Introduction Course Overview Lesson 1 IHA præsentation

Introduction & Course Overview Lesson 1 IHA præsentation 1

Teacher Martin Hjorth Stender Room: 426 mhs@iha. dk IHA præsentation 2

Course Overview • Generel communication in Protocol stacks • Peer-to-peer communication • Upper and lower layer • Syntaxes for describing PDU (messages exchanged between peer layers) • Protocol Design (Patterns) • Testing protocols IHA præsentation 3

Outline for today • Fundamentals of Computer Networks (Rep. ) • Circuit Switching vs. Packet Switching • Connection-Oriented vs. Connectionless • Communication Protocol Stacks in Action • Standard Organizations • • 3 GPP IETF Blue. Tooth Zigbee IHA præsentation 4

Outline for today • Fundamentals of protocols in a multi-service network • Layers of Communication • Horizontal Communication • Vertical Communication • Protocols in Real • • 3 GPP Long Term Evolution Zig. Bee ETSI Digital Enhanced Cordless Telecommunications TCP IHA præsentation 5

Fundamentals of Computer Networks IHA præsentation 6

Fundamentals of Computer Networks Two fundamental types of Network Switching: Circuit Switching DM F M/ D *T Packet Switching *Time-Division Multiplexing Frequency-Division Multiplexing IHA præsentation 7

Network core – Circuit switching Circuit Switching • Requires a Setup/release phase • for ressource reservation • Quaranteed end-to-end connection • Quaranteed constant rate (bandwidth) IHA præsentation 8

Fundamentals of Computer Networks 10 Mb/s Ethernet statistical multiplexing A B C 1. 5 Mb/s queue of packets waiting for output link Packet Switching D E • data stream divided into packets • packets share network resources • packets uses full link bandwidth and as needed • packets are stored & forwarded and queued. IHA præsentation 9

Packet- and Circuit switched Packet switching allows more users to use network! • 1 Mb/s link • each user: • 100 kb/s when “active” • active 10% of time • circuit-switching: N users 1 Mbps link • 10 users • packet switching: • with 35 users, probability > 10 active less than. 0004 = 0. 04% IHA præsentation 10

Connection-Oriented Service • Before two computers can communicate, they: • Establish a ’connection’ through the network, by • One computer requests a connection • Second computer accepts the connection • Data is transferred (full duplex…) • Connection is terminated IHA præsentation 11

Connectionless Service • When computer wants to send data, it: • Place data in an appropriate frame format • Attach the address of the destination computer • Pass the frame to the network for delivery IHA præsentation 12

Communication Protocol Stacks in Action GSM GPRS HTTP TCP/IP EDGE RTP/RTCP HSPA UMTS SIP FTP LTE UDP/IP DECT LTE-A SDP TETRA Blue. Tooth Zigbee IHA præsentation 13

Standard Organizations • 3 GPP • Specifies mobile communication protocols • GSM, GPRS, EDGE, UMTS, HSPA, LTE-A The 3 rd Generation Partnership Project (3 GPP) is a collaboration between groups of telecommunications associations, to make a globally applicable third generation (3 G) mobile phone system specification within the scope of the International Mobile Telecommunications-2000 project of the International Telecommunication Union (ITU). IHA præsentation 14

Standard Organizations • IETF • Specifies all Internet related protocols • TCP, UDP, IP, HTTP, FTP, SIP, SDP…… The Internet Engineering Task Force (IETF) develops and promotes Internet standards, cooperating closely with the W 3 C and ISO/IEC standard bodies and dealing in particular with standards of the TCP/IP and Internet protocol suite IHA præsentation 15

Standard Organizations • Blue. Tooth • Specifies (surprise) Blue. Tooth (core + profiles) IHA præsentation 16

Standard Organizations • Zigbee Alliance • Specifies (surprise) Zigbee (core + profiles) Zig. Bee is a specification for a suite of high level communication protocols using small, low-power digital radios based on the IEEE 802. 15. 4 -2003 standard for wireless personal area networks (WPANs), such as wireless headphones connecting with cell phones via short-range radio. IHA præsentation 17

Fundamentals of protocols in a multi-service network IHA præsentation 18

Layered Communication Computer Networks & Communication Systems Ressource Management Integrity protection - a need for structure? Flow control Authentication Modulation Channel coding Error concealment Interleaving Encryption Connection Management Addressing Error correction Re-transmission Identification Assembly Link adaptation Segmentation File transfer Error detection Web browsing IHA præsentation Location Tracking 19

Layered Communication Conclusion: - Computer Networks & Communication Systems are complicated processes. - To cope with this complexity we organize the systems into: LAYERS - A layer performs some of the functions necessary to achive communication between systems -Each layer built upon the layer below (except for the lowest layer) - The layers provide levels of abstraction IHA præsentation 20

Layered Communication The OSI Reference Model Intermediate Systems IHA præsentation 21

Layered Communication OSI Reference Model – Lower layers The physical layer Provides the mechanical, electrical and procedural means for transmitting bits over a communication medium. The data link layer Provides services for the transmission of data between directly connected systems in a communication network. The network layer Handles the routing of data through communication networks. IHA præsentation 22

Layered Communication OSI Reference Model – Upper layers The transport layer Provides reliable end-to-end services without being concerned about the route through communication networks. The Session layer provides facilities to organise and synchronise dialogues, i. e. communications that consist of several strands such as audio and video components. The Presentation layer deals with issues about how data is represented and ensures that the systems agree on how the information is transferred. The Application layer provides the means for application programs to access the communication system represented by the OSI reference model. For instance, the application layer can provide services for supporting file transfer and email. IHA præsentation 23

Layered Communication OSI Reference Model – Reflections 1. There should not be more layers than is necessary. 2. Boundaries should be located where they have proved successful in the past. 3. Boundaries should be located to minimise the interactions between layers. 4. Boundaries should be located where a standardised interface may be useful. 5. Separate layers should be created to perform functions that are associated with different technologies or levels of abstraction. 6. Functions associated with similar technology should be collected together in the same layers. IHA præsentation 24

Layered Communication Example – 4 layered protocol stack peer-to-peer communication IHA præsentation 25

Layered Communication Definition: - The rules for sending blocks of data (each known as a Protocol Data Unit (PDU)) from one node in a network to another node. A protocol specification defines the operation of the protocol and may also suggest how the protocol should be implemented. It consists of three parts: • Definition of Protocol Control Information (PCI) format which forms the PDU header • Definition of procedures for transmitting and receiving PDUs • Definition of services provided by the protocol layers IHA præsentation 26

Layered Communication Protocol Data Unit • Header (PCI - Protocol Control Information • Payload (SDU - Service Data Unit) • The protocol does not define or constrain the data carried in the payload part. • It does specify the format of the PCI, defining the fields which are present and the way in which the patterns of bits are to be interpreted IHA præsentation Packet Header Packet Payload 27

Layered Communication A protocol also defines the procedures which determine how the PDU will be processed at the transmit and receive nodes. The procedures specify the valid values for the PCI fields, and the action be taken upon reception of each PCI value (usually based on stored control information). Examples of procedures which are implemented in protocols include : • error recovery (e. g. the go-back-n procedure) • flow control • segmentation • service access point selection • connection management IHA præsentation 28

Horizontal Communication PDU PCI IHA præsentation 29

Vertical Communication Protocol Header Processing for Transmission by Layer N PDU PCI + PCI Layer N+1 Protocol Data Unit becomes a Layer N Service Data Unit SDU Layer N PDU PCI + SDU IHA præsentation 30

Vertical Communication Protocol Header Processing on Reception by Layer N PDU PCI + PCI Layer N+1 Protocol Data Unit is formed from the Layer N Service Data Unit SDU Layer N PDU PCI + SDU IHA præsentation 31

Vertical Communication Summary: - A layer encapsulates the SDU by adding a protocol header (PCI) - The combined PCI and SDU are known as a PDU - The PDU of Layer N forms the SDU of the layer below (N-1) Reflections: - Layer N does NOT know anything about the content of the PDU received How do we cope with a layer below that is providing multi-services? IHA præsentation 32

Vertical Communication How do communication takes place between two adjacent layers in the same system? OSI view of adjacent layer communication • Service Access Points (SAP) • Processes that communicates across the interface are called entities IHA præsentation 33

Vertical Communication The interaction between adjacent layers is expressed in terms of issuing and receiving primitives For each primitive up to four basic types are available • request – an entity invokes a service • indication – an entity is informed of an event • response – an entity reacts to an event • confirm – an entity is infromed of the result of an earlier request IHA præsentation 34

Vertical Communication IHA præsentation 35

Vertical Communication Example: DECT Call Control (NWK Layer) services: • Setup a phone call to remote (called party) • Alert service • Alert to the caller that the call is received (but not answered) • Connect to an incoming call • Release (terminate) a call IHA præsentation 36

Vertical Communication Example: DECT Call Control (NWK Layer) services: • Setup service • Setup. req, Setup. ind, Setup. res, Setup. cfm primitives • Alerting service • Alert. req, Alert. ind • Connect service • Connect. req, Connect. ind, Connect. res, Connect. cfm • Release service • Release. req, Release. ind, Release. res, Release. cfm IHA præsentation 37

Vertical Communication Example: DECT Call Control (NWK Layer) services: PDUs IHA præsentation 38

Vertical Communication Most primitives carries data Example DECT Setup. req: • Called party number • Calling party number • Transaction Identifier • Presentation Indication (may my number be displayed? ) IHA præsentation 39

Vertical Communication Most primitives carries data Example DECT Setup. req: • Called party number • Calling party number • Transaction Identifier • Presentation Indication (may my number be displayed? ) IHA præsentation 40

3 G – Access Stratum Example IHA præsentation 41