1. CSci 8211 Lecture 2 David H.C. Du Department of Computer Science and Engineering

2. Overview of Four Subjects Storage Area Networks Optical Networks Streaming Video/Audio over Internet Wireless Networks Overlay Networks

3. What is storage area network? A storage area network is a network used to connected a bunch of storage devices (disks) and processors such that any processor can access any storage device directly. It is a separate network than the usual data network.

4. Requirements of Storage Area Network High Bandwidth Low latency High Throughput Potentially Multiple Channels Good Scalability

5. Examples of Storage Area Network Fiber Channel -Arbitrated Loop (FC-AL) Serial Storage Architecture (SSA) P1394 USB ServerNet InfiniBand iSCSI

6. Network I/O Characteristics Serial technology Open, unstructured, and unpredictable environment Used for transferring data plus time-sensitive voice/video Error-free delivery is a secondary consideration Heterogeneous at both the data link and protocol levels Serial technology Open, unstructured, and unpredictable environment Used for transferring data plus time-sensitive voice/video Error-free delivery is a secondary consideration Heterogeneous at both the data link and protocol levels Unlimited distance Unlimited connectivity Dynamic access and configuration Robust management tools Low speed Low reliability High overhead Software intensive PROS CONS

7. Channel I/O Characteristics High speed Low system overhead High reliability Rich command set PROS Distance limitations Limited connectivity Static configurations Few Management tools Typically run over a parallel bus. Closed, structured, and predictable environment Used for transferring data requiring error-free delivery Transfer delay is a secondary consideration Homogenous data link level protocol Typically run over a parallel bus. Closed, structured, and predictable environment Used for transferring data requiring error-free delivery Transfer delay is a secondary consideration Homogenous data link level protocol CONS

8. File-level and Block-level Comparison IP Front-End NetworkFC Back-End Network NFS, SMB, CIFS, NCP NAS SCSI, IDE, NTFS, FAT SAN File-level data access use application-to-file system protocols Block-level data access use file system-to-device protocols IP Network Fibre Channel

9. Key Drivers COMPUTING POWER Doubling every 18 months BANDWIDTH Doubling every 8-9 months STORAGE CAPACITY Doubling every 12 months Acceleration of higher bandwidth networking technologies

10. Related Issues Active Disks Active Networks Disk-Based XOR Object Oriented Devices SAN (Storage Area Network) NAS (Network Attached Storage)

11. Storage Model 1: Direct Access Storage High TCO All storage stranded behind server Proprietary access (vendor specific) Storage sharing creates CPU overhead Network burdened with disk I/O traffic Limited scalability and low performance Server

12. Storage Model 2: Fibre Channel SAN Replaces parallel SCSI transport SAN is DAS from servers’ perspective Optimized for movement of data from server to disk or tape Facilitates storage clustering & LAN-free backup Typically does not use LAN protocols, relies on serial SCSI (SCSI-3) SAN Server Interne t Intrane t

13. Storage Model 2: FC SAN Limitations Creates a 3 rd network (LAN, WAN, SAN) Pre-Gigabit Ethernet bandwidth assumptions Management nightmare Limited interoperability Minimal storage security Creates “SAN Islands” SAN Server Interne t Intrane t

14. Storage Model 3: IP-SAN Best features of Fibre Channel & IP networks Multiple server operating systems supported Maintain IT infrastructure, security & interoperability Ease of configuration and management Servers used optimally Support IP Quality of Service, Error detection & Prioritization StorageData IP VideoVoice LINUX WIN 2000 SN 5420 SUNNT 4.0 IP Network Fibre Channel

15. IP-SANs Scale Cost Effectively Preserve existing network infrastructure Gigabit Ethernet ports are 1/3 the cost of Fibre Channel Ports Decrease TCO Cost-effective Ethernet switching Fibre Channel

16. Storage Service Providers Today SSP Customer A’s Storage Customer BCustomer A Customer B’s Storage IP Network Fibre Channel Metro Area Network

17. Storage Service Providers with SN 5420 SN 5420 FCGbe SSP Customer BCustomer A IP IP Network Fibre Channel

18. Enterprise Network Today Disadvantages: Requires Fibre Channel in servers Servers are both application and I/O processors IP Network Fibre Channel

19. Enterprise Network with SN 5420 Advantages: Fibre Channel used for storage only IP accessable storage from anywhere Servers are dedicated to application processing Storage is pooled by linking SAN islands Eliminates need for Fibre Channel HBA SN 5420 FCGbe IP Network Fibre Channel

20. Implementation of SN 5420 IP Network What environments best suit SN 5420? Existing FC SANS Low port availability Under-utilized storage Midrange servers Non ‘performance critical’ applications  File servers  Print servers  Message servers  Web servers Fibre Channel SN 5420 FCGbe

21. InfiniBand System Area Network InfiniBand Architecture

22. Optical Network Extremely high bandwidth Emerging optical devices Security Fault-Tolerance Future Network Infrastructure

23. Emerging Optical Devices Frequency Changer Optical amplifier Tunable Transceiver Optical switch

24. Popular Optical Networks Optical Passive Star Coupler Optical Bus WDM Based Optical Wide Area Network IP over DWDM

25. Network Design Issues Communication Protocol Wavelength Assignment Wavelength Re-use Topology Embedding Fault-Tolerance Scalability Quality of Service over Optical Networks

26. Introduction (p,k)-ShuffleNet networks or Bus-mesh network This type of network is based on a physical optical passive star. Each station transmits (receives) via a fixed wavelength transmitter (receiver)

27. Introduction (cont.) Optical Passive Star Coupler

28. Introduction (cont.) Network topology representation proposed by Bus-Mesh Network Example: Connection topology of 12- station 4-wavelength Bush-Mesh Network. –Wavelengths are represented by a set of "buses". –Each station is represented by a node.

29. Connection topology of 12-station 4-wavelength Bush-Mesh Network

30. Introduction (cont.) Transmission cycle for the 12-station 4- wavelength Bus-Mesh Network

31. Receiving Graph Model Group the station that receiving on the same wavelength to a node. We call the group of w n the receiving node of w n.

32. The receiving graph representation of the 12-station, 4- wavelength Bus-Mesh Network

33. Receiving Graph Model (Cont.) Using different number of wavelengths to construct the Receiving Graph Model and their corresponding table of transmission cycle

35. Virtual Graph Embedding Design WTDM Networks –Since we have so many different topologies, how do we choose the most appropriate network topology in order to get the best performance? The building of Virtual Graph Embedding

36. Virtual Graph Embedding (Cont.)

38. The transmission cycle of the virtual graph embedding Each station is presented by the pair: (Stack ID, Xmit ID, Recv ID)

39. Virtual Graph Embedding (Cont.) In general, N = C    W –N: The number of stations –W: The number of exploited wavelengths –  : The number of stations (box-shaped nodes) in each virtual node. I.e. the degree of the virtual graph.) –C: The number of stacks

40. Routing Fast Packet Delivery Routing Algorithm –The basic idea of it is to first find the shortest length virtual path and then choose one of the corresponding paths with the shortest delay. Load Balancing Routing Algorithm –We always choose the node with least queuing to relay packets.

41. Optical network 2 3 1 5 4

42. Optical cross-connect: next generation Optical transport system (1.55  m) Optical transport system (1.55  m) Standard cross-office optics (1.3  m) Fibers In Fibers Out -Mux Add ports Drop ports... Transparency = node-bypass Optical-layer Cross-connect (Optical or Electronic Fabric)

43. Optical cross-connect: future generation?... Fibers In Fibers Out -Mux Add portsDrop ports Optical Space Switch 1 Optical Space Switch 2 Optical Space Switch 160...

44. All-optical networks All-optical network dream: –elimination of optical to electrical (O-E-O) conversion along connection’s route Advantages: –transparent services any protocol, transmission format –only two ends of lightpath need to know format –elimination of expensive transponders Disadvantages: –lack of wavelength conversion –analogue signal transmission impairments

45. Streaming Video/Audio over Internet Overall Internet Architecture Video/Audio Server Storage I/O and Network I/O Network Bandwidth and Buffer Allocation Quality of Service over Internet Network Support for Video/Audio Streaming

46. IP Network Architecture Content Deposit Area Wide-Area Backbone Web Proxy Server Streaming Video Server IP-based direct On-demand Content Broadcast Network Broadcast Network Intranet Clients Set-TopsTV StationsCorporate customer Sites (Content Aggregation) Diverse Content Providers IP Network Internet Clients Internet Browser Content Distribution Distributed Storage Wireless Devices Web Cache Server Streaming Video Server Web Cache Server Streaming Video Server Mobile Phone

47. Proxy Setting

48. Delivery Models Client-synchronization model: Proxy-synchronization model:

49. Background - Video Transmission Constraints

50. Background - CBR Transmission without Proxy

51. Video Streaming over Firewall and Router

52. Multi-Layered Video

53. Multi-Layer Encoding Lower quality playback Missing pieces of the active layers are pre-fetched on- demand Required pieces are identified by QA Results in smoothing Time L 0 L 1 L 2 L 3 L 4 Quality ( no. active layers ) Pre-fetched data Stored stream Played back stream

54. Pre-fetch higher layers on-demand Pre-fetched data is always cached Must pre-fetch a missing piece before its playback time Tradeoff Time L 0 L 1 L 2 L 3 L 4 Quality ( no. active layers ) Pre-fetched data Stored stream Played back Stream Multi-Layer Encoding Higher quality playback

55. Rate Adaptation Protocol (RAP) Time Rate Decision Freq Decision Function Increase Decrease Algorithm Why RAP? –Congestion Subnet Collapses –Inter-Protocol Fairness –High Network Utilization RAP implements –AIMD for fairness –Loss based rate control Issues Addressed –Decision Function –Increase/Decrease Algorithm –Decision Frequency

56. MPEG-4 Implementation and Applications

57. Streaming Video Over Internet Scalability Quality of Service Flow Management Differential Services Fault-Tolerance

58. Wireless Networks Wireless LAN Design Alternatives 802.11 Standard Bluetooth Technology Wireless IR Systems Wireless RF Systems Ad Hoc Networks IP/Wireless Wireless/Optical Connection

59. Wireless Challenges Low Power High Error Rate Multiple Standards High Mobility Flexible Applications Security Reliability

60. Design Choices Physical Layer: Infrared (IR) or Radio Frequency (RF)? –Both Systems are available today Radio Technology: Direct-Sequence or Frequency Hopping or NSS? Which frequency range to use? CSMA, TDMA or CDMA? Peer-Peer architecture or Base-Station approach?

61. Physical Layer Alternatives ParameterIRRFParameterIRRF cost<$10<$20CoverageSpotWide area RegulationNoneISMPerformanceModerateDepends on bandwidth InterferenceAmbient lightRadiatorsCoexistenceLimitedPossible

62. Radio Technology alternatives Spread Spectrum Technologies –Idea: make transmission looks like noise! –Frequency Hopping: different channels used at different times interference avoidance capacity, multiple network can coexist, higher capacity –Direct-Sequence: XOR information bit and pseudorandom chipping sequence lower cost, precise synchronization, Hard to pick orthogonal codes –ISM bands: 902-928M (cent), 2.4-2.4835G ($), 5.725-5.85G ($$$$) Non-Spread Spectrum Technologies –Require license, restriction on transportability, interference free (maybe) – no coexisting networks

63. Media Access Control & Network Topology Why MAC? –Contention/flow control CSMA/TDMA/CDMA/FDMA –All have commercial product –Examples: 802.11 – CSMA/CA & CDMA; Bluetooth – TDMA –CSMA: suitable for peer-to-peer architecture –TDMA: Base station/Remote station architecture Peer to Peer vs. Base Station –Base Station: no hidden terminals, higher transmission range, easy expansion, better approach to security –Peer to Peer – ad hoc networking (sensor networks, …)

64. 802.11 Standard Architectures Physical Layer –DSSS, FHSS, IR MAC layer –Point Coordination Function – PCF Base station polls terminals –Distributed Coordination Function – DCF(CSMA/CA) Binary exponential backoff RTS/CTS ACK per packet

65. Bluetooth Technology Goals: –Ad hoc wireless connectivity for everything –Original goal: low-cost replacement for the wire between cell phone and headset Results: two modes of operation –Point to Point (serial wire replacement) –Point to Multipoint (short range ad hoc networking) The convergence of communication and computing –Use mobiles to access data Small low-power radio in a chip supporting voice/data

66. Bluetooth Design Specification & Realities Design Specification –Frequency: 2.4G ISM band –Hybrid DS and fast FH (1600hops/s) –Piconet: 2 or more units sharing the same channel One master, others are slaves –Scatternet: two or more piconets interconnected –Range: 10 meters Realities: –Frequencies, cost, ad-hoc, security, … –Will be very cool when it arrives

67. Bluetooth Architectures – Piconet vs. Scatternet TDMA technique. Slot size: 0.625ms Master polls each slave Master-to-slave trans- mission starts from an even-numbered slots Slave-to-Master trans- mission starts from an odd-numbered slots Addresses 48bit IEEE 802 address Local active member addr.

68. Ad Hoc Networking with Bluetooth Personal Area Network (PAN, bubble): –Centered on a individual –Application scenarios: Internet access at any place, any moving speed Interconnect all of the person’s devices Many PANs form an ad hoc network – conferencing Two technologies compete for the PAN market – 802.11 vs. Bluetooth PAN Needs to support Data, voice & video in a mobility environment

69. Overlay Networks Internet is growing rapidly and can be considered as an integrated network How do search and access a document in Internet? How do provide a service in Internet?

70. Motivation How to find data in a distributed system? Internet Publisher Key=“LetItBe” Value=MP3 data Lookup(“LetItBe”) N1N1 N2N2 N3N3 N5N5 N4N4 Client ?

71. Applications Peer-to-peer systems Napster, Gnutella, Groove, FreeNet, … Large scale storage management systems Publius, OceanStore, PAST, Farsite, CFS... Mirroring (web caching) Any wide area name resolution system

72. Centralized Solution Internet Publisher Key=“LetItBe” Value=MP3 data Lookup(“LetItBe”) N1N1 N2N2 N3N3 N5N5 N4N4 Client DB Central server (Napster)

73. Distributed Solution (1) Worst case O(m) messages per lookup Internet Publisher Lookup(“LetItBe”) N1N1 N2N2 N3N3 N5N5 N4N4 Client Flooding (Gnutella, Morpheus, etc.)

74. Distributed Solution (2) Routed messages (Freenet, Tapestry, Chord, CAN, etc.) Internet Publisher Key=“LetItBe” Value=MP3 data Lookup(“LetItBe”) N1N1 N2N2 N3N3 N5N5 N4N4 Client

75. Evaluation Scalability –routing path length –per-node state Latency Load balancing Robustness –routing fault tolerance –data availability

76. Content Addressable Network Basic idea Internet scale hash table Interface –insert(key,value) –value = retrieve(key) Table partitioned among many individual node