BASICS OF IP TELEPHONY. Guidelines for calculation-graphic works 5В specialty Radio engineering, electronics and telecommunications

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1 Non-profit joint-stock company АУЭС ALMATY UNIVERSITY OF POWER ENGINEERING AND TELECOMMUNICATIONS The chair of infocommunicational technology BASICS OF IP TELEPHONY Guidelines for calculation-graphic works 5В specialty Radio engineering, electronics and telecommunications Almaty Summary plan 2015, pos. 126

2 Katipa Chezhimbayeva Sharafat Mirzakulova Vyacheslav Bublik BASICS OF IP - TELEPHONY Guidelines for calculation-graphic works 5В specialty Radio engineering, electronics and telecommunications Editor Kozlov V. S. Specialist for standardization Moldabekova N.K. Approved for publishing.. Format 60х84 1/16 Release 20 items Paper typographic 1 Value 1,3125 ed.-pub.p. Order Price 656 tenge Copy office of non-profit joint-stock company "Almaty university of power engineering and telecommunications" , Almaty, Baitursynov str., 126 5

3 1 Calculation-graphic work Compression by the method of reiterations lengths encoding Task 1.1: - using initial images from Appendix A, it is necessary to compress binarycoded (two-color) representation measuring 8 elements in a line and 8 elements in a column. Thus an empty cell designates white color, and cell with "X" sign designates a black; - input data set number of task equals student's number in teacher's students list. Scan a two-color image on lines (to two colors dark-and-light will correspond 0 and 1). As a result will get the binary vector of data Task 1.2: Describe the scenario (complete, registration, cancellation of registration, etc.) of communication between devices on IP-telephony network. Input data sets of tasks are described in Appendix B Guidelines for the task 1.1. The encoding of messages may be performed to reduce the amount of information and improve its transmission speed or reduce the bandwidth required for transmission. Such coding is called economical, or cost effective coding and data compression. The goal of data compression is to provide a compact representation of the data produced by the source, for their more efficient storage and transmission. Data compression system consists of a source encoder and decoder. The encoder converts the source data to compressed data, and a decoder for restoring the source data from the compressed data. The recovered data generated by the decoder can either be exactly the same as the original data source, or slightly different. We consider the compression method in which same sign sequences coded as its length in this paper. This method is quite effective in compression of binary data, such as black and white facsimile images, black and white images comprising a plurality of straight lines and uniform portions, circuits, etc. Length encoding is part of the well-known image compression algorithm JPEG (Joint Photographic Experts Group). The idea of data compression based on length coding repetitions is that instead of coding the actual data were coded numbers corresponding to long sections on which data is stored in fixed length value. Suppose we want to encode a binary (two-color) image size of 8 elements in the row and 8 elements in the column as shown in figure 1.1. After scanning the image along the lines get binary data vector X [1]. Х=( ) length of 64 bits (the speed of the source code is 1 bit per pixel). Isolate vector X areas on which data is stored have equal values, and define their length. The resulting sequence of lengths of positive integers corresponding to the original data vector X has the form r = (1, 9, 6, 6, 1, 9, 9, 1, 6, 1, 6, 9). Definite repeatability is noticeable in this sequence that can be coded in any static code (Table 1.1). 6

The result is a codewords sequence of length of 25 bits, that is, the resultant code rate R will be 25/64, or a little more than 0.39 bits per pixel.

4 Figure 1.1 A two-color image Table 1.1 Codewords The length of sequence Codeword In order to indicate that the encoded sequence starts with zero, character "0" should be added at the beginning of the codewords sequence. The result is a codewords sequence of length of 25 bits, that is, the resultant code rate R will be 25/64, or a little more than 0.39 bits per pixel. When compressing images larger and containing many repetitive elements the compression efficiency can be substantial. B(r)=( ) Guidelines for the task 1.2. IP-telephony - telephony over IP. IP-telephony means a set of communication protocols, technologies and methods, providing traditional telephony dialing, dialing, and two-way voice communication, as well as video calling over the Internet or any other IP-based networks. The signal is transmitted over a communication channel in digital form and is usually converted before transmission (compressed) in order to remove the excess information and reduce the load on the data network. Consider steps of the scenario of establishing a connection between two H.323 terminals (figure 1.2): - end point A (the caller) is connected to a terminal point B (the called party) and sends a initial request (Setup), which includes a call type (eg, audio signals only), numbers of called and calling parties; - endpoint B responds notification message (Alerting). Endpoint A shall take this message before elapsed time allotted for the Setup message; - when a user at the terminal station B answers the call (off-hook), the message Connect (Connect) is transferred to the end point A; 7

Figure 1.2 - Scenario of establishing a connection between terminals H.

5 Figure Scenario of establishing a connection between terminals H both terminals transmit information about their capabilities (media type, codec selection and information about multiplexing) reported Terminal Capability Set (checking of terminal capabilities); - each terminal responds Terminal Capability Set Ack (confirmation of terminal capabilities). If the remote endpoint does not have some features, a message will be sent TerminalCapabilitySetReject (deviation setting terminal capabilities), and terminals will continue to send these messages until they determine that the features are supported by both endpoints; - each terminal transmits H.245 OpenLogicalChannel (open logical channel), allowing you to open a logical channel to the remote endpoint for voice transmition; - in the case of readiness for acceptance each terminal transmits data OpenLogicalChannelAck (confirmation of the opening of the logical channel) to the 8

6 remote endpoint, specifying the port number on which the remote endpoint must transmit RTP data; - edpoints exchange information in RTP packets. During this exchange RTCP packets are transmitted for the quality control data; - when the endpoint A hangs up (hangs up), it shall send a message H.245 CloseLogicalChannel (close logical channel) for each channel open at a terminal point B; - endpoint B responds CloseLogicalChannelAck (confirmation of the closing of a logical channel); - endpoint A sends H.245 EndSessionCommand (logout), and closes the channel after receiving a similar message from the terminal point B; - send a message to both terminals H ReleaseComplete (complete exemption) for call signaling channel, which closes the channel and terminates the connection. 9

7 2 Calculation-graphic work Choice of the shortest way in a network using the Dijkstra s algorithm Task 2.1: - using basic data of topology of IP network (figure 2.1), it is necessary to choose the shortest way between nodes 1 and 5 using the Dijkstra s algorithm; - input data option number for task equals student's number in teacher's students list. Options are presented in Appendix C. Figure 2.1 Initial topology of network Task 2.2: - describe the operation of the network protocols; - input data option number for task equals student's number in teacher's students list. Options are presented in Appendix D Guidelines for the task 2.1. An Dijkstra s algorithm is the algorithm on columns, invented by the scientist Dijkstra in Netherlands in The algorithm finds the shortest distance from one of graph nodes to all other. An algorithm is widely used in programming and technologies. For example, it is used by routing protocols OSPF (Open Shortest Path First) and IS - IS (Intermediate System to Intermediate System). In this algorithm we will assign value to every node of graph, where a router is set - well-known minimum distance from one node to other. An algorithm works incrementally - on every step it visits one node and tries to decrease assigned values. Work of algorithm is completed, when all nodes are visited. We will consider an example implementation of algorithm on the example of telecommunications network topology, presented on a figure 2.2, consisting of four routers. There are channels between routers. Distance between routers shown near lines. 10

Figure 2.2 - Example of telecommunications network topology The mark of initial node of "1" relies equal to the zero, marks of other nodes are infinity.

8 Figure Example of telecommunications network topology The mark of initial node of "1" relies equal to the zero, marks of other nodes are infinity. What this means is that distances from "1" to other nodes are unknown (figure 2.3). Figure 2.3 Zero stage A zero stage is fixed on only purpose to specify an eventual site with a node "1", the mark of that is equal to zero. A node with a minimum mark is "1". Its neighbours are nodes "2" and "3" (figure 2.4). Figure First step First in turn neighbour of node "1" is node "2" because a distance to it is minimum (5). Thus a pathlength is equal to the sum of the shortest distance to the 11

9 node 1 and value assigned to node "1": 0+5=5. This value is less than currently assigned value of node 2 - infinity, therefore the new value of node "2" is equal to 5 (figure 2.5). Figure New value of the node "2" We will continue same operations with a node 3 (figure 2.6) Figure New value of the node "3" All neighbours of node "1" tested. We will blot it out from the graph to mark that this node is visited (figure 2.7). Figure 2.7 Node "1" removed 12

Again we find the nearest from the unvisited nodes. It is a node "2" with the current shortest path - 5 (figure 2.8). Figure 2.

10 Again we find the nearest from the unvisited nodes. It is a node "2" with the current shortest path - 5 (figure 2.8). Figure Visit of node "2" Again we try to decrease the marks of neighbours of the chosen node, trying to get in them through the node "2". Neighbours of node "2" are nodes "3" and "4". First in turn neighbour of node "2" is a node "1", but she is already visited, therefore with the node "1" nothing to do. A next neighbour is a node "3", because it has a minimum assigned value from the nodes (8) marked however visited. If to go to node "3" through a node "2", then length of such way will be equal to 16 (5+11). But currently assigned value of node "3" equals to 8 which is less than 16, currently assigned value does not change therefore. Figure Visit of node "2" (a mark of node "3" does not change) Another neighbour of node "2" is a node "4". Way to node "4" through a node "2" equals to 14. Because 14 is less than infinity (currently assigned to node "4"), we set the mark of node 4 equal to 14 (figure 2.10). All neighbours of node "2" tested. We will blot it out from the graph to mark that this node is visited (figure 2.11). We repeat choosing a node "3" (figure 2.12). As a result it will be canceled. We repeat for remaining node "4" (figure 2.13). Completion of implementation of algorithm takes place then, when all nodes are removed. As a result got shortest path from a node "1" to "2" equals to 5, to "3" - 8 and to "4"

Figure 2.10 New mark of node "4" Figure 2.

11 Figure 2.10 New mark of node "4" Figure Node "2" removed Figure 2.12 Node "3" removed Figure Node "4" removed 14

12 List of abbreviations PC - Personal computer ARP - Address Resolution Protocol DHCP - Dynamic Host Configuration Protocol DNS - Domain Name System FTP - File Transfer Protocol HTTP HyperText Transfer Protocol ICMP - Internet Control Message Protocol IGMP - Internet Group Management Protocol IRC - Internet Relay Chat IS-IS - Intermediate System to Intermediate System ISDN - Integrated Services Digital Network ISUP - ISDN User Part IP - Internet Protocol MGCP - Media Gateway Control Protocol MPLS multiprotocol label switching SSH Secure Shell RMON Remote Network MONitoring RTCP - RTP Control Protocol RTP - Real-Time Transport Protocol RIP - Routing Information Protocol RTSP Real Time Streaming Protocol RSVP Resource ReSerVation Protocol OSPF - Open Shortest Path First SCTP Stream Control Transmission Protocol SIP - Session Initiation Protocol SNMP Simple Network Management Protocol SMTP Simple Mail Transfer Protocol TCP - Transmission Control Protocol UDP - User Datagram Protocol VoIP Voice over IP 15

13 Appendix А Input data for task 1.1 Data set 1 Data set 2 Data set 3 X X X X X X X X X X X X X X X X X X X X X X Data set 4 Data set 5 Data set 6 X X X X X X X X X X X X X X X X X X X X X X Data set 7 Data set 8 Data set 9 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X Data set 10 Data set 11 Data set 12 X X X X X X X X X X X X X X X X X X X X X X X X 16

14 Continuation of appendix A Data set 13 Data set 14 Data set 15 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X Data set 16 Data set 17 Data set 18 X X X X X X X X X X X X X X X X X X X X X X Data set 19 Data set 20 Data set 21 X X X X Data set 22 Data set 23 Data set 24 X X X X 17

15 Continuation of appendix A Data set 25 Data set 26 Data set 27 X X X X X X X X X X X X X X X X X X X X Data set 28 Data set 29 Data set 30 X X 18

16 Appendix B Input data for task 1.2 Data set Procedures Automatic detection of Process of registration, Connection of terminals the gatekeeper (Н.323) registration cancellation without gatekeeper (Н.323) (Н.323) Data set Procedures Via the readdressing server (SIP) Via the proxy server (SIP) Between terminals H.323 Data set Procedures Management of access to network resources (Н.323) Determination of location of the equipment in a network (Н.323) Data set Procedures Release of a pass-band Detection and registration of the device Data set Procedures Poll of current state of the equipment Release of a pass-band Data set Procedures Establishment of connection on to protocols. Н.245 Termination of a communication session (Н.323) Data set Procedures Н.323 Connection of SIP from FEET Poll of current state of the equipment (Н.323) Establishment of an intrazone call Teams of management protocol. Н.245 Connection of SIP from FEET Н.323 separation of a session The elementary call by the SIP protocol Data set Procedures СТОП-IP-СТОП СТОП-VoIP VoIP- СТОП Data set Procedures Between the SIP hubs Between SIP nodes (ISAP) The redirection of inquiries in SIP Data set Procedures Establishment of connection (Н.323) Interactions of locks with agents (MGCP) Establishment of an interzone call (Н.323) 19

17 Appendix C Input data for task 2.1 Data set a b Distance between routers, km c d e f

18 Appendix D Input data for task 2.2 Data set Protocol IP IGMP RIP RSVP UDP Data set Protocol TCP DNS DHCP HTTP OSPF Data set Protocol ARP ICMP TELNET SNMP RMON Data set Protocol RTCP RTP SIP H323 MGCP Data set Protocol MPLS SCTP FTP HDLC SNMP Data set Protocol SSH RSVP SMTP IRC RTSP 21

19 References 1 Digital packet switching networks. -A Bektybaev T. Multilayer connection networks. -A., Goldstein AB IP - telephony. -M Goldstein, B.S., Pinchuk A., Sukhovitskaya A.L. IP-telephony. - Moscow: Radio svyaz Roslyakov A.V. IP - telephony. -M., Ivanov T.I. User terminals and computer telephony. -Moscow.: ECO- TRENDZ, with. 7 Goldstein A.B. CALL- centers and computer telephony. -SPb., Bektіbaev T.K. SA Abstract lecture. -A., Davidson D. Basics of voice data over IP. - M., p. 10 Electronic power Electronic power

20 AUTHORS: Chezhimbayeva K., Mirzakulova S., Bublik V. Basics of IP - telephony. Guidelines for calculation-graphic works for students of specialty 5В Radio engineering, electronics and telecommunications. - Almaty: AUPET, p. Calculation-graphic works on subject "Basics of IP - telephony" are presented. Tasks on compression by the method of reiterations lengths encoding and choice of the shortest way in a network using the Dijkstra s algorithm are included. Figures - 14, tables - 1, references- 7 sources. Reviewer: head of FL chair Kozlov V. Published according to the plan of non-profit joint-stock company "Almaty university of power engineering and telecommunications" for 2015 year NPJSC "Almaty university of power engineering and telecommunications", 2016 y. 23

Overview of the Session Initiation Protocol

Overview of the Session Initiation Protocol CHAPTER 1 This chapter provides an overview of SIP. It includes the following sections: Introduction to SIP, page 1-1 Components of SIP, page 1-2 How SIP Works, page 1-3 SIP Versus H.323, page 1-8 Introduction