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Multimedia Services in the Internet Dr. Dorgham Sisalem [email protected] These presentation materials describe Tekelec's present plans to develop and make available to its customers certain products, features and functionality. Tekelec is only obligated to provide those deliverables specifically included in a written agreement signed by Tekelec and customer. Goals • Overview of multimedia service • Understanding of multimedia services in the Internet • Understanding of the general pictures Transport protocols, signaling, traffic types, QoS • Practical experience with protocols and applications • Basic knowledge of the different involved protocols and concepts • We are not dealing with: Audio and video compression Web programming Image processing or speach recognition Audio and video hardware MMS or video over GSM Where to get the latest movies or how to copy a DVD Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding Structure • Pre-requirements Good understanding of IP networking principles • 2-Hour credit • Exam 10-12 10.07.07 • Office hours: After the lecture • Contact: [email protected] • Slides: http://www.iptel.org/~dor/uni.htm Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 3 References • www.ietf.org (RFCs and drafts) • www.iptel.org (SIP tutorial) • www.cs.columbia.edu/~hgs/internet XXXX • Stevens, „TCP/IP Illustarted, V1“ (basic protocols) • Ferguson, Huston, „Quality of Service“ (general QoS stuff) • Henry Sinnreich and Alan B. Johnston „Internet Communication Using SIP: Delivering VoIP and Multimedia Services with Session Initiation Protocol“ • Olivier Hersent, David Gurle, Jean-Pierre Petit,“IP Telephony“ • Huitema, „IPv6“ Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding Acknowledgements • Slides based on work of Henning Schulzrinne, Jim Kurose, Michael Smirnov, Georg Carle, Jiri Kuthan, Heikki Waris, Kevin Fall, Jim Chou, Thinh Nguyen, Vishal Misra, Steve Deering, Geert Heijenk, Ofer Hadar, John Floroiu, Nick McKeown, Eric D. Siegel, Ibrahim Matta, Steven Low, Vincent Roca, Nitin H. Vaidya, Charles Lang as well many other anonymous contributers. Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 5 Topics: Introduction • Introduction to Internet Very brief covering Difference between IP and PSTN Basic concepts Transport protocols: TCP, UDP, RTP Why use UDP for VoIP and TCP for signaling? What is the difference between RTP and RTCP You are expected to have visited the networking lecture of Prof. Wolisz Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 6 Topics: VoIP • What is VoIP • Signaling • Addressing • Intelligent services • Deployment problems: NAT, emergency • Integration with PSTN Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 7 Topics: VoIP What happens during this registration? Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 8 Topics: VoIP What does this address mean? How do we find the other side? How do we call a PSTN number? What happens when we press call? Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 9 VoIP in UMTS • What does IMS stand for? • Basic concepts of UMTS • What is the difference to normal VoIP? • How does it work? • Why a special version? Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 10 Problems of VoIP • Why doesn’t VoIP work over my DSL link What are the problems of network address tarnslators? How to deal with firewalls • Regulatory issues How can I call the 110? • Scalability How do I build a reliable carrier-grade VoIP infrastructure • Security What kind of attacks can we expect Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 11 Group Communication • What is the difference between broadcast and multicast • How does a conference bridge work • What solution is best fro which scenario? Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 12 Peer-To-Peer Networking • How do P-2-P solutions work? • What solutions exist? • What is Skype? • Basic concepts and approaches Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 13 Instant Messaging and Presence • What is presence and IM • Basic concepts and approaches • What solutions and technologies exist • What are the current standards • Relation to VoIP Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 14 Streaming • How are resources described? • What happens when we press play? (signaling) • What does it mean when it says “buffering” or ran out of buffer • What protocols exist and how do they work? Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 15 Public Switched Transmission Network PSTN These presentation materials describe Tekelec's present plans to develop and make available to its customers certain products, features and functionality. Tekelec is only obligated to provide those deliverables specifically included in a written agreement signed by Tekelec and customer. Public Switched Transport Network (PSTN) • Exists now for around 100 years • 800 M Subscribers • Optimized for Voice and Data (Fax) services • Guaranteed bandwidth share • In one country only a few exist usually a big one controlling the whole network • Cost of switching equipment high (A few millions for a carrier grade switching component • Signaling to session establishment and control based on SS7 • Hierarchical address structure (E.164) International Identity 2 digits National Identity 2-to-5 digits User Identity 11 to 5 digits Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding Subaddress Up to 40 digits ‘07 | 17 PSTN Architecture in Germany Fernnetz AVSt Auslandvermittlungsstelle Ca. 50 HVSt Hauptvermittlungsstelle Ca. 550 KVSt Knotenvermittlungsstelle Ortsnetz Ca. 500 OVSt Ortvermittlungsstelle Ca. 40 M Teilnehmer Ref. Prof. Dr.-Ing. Habil. Lutz Winkler, FH Mittweida Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 18 Routing in PSTN Ref. Prof. Dr.-Ing. Habil. Lutz Winkler, FH Mittweida Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 19 Switching in PSTN Capacity 100 99 calls active busy Ref. Prof. Dr.-Ing. Habil. Lutz Winkler, FH Mittweida Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 20 Resource Sharing (TDM) • Time division multiplexing (TDM) Allocate a time slot to a each call Resources are guaranteed May under utilize channel with idle senders Applicable only for a fixed number of flows Requires precise timers 10 kb/s 10 kb/s 10 kb/s 1 link, 30kb/s speed Multiplexer Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 21 Intelligent Service in PSTN Ref. Prof. Dr.-Ing. Habil. Lutz Winkler, FH Mittweida Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 22 Intelligent Service in PSTN • Service switching point (SSP): A switch enhanced with logic for identifying IN services • Service Transfer Point (STP): Interface of the switch to the IN environment • Service Control Point (SCP): Control the execution of the service • Service Management System (SMS): Control and manage the available services and provide the interface for adding new ones • Intelligent Peripheral: Additional components for providing certain services such as announcements • Feature Node: Execute services provided by private entities (similar to SCP) Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 23 Example of Free Call • Allow calls to a generic number: No costs for the caller, final location decided based on time of day …. Ref. Prof. Dr.-Ing. Habil. Lutz Winkler, FH Mittweida Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 24 Introduction to the Internet These presentation materials describe Tekelec's present plans to develop and make available to its customers certain products, features and functionality. Tekelec is only obligated to provide those deliverables specifically included in a written agreement signed by Tekelec and customer. General Words • Since more than 20 Years with the same technology (TCP/IP) • Moved from 4 sites in 1968 to around 200 M hosts today • Flat addressing and routing architecture • Based on packet switching • (the) Internet: “collection of networks and routers that spans x countries and uses the TCP/IP protocols to form a single, cooperative virtual network”. (Comer) • intranet: connection of different LANs within an organization Private may use leased lines usually small, but possibly hundreds of routers may be connected to the Internet (or not), often by firewall Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 26 Packet Switched Communication End Users End Users Router Data Packets (Voice, Video, Games, Signaling…) Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 27 What‘s a network? • Host: Communication end point (PC, PDA, cell phone, coffee machine ...) • Link: carry bits from one place to another (or maybe to many other places) • Switch/gateway/router: move bits between links, forming internetwork IP router receives a packet from one interface and sends it out over another 1 2 1 2 Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 28 What‘s a Protocol? • Protocol: rules by which active network elements communicate with each other • protocols = “algorithms + data structures” • formats of messages exchanged actions taken on receipt of messages how to handle errors hardware/operating-system independent real-life examples: rules for meetings conversational rules (interrupts, request for retransmission, ...) Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 29 Protocol Mechanisms (What Do Protocols Do for a Living?) • All or some of the following: addressing/naming: manage identifiers fragmentation: divide large message into smaller chunks to fit lower layer resequencing: reorder out-of-sequence messages error control: detection and correction of errors and losses retransmission; forward error correction flow control: avoid flooding/overwhelming of slower receiver congestion control: avoid flooding of slower network nodes/links Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 30 Architectural Requirements of the Internet • Generality Support ANY set of diverse applications, • Heterogeneity Interconnect ANY set of network technologies • Robustness More important than efficiency • Extensibility More important than efficiency • Scalability (A later discovery. How many ARPAnets could the world support? A few hundred, maybe… ?) Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 31 End-to-End Principle Foundation of the Internet architecture: • Dumb network, smart end systems (Exact opposite of telephone network!) • Dumb networks: require only least common service Datagram service: no connection state in routers Best effort: all packets treated equally. Can lose, duplicate, reorder packets. • Smart hosts: Maintain state to enhance service for applications. New applications can be introduced at end systems with no need for network upgrades. Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 32 Resource Sharing (Statistical) • Statistical multiplexing Traffic is sent on demand, so channel is fully utilized if there is traffic to send Any number of flows 5 kb/s 20 kb/s 5 kb/s 1 link, 30kb/s speed Multiplexer Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 33 Resource Sharing (Statistical) • Statistical multiplexing Resources are NOT guaranteed Need Mechanisms to prevent congestion and domination 5 kb/s 50 kb/s 5 kb/s Multiplexer Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding 1 links, 30kb/s speed, 50% Loss ‘07 | 34 Who runs the Internet? • “nobody” • standards: Internet Engineering Task Force (later. . . ) • names: Internic (US), RIPE (Europe), . . . • numbers: IANA (Internet Assigned Numbers Authority) • network: ISPs (Internet Service Providers), NAPs (Network Access Points), DFN, . . . • fibres: telephone companies (mostly) • content: thousands of companies, universities, individuals, . . . Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 35 How big is the Internet? • Many measures: networks (routed entities) domains, host names (but: several names per host!) directly (continuously) attached hosts (“ping’able”) IP-connected hosts (SLIP, PPP) firewalled hosts e-mail reachable Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 36 Host Count Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 37 What Networks are There? • Access (ISP): Carry data from users • Core Carry data from access • Network peering points Connect networks together • Some enterprises might be connected directly to core networks Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 38 An Example Network USER Backbone Local Loop Carrier Point of Presence Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 39 Network Access Point: Chicago NAP Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 40 Making the Standards • Internet Architecture Board: IAB architectural oversight elected by ISOC • Internet Engineering Steering Group (IESG) approves standards • Internet Society: ISOC Conferences “hosts” IANA • Internet Assigned Number Authority: IANA keeps track of numbers delegates Internet address assignment • Internet Engineering Task Force: IETF Define the problems and specify solutions to them Run by interested people (people should contribute in person and not as company representatives) Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 41 RFCs and Drafts • “Request for Comments”, since 1969 • most RFCs are not standards! • Internet drafts: working documents, but often used for prototypes • edited, but not refereed • numbered sequentially (Spetember 2002: more than 3600) • check the April 1 ones. . . (RFC 1149) • ftp://ds.internic.net/rfc Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 42 TCP/IP Stack TCP/IP Application Application VoIP Email .. Transport Transport TCP, UDP, SCTP Network Network Link Link Link Router Host Host Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding Network IP, IPv6 Ethernet Cable, UMTS ‘07 | 43 Internet Protocol • Deliver an IP packet from host to host(s) • Connectionless, unreliable No loss handling No flow or congestion control VoIP SMTP ICMP HTTP FTP RTP DNS UDP TCP IPv4/IPv6 PPP Ethernet GPRS SONET Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding AALx V.x ATM ‘07 | 44 Internet Names • Physical link address Ethernet, ATM ... Flat • IP address Identify an interface Topological • IP Name Identify the object to reach Hierarchical Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 45 IP Addresses • Identify an interface not host: A host can have more than 1 address • IP addresses are 32-bit numbers (4.3 billion of them!) • Divided into parts: (network prefix, host number) • 4 decimal numbers, called “dotted quad” • Each (decimal) number is one byte Example: 128.32.25.12 • Can generally be used in place of names Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 46 Internet Packets • A lot of headers describing the different layers Phy IP UDP/ TCP Body Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 47 IP Header • Version: 4 or 6 • Header length: number of 32 bit words of header • Type of Service: delay, throughput, reliability, monetary • Total length: length of packet in bytes • Identification: identify packet • Flag: MBZ: Do not fragment More fragments • Fragmentation offset: Distance from the first bit of the original packet • Time-to-Live: Avoid loops • Protocol: Which protocol is used (TCP, UDP, ICMP ..) • Header Checksum: Calculated over IP header • Source address: Address of sender • Destination address: Address of receiver Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 48 Special Addresses • Private addresses: Only of meaning inside an intranet 172.16 through 172.31 16 192.168.0 through 192.168.255 256 • Loopback: 127.0.0.1 (local interface) • Local broadcast: all 1 (receive by all members of link) • Multicast: 224.0.0.0 239.255.255.255 Do not describe a host or interface but a group of receivers • Reserved: 240.0.0.0 255.255.255.255 Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 49 IPv6: Why move to another protocol? • Lack of IP addresses Support for nearly endless range of addresses • Explosion of routing tables Allow for better aggregation and routing hierarchies • Better handling of options Reduce complexity of IP header • Better support for management and administration auto configuration and renumbering Support plug&play • Need for better support for mobile and secure communication Remove the need for network address translators Really? • Better support for QoS (which is not correct) Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 50 IPv4 vs. IPv6 Header • 8 fields, fixed 40 octet size • 14 fields, at least 20 octets • 128 bit addresses • 32 bit addresses • fragmentation only in endpoints, or lower layer • fragmented packet processing at every hop • header checksum recalculation at every hop • variable Options field for extra processing information • Usage of Path MTU discovery no checksums Already in lower layers • new 20 bit flow label field • options in Extension Headers Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 51 IP Names host name (has IP address) organization administering host Organization administering subnames to left organization type or country Oxany.fokus.fhg.de Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 52 Getting From A to B These presentation materials describe Tekelec's present plans to develop and make available to its customers certain products, features and functionality. Tekelec is only obligated to provide those deliverables specifically included in a written agreement signed by Tekelec and customer. Getting from A to B • Know name: need to know IP address Domain Name System (DNS) • Know IP address: need to know the way Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 54 Getting From A to B Name to IP Address These presentation materials describe Tekelec's present plans to develop and make available to its customers certain products, features and functionality. Tekelec is only obligated to provide those deliverables specifically included in a written agreement signed by Tekelec and customer. Domain Name System • The Domain Name System (DNS) is a distributed database that is used by TCP/IP applications to… map between hostnames and IP addresses, and to provide application routing information. • Distributed database: No single site on the Internet “knows it all.” Each site maintains its own database and runs a server that other systems on the Internet can query. • DNS is the client/server protocol. Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 56 Domains • Top level domains arpa domain Special domain for address-to-name mappings generic (organizational) domains 3-character domains (e.g. edu, com, org, …) Country (geographical) domains 2-character domains Found in ISO 3166 Some countries form second-level domains e.g.: .ac.uk is for academic institutions in the United Kingdom. New generic top level domains (gTLD) • .biz, .tv, .name, .aero ... Note: No single entity manages every node. Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 57 DNS hierarchical name space unnamed root top level domains de arpa us Maintained by DeNIC com edu gov wsu eecs gazoo math int mil net org •Node labels up to 63 characters. •Root node has null label. •Comparisons are case insensitive. •Domain name formed as follows: •start at node and work toward root •use a “dot” to separate labels Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 58 Resolvers and Name Servers • Applications (clients and servers) contact a DNS server by calling functions in a library known as a resolver. The resolver is accessed through the functions gethostbyname() and gethostbyaddr(). The resolver code is in a system library and is linked into the application. Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 59 DNS Operation • What does a server do when it does not have the requested information? Every name server must know how to contact the root name servers (via IP address). Name server contacts a root server Root servers know the name and IP address of all the second-level domains Each names server caches information from recent queries. Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 60 Practical • nslookup • http://www.internic.org Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 61 Routing Packets from A to B These presentation materials describe Tekelec's present plans to develop and make available to its customers certain products, features and functionality. Tekelec is only obligated to provide those deliverables specifically included in a written agreement signed by Tekelec and customer. Hierarchical PSTN Routing 030 040 050 Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding 060 ‘07 | 63 Distributed IP Routing 193.175.135.21 Core Access PictureTel Enterprise Core 195.37.78.225 Access Access Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 64 IP Routing • How to get from A to B? Different paths are possible!! Neither A nor B know the best path in advance!! • Goal: set routing tables for packet forwarding in hosts and routers, typically based on some optimality criterion. • Questions: who determines entries? based on what information (hops, delay, cost, ...) ? how often does it change (hop vs. delay)? where is routing information stored? algorithm used to compute routes? Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 65 IP Routing: Goals • scalability • “safe” interconnection of different organizations • adopt quickly to changes in topology • avoid routing loops or at least terminate them quickly • self-healing, robust • Distributed: No central component to determine the path • efficient: can’t use 90% of bandwidth for routing info • multiple metrics (QOS, price, politics, ...) not yet • routes should be (near) “optimal” • can’t have all hosts/networks in single table hierarchical Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 66 IP Routing • Every router needs to determine the next hop to which to send the data • Routing database: one entry for every possible destination in the system: Destination address: the IP address of the host or network; Next hop: the first router along the route to the destination; Interface: the physical network which must be used to reach the first hop Metric: a number, indicating the distance to the destination; Timer: the amount of time since the entry was last updated; Flags and other internal information. 1 2 1 2 Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 67 IP Routing • DB initialization: description of the entities that are directly connected; • DB update: messages from neighboring gateways. • Decision taken based on topology and updated continously No gurantee that two packets will follow the same path • ifconfig (ipconfig) • Netstat • http://www.traceroute.org/ Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 68 Intra-Domain Routing • Set the routes inside an autonomous system (AS) AS: a a collection of routers and system administered by one entity Has a AS number assigned by IANA • Different ASs might use different intra-domain routing schemes • Changes in one AS do not effect other domains • AS connects to another AS through one or more border routers Core Access Enterprise Core Access Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding Access ‘07 | 69 Contact Information Dr. Dorgham Sisalem Director, Strategic Architecture Tekelec Network Signaling Group Tel.:+49 30 32 51 32 14 E-mail: [email protected] Tekelec Confidential / For Discussion Purposes Only / Tekelec Confidential Non-Binding ‘07 | 70