees levels in according with Y.1540 and Y.1541 and very widely services set, in principle unlimited. Both of them points request to consider interoperability as a complex definition, including technical means, services and QoS interoperability, not only systems or applications.
The testing methodology history. • 1995, ITU-T (X.290), ETSI (ETS 300406) – conformance testing based on the ISO/IEC 9646 and specific telecommunication criteria and features. • 1999, ETSI (TR 101667) – Network Integral (Interconnection) testing (end-to-end, node-to-node).
The conformance testing goal is the specification profiles verification. The network testing goal is the correct, integrity and reliability services for users. The table 1 ETR 101 667 defines the users of both methodologies. The conformance testing methodology users are the vendors at first place and Administrations and operators optionally, the network testing methodology users are the Administrations and operators only.
Technical means interoperability The methodology of the model network using for network testing was proposed at ITU-T in 2004 (Q.39xx series). The model network is the network, which simulates the capabilities similar to those available in present telecommunication networks, has a similar architecture and functionality and users, the same telecommunication technical means.
The NGN testing experience. ZNIIS Model Network (2004, Softswitch) 1016 tests – 8.1% unsuccessful tests Plug Test ETSI (Slovenia, 2008, IMS) 410 tests – 18% unsuccessful tests. (Joint ITU-T/ETSI meeting, Moscow, ZNIIS, 10 April, 2009).
The Q.39xx Recommendation list. Q.3900 – Model Network Architecture Q.3901 – NGN (Softswitches) Q.3903 – Data base Q.3904 – NGN (IMS) (draft) Q.3905 – IPTV Q.3906.1 – Broadband access (wired) (draft) Q.3906.2 - Broadband access (WiFi) (draft) Q.3906.3 - Broadband access (WiMax) (draft)
The services interoperability testing The ITU –T recommendations on the services interoperability testing are absent today. Furthermore, the service scenarios for important NGN services are absent too. It’s very complicated problem today, but during ITU-T study period 2009-2012 the key recommendations set for service interoperability testing should be developed.
The detailed requirements for the services implementation should be developed. It could be include: • service definition and features; • network capabilities; • network architecture and function elements; • access network types and user equipments; • service delivery scenarios; • call flows; • reference points and protocols; • service implementation on the non-IMS network; • interworking with others services.
The testing scenarios, list and types of tests for NGN TS1 basic call and supplementary services, NGN TS1 streaming services and NGN TS1 multimedia services should be developed as separately ITU-T Recommendations.
The Q.39xx recommendation list (services testing) Q.3915 – TS1 (draft) Q.3916 – Testing scenarios, list and types of tests for NGN (TS1) basic call and supplementary services, Q.3917 - Testing scenarios, list and types of tests for streaming services (TS1), Q.3918 - Testing scenarios, list and types of tests for multimedia services (TS1).
The QoS interoperability The many networks are realized NGN concept. At first, of course, it’s the basic IP network. Furthermore, it could be WiFi (based on Ethernet technology), IPTV and so on.
The some QoS mechanisms were developed for QoS supporting at IP-based networks. The recommendation Y.1291 which was approved in 2004 determine four standardized approaches for QoS supporting: Integrated services (IntServ), Differentiated services (DiffServ), MultiProtocol Label Switching (MPLS), IPCablecom Dynamic QoS.
DiffServ The service level agreement (SLA) concept and the wireless broadband access technologies development (WiFi and WiMax) are shown, that DiffServ mechanism could be using for QoS supporting in the heterogeneous NGN networks. If we can see the IEEE 802.11e or QoS requests at the pooling-based services for WiMax, we will found that the QoS classes based on DiffServ concept.
There are three PHB classes: • Assured Forwarding (AF PHB); • Expedited Forwarding (EF PHB); • Best Effort or Default PHB.
EF PHB is targeted to applications which require strict guarantees of end-to-end delay. The EF PHB applications request the QoS level, which compare with the QoS level for unloaded network.
AF PHB has been designed for a range applications which require different QoS guarantees. There are four classes of PHB identification codes within the AF PHB group. Within each class there are three distinct DiffServ Code Points (DSCP) with different packet drop precedence.
The mapping between Y.1541 QoS classes and DiffServ mechanism are determined in the recommendation Y.1291. The EF are corresponding with Y.1541 classes 0 and 1, AF – classes 2, 3 and 4 respectively, and Best Effort – class 5. The mapping between VLAN (Virtual LAN in accordance with IEEE 802.1) and DiffServ DSCP are recommended in the Y.2112.
IPTV traffic The traffic flows types are really complicated for NGN. They are self-similar as usually. The self-similar traffic generation at the model network is a real problem today. We will consider IPTV traffic further.
The IPTV traffic measurements was made at ZNIIS model network. The actual traffic of movies named Ohotnik, likely thriller performed on DVD was analyzed for differences times fragments and for differences aggregation period in processing of measuring data. The minimum observation movies fragment is the 60s. The fragment includes 6863 frames, each of frame has the length 1356 bytes
H=0.48 Autocorrelation function
The Q.39xx recommendations list(for QoS testing) Q.3919 – The types of traffic flows which should be generated for voice, data and video on the Model Network for testing QoS parameters. Q.3920 – The types and list of tests for QoS testing on Model networks for traffic-unloaded conditions. Q.3921 - The types and list of tests for QoS testing on Model networks for traffic-loaded conditions. Q.3922 - The types and list of tests for QoS testing for intra-domain connectivity. Q.3923 - The types and list of tests for QoS testing for inter-domain connectivity.
Benchmarking COM 11-C33-E, SG11 meeting, 19-23 January, 2009, Geneva. ETSI TS 186 008-1, October, 2007
Q. Bench–IMS–NGN-A Q. Bench–IMS–NGN-B Q. Bench–IMS–NGN-C Q. Perf-Bench-IMS IMS/NGN Performance Benchmark Part 1: Core Concepts IMS/NGN Performance Benchmark Part 2: Subsystem Configurations and Benchmarks IMS/NGN Performance Benchmark Part 3: Traffic Sets and Traffic Profiles IMS/NGN Performance Benchmark Part 4: Delay objectives for various IMS transactions Benchmarking Recommendations list
Q. Bench-PES NGN A Q. Bench-PES NGN B Q. Bench-PES NGN C PES Performance Benchmark Part 1: Core Concepts PES Performance Benchmark Part 2: Subsystem Configurations and Benchmarks PES Performance Benchmark Part 3: Traffic Sets and Traffic Profiles
QoS classes The six QoS classes from 0 to 5 are defined at the table 2/Y.1541 “Guidance for IP QoS classes” Recommendation Y.1541.
The “0” QoS class contents real-time, jitter sensitive, high interaction applications. It could be VoIP and VTC (Video Teleconference). The same applications (VoIP, VTC) is the base for ”1” QoS class, named “Real-time, jitter sensitive, interactive” as we see, the difference is only between “high interactive” and “interactive”.
Q. Perf-obj test VS IP Network Performance objectives Tests for IP-based Voice services The Q.39xx recommendation list (for VoIP testing)
Conclusions. • The main goal of testing today should be network testing (interoperability) for supporting the correct, integrity and reliability services for users. • This goal could be supported by Model network methodology. • The interoperability issues include the technical means, services, QoS classes and parameters. All of this features create the Global Interoperability, which could be tested on the Model network in complex.