Asynchronous Transfer Mode (ATM) - PowerPoint Presentation

1. Asynchronous Transfer Mode (ATM) NetworksAndreas ProdromouHMY 654 - Advanced Computer Networks1

2. The NetworkCell-switching and multiplexing technologyCombines the benefits of:Circuit switching (Virtual Circuits):Guaranteed capacity and constant transmission delayPacket switching:Flexibility and efficiencyCan be used for high-speed LANs, voice and video dataUtilizes fixed length cells to carry informationHMY 654 - Advanced Computer Networks2

3. The CellFixed size of 53 Bytes5 bytes for header48 bytes payloadAdvantages:Latency is significantly reducedEasier to switch data across multiple networksHMY 654 - Advanced Computer Networks3

4. The CellGeneric Flow Control (GFC):Provides local functionsTypically not usedVirtual Path Identifier (VPI):Identifies next destination (With VCI)Virtual Channel Identifier:Used with VPIPayload Type (PT):User/Control dataThe last cellHeader Error Control (HEC):Checksum of the headerCan correct single bit corruptionHMY 654 - Advanced Computer Networks4

5. DevicesATM networks are build around ATM SwitchesATM end-pointsAn ATM switch can be connected either to another switch or an end-pointHMY 654 - Advanced Computer Networks5

6. Switches and InterfacesATM switch supports two types of interfacesUser-Network Interface (UNI)Connects ATM end-point to a switchNetwork-Network Interface (NNI)Connects two switchesUNI and NNI can be divided in private and publicThird type: Broadband Inter-Carrier Interface (BICI)Connects two public switches from different service providersHMY 654 - Advanced Computer Networks6

7. Private and Public InterfacesUser-Network Interface (UNI)Private: Connects end-point to a private switchPublic: Connects end-point or private switch to a public switchNetwork-Network Interface (NNI)Private: Connects two switches within the same private organizationPublic: Connects two switches within the same public organizationHMY 654 - Advanced Computer Networks7

8. Private and Public InterfacesHMY 654 - Advanced Computer Networks8

9. Services and Virtual ConnectionsThree types of servicesPermanent Virtual Circuits (PVC)Switched Virtual Circuits (SVC)Connectionless serviceSVC is the most widely usedTwo types of connectionsVirtual Circuit (VC) Virtual Path (VP)There can be a number of VPs along a physical connectionThere can be a number of VCs within a VPHMY 654 - Advanced Computer Networks9

10. Virtual Circuits and PathsThere can be a number of VPs along a physical connectionThere can be a number of VCs within a VPHMY 654 - Advanced Computer Networks10

11. ATM Physical LayerBasic functions:Convert cells to bit streamsControl transmission and receipt of bitsPackage cells in appropriate types of frames for the mediumPhysical medium standards to carry ATM include:Synchronous Digital Hierarchy/Synchronous Optical Network (SDH/SONET)DS3/E3Over Multi-Mode Fiber (MMF) at 155 MbpsOver Shielded Twisted Pair (STP) at 155 Mbps HMY 654 - Advanced Computer Networks11

12. ATM Adaptation LayersAdaptation Layer converts user data into cell payloadsAAL 1Connection orientedSuitable for Constant Bit Rates (CBR) sourcesRequires timing synchronization (SONET)Voice and Video-ConferencingAAL 2Has timing requirementsVariable Bit Rate (VBR) traffic (Bursty)Supports Real-Time and Non-Real-Time VBRHMY 654 - Advanced Computer Networks12

13. ATM Adaptation LayersAAL 3/4Both connection-oriented and connectionless dataDesigned for network service providers to transmit SDMS packets (Switched Multimegabit Data Service)AAL 5Primary AAL for data a.k.a Simple and Efficient Adaptation Layer (SEAL)Supports CRC checkingLast cell is marked with one bitHMY 654 - Advanced Computer Networks13

14. ATM ConnectionsPoint-to-pointConnects two ATM end systemsUnidirectional (one-way)Point-to-multipointConnects one node (root) to multiple destination end-systems (leaves)Leaves cannot transmit to rootCell replication is done in the ATM switchesNo multipoint-to-multipoint communicationHMY 654 - Advanced Computer Networks14

15. Quality of ServiceATM Supports QoS guaranteesTraffic contract: Intended data flowPeak BandwidthAvg sustained bandwidthTraffic shapingConstrain data bursts (with queues)Limit peak data rateSmooth jittersTraffic policingThe switch measures the actual traffic and compares to the “contract”Notifies other switches that the package can be dropped in periods of congestionHMY 654 - Advanced Computer Networks15

16. Connection Establishment ProcessUses one-pass method of connection setupProcess:Source end system sends a connection-signaling requestRequest is propagated in the networkConnection request reaches destination which accepts or rejectsPrivate Network-Network Interface (PNNI)Routes connection requestsRouting is based on source and destination addresses, traffic and QoS parametersHMY 654 - Advanced Computer Networks16

17. Connection Establishment ProcessHMY 654 - Advanced Computer Networks17

18. Private Network-Network Interface (PNNI)ServicesATM topology discoveryCall establishmentEnables the switches to automatically discover the topology and characteristics of the linksOn significant events PNNI announces it to other switchesHMY 654 - Advanced Computer Networks18

19. LAN EmulationStandard defined by the ATM forumEmulates a LAN on top of ATM networkIEEE 802.3 EthernetIEEE 802.5 Token Ring LANFast Ethernet (100BaseT) and 802.12 (100VG-AnyLAN) can be mapped unchanged (same packet formats)Lane ComponentsLAN Emulation Client (LAC)LESBroadcast and Unknown Server (BUS)LAN Emulation Configuration Server (LECS)HMY 654 - Advanced Computer Networks19

20. LAN EmulationHMY 654 - Advanced Computer Networks20

21. Thank youQuestions?HMY 654 - Advanced Computer Networks21

22. Referenceshttp://docwiki.cisco.com/wiki/Asynchronous_Transfer_Mode_SwitchingIntroduction to Asynchronous Transfer Mode (ATM), N.GanesanHMY 654 - Advanced Computer Networks22