Slides for Chapter 3: Networking and Internetworking From Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edition 4, © Pearson Education 2005

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Figure 3.1 Network performance ExampleRangeBandwidth (Mbps) Latency (ms) Wired: LANEthernet1-2 kms WANIP routingworldwide MANATM250 kms InternetworkInternetworldwide Wireless: WPANBluetooth ( ) m WLAN WiFi (IEEE ) km WMAN WiMAX (802.16)550 km WWAN GSM, 3G phone netsworldwide

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Figure 3.2 Conceptual layering of protocol software Layer n Layer 2 Layer 1 Message sent Message received Communication medium SenderRecipient

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Figure 3.3 Encapsulation as it is applied in layered protocols

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Figure 3.4 Protocol layers in the ISO Open Systems Interconnection (OSI) model

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Figure 3.5 OSI protocol summary LayerDescriptionExamples ApplicationProtocols that are designed to meet the communication requirements of specific applications, often defining the interface to a service. HTTP, FTP,SMTP, CORBA IIOP PresentationProtocols at this level transmit data in a network representation that is independent of the representations used in individual computers, which may differ. Encryption is also performed in this layer, if required. Secure Sockets (SSL),CORBA Data Rep. SessionAt this level reliability and adaptation are performed, such as detection of failures and automatic recovery. Transport This is the lowest level at which messages (rather than packets ) are handled. Messages are addressed to communication ports attached to processes, Protocols in this layer may be connection-oriented or connectionless. TCP,UDP NetworkTransfers data packets between computers in a specific network. In a WAN or an internetwork this involves the generation of a route passing through routers. In a single LAN no routing is required. IP,ATM virtual circuits Data linkResponsible for transmission of packets between nodes that are directly connected by a physical link. In a WAN transmission is between pairs of routers or between routers and hosts. In a LAN it is between any pair of hosts. Ethernet MAC, ATM cell transfer, PPP PhysicalThe circuits and hardware that drive the network. It transmits sequences of binary data by analogue signalling, using amplitude or frequency modulation of electrical signals (on cable circuits), light signals (on fibre optic circuits) or other electromagnetic signals (on radio and microwave circuits). Ethernet base- band signalling,ISDN

OSI Protocol Summary Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 LayerDescriptionExamples ApplicationProtocols designed to meet the communication requirements of specific applications, defining the interface to the service HTTP, FTP, SMTP, IIOP PresentationProtocols to transmit data in a network representation that is independent of the representation in individual computers; big/little endian, encryption, compression, EBCDIC to ASCII TLS security, SessionReliability and adaptation are performed. Detection of failure and automatic recovery; checkpointing; tunneling; authentication; permissions; synchronization SSH, web conferencing TransportCommunication addresses and ports are attached; connection-oriented or connectionless; congestion and flow control; packet assembly ; ports TCP, UDP NetworkHost addressing; end-end delivery; packet forwarding; routingIPV4/IPV6; RIP DatalinkTransmission of packets from node to node; LAN: between hosts; WAN: between routers; parity error detection and correction: transmission error Ethernet MAC, PPP PhysicalThe circuits and the hardware that drive the network; bytes and bits of data transmission: electrical signals, optical signals, radio and microwave signals; signaling, circuit switching RS-232C,

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Figure 3.6 Internetwork layers

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Figure 3.7 Routing in a wide area network Hosts Links or local networks A DE B C Routers

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Figure 3.8 Routing tables for the network in Figure 3.7 Routings from DRoutings from E ToLinkCostToLinkCost A B C D E local A B C D E Routings from ARoutings from BRoutings from C ToLinkCostToLinkCostToLinkCost A B C D E local A B C D E A B C D E

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Figure 3.9 Pseudo-code for RIP routing algorithm (Bellman Ford) Send: Each t seconds or when Tl changes, send Tl on each non-faulty outgoing link. Receive: Whenever a routing table Tr is received on link n: for all rows Rr in Tr { if (Rr.link ≠ n) { Rr.cost = Rr.cost + 1; Rr.link = n; if (Rr.destination is not in Tl) add Rr to Tl; // add new destination to Tl else for all rows Rl in Tl { if (Rr.destination = Rl.destination and (Rr.cost < Rl.cost or Rl.link = n)) Rl = Rr; // Rr.cost < Rl.cost : remote node has better route // Rl.link = n : remote node is more authoritative }

Distance Vector Routing Algorithm: Bellman Ford zWidely used routing protocols in practice: NOVELL, Cisco, Appletalk zDV is distributed, iterative, asynchronous zRouters maintain distance tables; information in the tables are updated by exchanging information with neighboring nodes zRows represent nodes in the network; columns represents links at a given node and the cost; zEach row contains path to send the information and the distance value (hops, latency, packets etc.) Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005

Routing Case 1 Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Hosts Links or local networks A DE B C Routers F 7

Routing Case 2 Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Hosts Links or local networks A DE B C Routers F 7 8

Routing Case 3 Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Hosts Links or local networks A DE B C Routers F 7 8 4

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Figure 3.11 Tunnelling for IPv6 migration AB IPv6 IPv6 encapsulated in IPv4 packets Encapsulators IPv4 network

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Figure 3.12 TCP/IP layers Messages (UDP) or Streams (TCP) Application Transport Internet UDP or TCP packets IP datagrams Network-specific frames Message Layers Underlying network Network interface

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Figure 3.13 Encapsulation in a message transmitted via TCP over an Ethernet Application message TCP header IP header Ethernet header Ethernet frame port TCP IP

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Figure 3.14 The programmer's conceptual view of a TCP/IP Internet

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Figure 3.15 Internet address structure, showing field sizes in bits

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Figure 3.16 Decimal representation of Internet addresses octet 1octet 2octet 3 Class A: 1 to to to 254 Class B: 128 to 191 Class C: 192 to to 239 Class D (multicast): Network ID Host ID Multicast address 0 to to to 255 Multicast address 0 to to to 255 Class E (reserved): to to to to to Range of addresses

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Figure 3.17 IP packet layout

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Figure 3.19 IPv6 header layout Source address (128 bits) Destination address (128 bits) Version (4 bits)Traffic class (8 bits)Flow label (20 bits) Payload length (16 bits)Hop limit (8 bits)Next header (8 bits)

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Figure 3.25 Bluetooth frame structure SCO packets (e.g. for voice data) have a 240-bit payload containing 80 bits of data triplicated, filling exactly one timeslot. bits: Access codeHeader copy 1 Header copy 2 Header copy 3 Data for transmission bits: DestinationFlowAckSeqTypeHeader checksum Address within Piconet = ACL, SCO, poll, null Header

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Figure 3.26 ATM protocol layers

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Figure 3.27 ATM cell layout

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 4 © Pearson Education 2005 Figure 3.28 Switching virtual paths in an ATM network