* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Intro to ATM - CS Course Webpages
Low Pin Count wikipedia , lookup
Airborne Networking wikipedia , lookup
Network tap wikipedia , lookup
Deep packet inspection wikipedia , lookup
Remote Desktop Services wikipedia , lookup
IEEE 802.1aq wikipedia , lookup
Internet protocol suite wikipedia , lookup
Computer network wikipedia , lookup
Cracking of wireless networks wikipedia , lookup
Point-to-Point Protocol over Ethernet wikipedia , lookup
Recursive InterNetwork Architecture (RINA) wikipedia , lookup
Wake-on-LAN wikipedia , lookup
Synchronous optical networking wikipedia , lookup
Real-Time Messaging Protocol wikipedia , lookup
Zero-configuration networking wikipedia , lookup
Multiprotocol Label Switching wikipedia , lookup
Intro to ATM • Asynchronous Transfer Mode • Text References – – – – Sect 2.6 Sect 3.6.3 Sect 5.6 Sect 6.5 ATM Background • Outgrowth of TELCO transition to integrated services • Only “real” >100Mbit standard • Offers multiservice (voice video data) potential • Switched architecture familiar to TELCOs, not to high speed data networks What is ATM? Application Presentation Note: Tanenbaum considers this more a network layer technology. Session Transport Network AA L Data/Link ATM Physical PL ATM - A layered standard AAL - ATM Adaptation Layer • Assembles and disassembles broadband servicesinto a stream of cells • Each cell has a header that contains routing information ATM - Asynchronous Transfer Mode • Switches the cells around the network based on the routing information in the header Physical Layer • Provides the physical transportation of cells across the network (Note: CCITT reference model, p. 63) ATM - A Switched Architecture • Cells (small, fixed length packets) are switched in a connection-oriented manner but not using circuits like today’s voice. Switch Edge Device Switch Edge Device What is ATM Switching? • Why small cells? – (32+64)/2=48 + 5 header bytes – Mixed Traffic • Packet (random)vs Circuit (TDM) Switching • Q.2931 – SVC, PVC Physical Layer Options • SONET (US)/ SDH (Europe) • SMDS • DQDB • Speeds from DS3 on up! (45Mbs to Gbps) • OC-3c => 155.52Mbps => 149.76Mbps ^ optical carrier ^ 3rd level in heirarchy ^ full duplex (two strands of fiber) • Also OC-12c (622Mbps), OC-48c (2048Mbps) [Look at the interesting way to frame cells] ATM Adaptation Layer (AAL) • Classes of Service: 1, 2, 3/4, 5 1: circuit emulation 2: variable bit rate service 3/4: connection oriented data service 5: connectionless data service • SAR - Segmentation and Reassembly • Convergence Sublayer the miscellaneous category ATM Cell • ATM cells are constant size packets of 53 bytes size. -- 48 bytes payload, 5 bytes header/overhead. VPI VPI (8 bits wide) VCI VCI VCI Type Res CLP HEC VPI - Virtual Path ID VCI - Virtual Channel ID Type - Payload type (internal) Res - reserved CLP- Cell loss priority HEC- Header Error Control VCI/VPI Operation • A Virtual Channel exists between two switching points VCI = a VCI = b • A Virtual Path contains 'bundles' of VCs ATM Switch Architecture • • • • Crossbar Banyan TDM busses Buffering – Input – Output – Both? ATM Protocols • UNI, NNI • Services • “LAN” Stuff ATM Services • • • • CBR VBR (RT, NRT) UBR ABR ATM Quality of Service • • • • • QoS: A contract Traffic Descriptors Cell Rate Options (pg 462) Traffic Shaping Traffic Policing ATM Congestion Control • • • • Admission Policy Reservation System Rate Based Control Other ATM Flow Control • The leaky bucket algorithm • CLP in ATM header • Frame Relay comparisons Routing •IISP (Interim Inter-switch Signaling Protocol) •PNNI (Private Network-Network Interface) •Phase 1 •Phase 2 IISP • Interim – Allowed multi-vendor interoperability before completion of NNI • Signaling • Routing via manually configured NSAP prefixes PNNI • Topology abstraction • Peer group(group of nodes) – One switch elected Peer Group Leader – All nodes in group have identical view of group • Hierarchy of logical groups – Up to 105 levels of hierarchy PNNI Routing A12 A11 A22 A21 A13 B3 A23 B1 A2 A1 NSAP Domain B2 B B25 A12 A117 A2 A11 A13 B View from A117 at A11 Sequence of Events • A117 -> B25 • Forward to switch (A11) – Switch knows topology of A1 group – B reachable by A2 - A2 reachable by either A12 or A13 • DTL (Designated Transit List) – [A12][A2][B] – [A22][A23][B] – [B2] ATM “LAN” Stuff • LAN == Link Layer Domain • ELANs & VLANs • LANE & MPOA – LECS, LES, BUS LANE v1 • LAN Emulation • No QoS (Quality of Service) Support • Uses AAL5 signaling optimized for data transport entire cell payload available for user data • LEC - LAN Emulation Client • LAN Emulation Service LECS - LAN Emulation Configuration Server LES - LAN Emulation Server BUS - Broadcast and Unknown Server • STP (Spanning Tree Protocol) supported LEC - LAN Emulation Client • Software process on any ATM-connected LAN switch, router, PC, or workstation • Layer 2 process • Prior knowledge of certain parameters LEC’s ATM address LAN type to be emulated maximum data frame size any route descriptors (for SR bridging) whether it is willing to proxy (respond to LE-ARP) LAN name - SNMPv2 display string LECS - LAN Emulation Configuration Server • One per administrative domain • Gives identity of ELAN (Emulated LAN) • Returns ATM address of LES, type of LAN emulated, and maximum PDU size of ELAN • Controls which physical LANs are combined to form VLANs (Virtual LAN) • LECS address known via ILMI or its well-known NSAP address LES- LAN Emulation Server • Adds LEC’s to ELAN • Assigns LECID to joining LEC • Table of address information of LEC MAC address proxy for MAC address Token Ring route descriptors • LECs can communicate directly with each other only when they are connected to the same LES • Multiple LESs on the same physical ATM LAN • Answers LE-ARP requests from LECs BUS- Broadcast and Unknown Server • During address resolution LEC forwards all frames to the BUS floods frames to all LECs after address resolved flush protocol used to guarantee order of cells • All multicast and broadcast traffic sent through BUS • Traffic limited to 10 frames/second • Intelligent BUS resolve destinations CLS- connectionless server LANE Setup Connections • All SVC (switched virtual circuits) • SVCs required: LECs and LECS LES and LECS Control Direct - LECs and LES pt-mpt Control Distribute - LES to LECs Multicast Send - LECs and BUS pt-mpt Multicast Forward - BUS to LECs Data Direct - LEC and LEC • PVC (permanent virtual circuit) possible to connect LEC and LECS Virtual Channel Connections LANE Server (LES) Control Direct VCC Broadcast and Unknown Server (BUS) Control Direct VCC LANE Client (LEC) Multicast Send VCC LANE Client (LEC) Multicast Send VCC LANE Client (LEC) Control Distribute VCC LANE Client (LEC) Multicast Forward VCC LAN Switch Data Direct VCC ATM Host Configuration Direct VCC Configuration Direct VCC LANE Configuration Server (LECS) ATM Host LAN Switch NHRP • • • • Next Hop Resolution Protocol Grew out of ATMARP Only IP Allows shortcut routes (pt-pt) direct VCCs across ATM network • Address resolution across multiple IP networks • If network unknown, request forwarded to other NHSs (Next-hop Server) NHS with knowledge will forward response to source router • Router must have ability to bypass default route RSVP • Resource Reservation Protocol • Provides QoS (Quality of Service) guarantees • Operates in simplex each direction has separate reservation maps well to ATM (two individual VCCs) • Built on IP, but no data transport built-in • Only if resources available and does not conflict with policy • Flowspec (bandwidth and delay) and filterspec (type of packets) transmitted downstream hop by hop MPOA • Multiprotocol over ATM • EDFG (Edge Device Functional Groups) existing LAN segments via LAN switches • AHFG (ATM-attached Host Functional Groups) ATM-connected host • Layer 3 • Only supports IP for now • Uses LANE for Layer 2 forwarding within a single Layer 3 subnet • Adaptation of NHRP to provide connectivity between hosts in different subnets MPOA Operation Competing Technologies • “Fast Ethernet” – 100BASE-TX, 100BASE-FX,100BASE-T4, 100BASE-VG • FDDI, FDDI- II • HPPI • Gigabit Ethernet (IEEE 802.3z) ATM Issues • SONET/SDH duplication of services • ATM overhead • ATM granularity and bandwidth management • ATM & connectionless service • End point synchronization • Flow Control !!! (bandwidth allocation, correlated traffic) • ATM Forum