18 - ATMTrouble compiling the project code on Ubuntu:Virtualization of networksATMAsynchronous Transfer Mode: ATMATM: network or link layer?ATM architectureATM Adaptation Layer (AAL)ATM Adaptation Layer (AAL) [more]ATM Layer: ATM cellATM cell headerATM Layer: Virtual CircuitsIP-Over-ATMSlide 14Slide 15Chapter 5: Summary5: DataLink Layer 5-118 - ATMTrouble compiling the project code on Ubuntu:If you get the error: h_addr not a member of struct hostent In the file /usr/include/netdb.h:struct hostent{ char *h_name; /* Official name of host. */char **h_aliases; /* Alias list. */ int h_addrtype; /* Host address type. */ int h_length; /* Length of address. */ char **h_addr_list; /* List of addresses from name server. */ #if defined __USE_MISC || defined __USE_GNU #define h_addr h_addr_list[0] /* Address, for backward compatibility.*/ #endif };99 Comment out the #if defined and #endif statements (highlighted in green) and re-compile the code.( You may have to use "sudo" to edit the file.)95: DataLink Layer 5-3Virtualization of networksVirtualization of resources: a powerful abstraction in systems engineering:layering of abstractions: don’t sweat the details of the lower layer, only deal with lower layers abstractlye.g. in a dial-up connection, the telephone network is employed to provide a PPP connection – the Internet virtualizes the telephone network and the PSTN is just a “wire”.Similarly, the Internet virtualizes the ATM network to a link that connects two Internet nodes.5: DataLink Layer 5-4ATM ATM separate network in its own right different service models, addressing, routing from Internetviewed by Internet as logical link connecting IP routersjust like dialup link is really part of separate network (telephone network)5: DataLink Layer 5-5Asynchronous Transfer Mode: ATM1990’s/00 standard for high-speed (155Mbps to 622 Mbps and higher) Broadband Integrated Service Digital Network architectureGoal: integrated, end-end transport to carry voice, video, datameeting timing/QoS requirements of voice, video (versus Internet best-effort model)“next generation” telephony: technical roots in telephone worldpacket-switching (fixed length packets, called “cells”) using virtual circuits5: DataLink Layer 5-6ATM: network or link layer?Vision: end-to-end transport: “ATM from desktop to desktop”ATM is a network technologyReality: used to connect IP backbone routers “IP over ATM”ATM as switched link layer, connecting IP routersATMnetworkIPnetwork5: DataLink Layer 5-7ATM architecture adaptation layer: only at edge of ATM networkdata segmentation/reassemblyroughly analogous to Internet transport layerATM layer: “network” layercell switching, routingphysical layer5: DataLink Layer 5-8ATM Adaptation Layer (AAL)ATM Adaptation Layer (AAL): “adapts” upper layers (IP or native ATM applications) to ATM layer belowAAL present only in end systems, not in switchesAAL layer segment (header/trailer fields, data) fragmented across multiple ATM cells analogy: TCP segment in many IP packets5: DataLink Layer 5-9ATM Adaptation Layer (AAL) [more]Different versions of AAL layers, depending on ATM service class:AAL1: for CBR (Constant Bit Rate) services, e.g. uncompressed videoAAL2: for VBR (Variable Bit Rate) services, e.g., MPEG videoAAL5: for data (eg, IP datagrams)ATM cell5: DataLink Layer 5-10ATM Layer: ATM cellService: transport cells across ATM networkanalogous to IP network layer 5-byte ATM cell header48-byte payloadWhy?: small payload -> short cell-creation delay for digitized voicehalfway between 32 and 64 (compromise!)Cell headerCell format5: DataLink Layer 5-11ATM cell headerVCI: virtual channel IDwill change from link to link thru netPT: Payload type (e.g. RM cell versus data cell) CLP: Cell Loss Priority bitCLP = 1 implies low priority cell, can be discarded if congestionHEC: Header Error Checksumcyclic redundancy check5: DataLink Layer 5-12ATM Layer: Virtual CircuitsVC transport: cells carried on VC from source to destcall setup, teardown for each call before data can floweach packet carries VC identifier (not destination ID)every switch on source-dest path maintain “state” for each passing connectionlink,switch resources (bandwidth, buffers) may be allocated to VC: to get circuit-like perf.Permanent VCs (PVCs)long lasting connectionstypically: “permanent” route between two IP routersSwitched VCs (SVC):dynamically set up on per-call basis5: DataLink Layer 5-13IP-Over-ATMClassic IP only 3 “networks” (e.g., LAN segments)MAC and IP addressesIP over ATM replace “network” (e.g., LAN segment) with ATM networkATM addresses, IP addressesATMnetworkEthernetLANsEthernetLANs5: DataLink Layer 5-14IP-Over-ATMAALATMphyphyEthIPATMphyATMphyapptransportIPAALATMphyapptransportIPEthphy5: DataLink Layer 5-15IP-Over-ATMIssues:IP datagrams into ATM AAL5 PDUsfrom IP addresses to ATM addressesjust like IP addresses to 802.3 MAC addresses!ATMnetworkEthernetLANs5: DataLink Layer 5-16Chapter 5: Summary principles behind data link layer services:error detection, correctionsharing a broadcast channel: multiple accesslink layer addressinginstantiation and implementation of various link layer technologiesEthernetswitched LANSPPPvirtualized networks as a link layer:
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