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Supporting Multimedia Communication over a Gigabit Ethernet Network VARUN PIUS RODRIGUES
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Need for Gigabit Networks Streaming Multimedia High performance distributed computing Virtual Reality Distance learning
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Development and Design Challenges Hardware Components: Gigabit Network Interface Card A buffered hub Gigabit routing switch File Server within LAN: Building pilot workgroups within LAN Integration of gigabit switches Design Challenges: Simplicity End-to-end solutions Extended to include emerging multimedia applications
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Design Features of Gigabit NIC 802.3 Frame compatibility Design challenge of the MAC ASIC to operate the GNIC Reducing host CPU utilization through Descriptor-based DMA
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IEEE 802.3z Standard Standard for MAC and PHY layers PHY Layer: Fiber: 1000 BASE-SX (multi-mode) and 1000 BASE-LX (single-mode) Copper-based: 1000 BASE-CX (twinax cable) MAC Layer: Identical to one defined for 10 Mbps and 100Mbps Ethernet Fields: DA, SA, LEN, DATA, FCS
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Designing GNIC Architecture Consideration: 64-bit 66 MHz GNIC-II Theoretical bandwidth: 4 Gbps vs 1 Gbps Practical bandwidth: 3 Gbps vs 800 Mbps Consists of: Application-specific Integrated Circuit (ASIC) Packet buffer memory Serializer/Deserializer chip Physical layer components
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ASIC Consists of: PCI Pair of DMA for controllers: for Rx and Tx Pair of FIFO connected to external FIFO interface GNIC Reducing CPU utilization: Accesses host memory directly through Descriptor-based DMA Transfer Chaining: transferring arbitrary nos of packets from host memory to GNIC Adaptability of interrupt rate of host to network load
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Design Features of Buffered Gigabit Hub Full-duplex: for eliminating CSMA/CD collision Congestion Control: to avoid frame dropping Round-Robin scheduling: to prevent “packet clumping”
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Performance issues with CSMA/CD Performance highly dependent on ratio of propagation delay to average packet transmission time Two ways to solve it: Increase minimum packet length Decrease length Length increased through virtual collisions
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Full Duplex Repeater Achieves switching and shared design concepts for switch-like performance while maintaining the cost of shared hub Provides maximum throughput, collisionless forwarding, and congestion control Logical flow of frames: Input -> Forwarding path -> Output Input: Passes though buffer PHY and MAC before being queued in buffer; congestion control informs end system to slow down incase capacity of buffer is about to be reached Forwarding path: Implements round robin scheduling to determine which port will send data Output: includes a buffer, MAC and PHY with congestion notification
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Design Features of Gigabit Routing Switch Architecture issues Parallel access shared memory architecture Priority Queue Design
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Architecture of Gigabit Routing Switch PE-4884 Consists of 12 channel cards, 1 EMM card for the chassis to function and 1 EMM card management, policy and routing table redundancy Channel cards: Supports connectivity to Ethernet, fast Ethernet, FDDI etc Sending and receiving data through physical interfaces and system packet memory Performing routing and switching address lookups Enforcing layer 4 policies; collecting management statistics, etc Every channel card connected to central memory through 2 full-duplex gigabit channels Contd…
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Architecture of Gigabit Routing Switch PE-4884 Memory Architecture: Uses parallel memory architecture for high speed performance Limitations of cross-bar architecture: Port-based memory Head-of-line blocking Difficult to provide QoS support Shared memory bus architecture overcomes these limitations Packet flow: Address Resolution Logic ASIC on channel card evaluates the destination address ARL signals memory control cards that a packet must be sent to which port Frame Management
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Supporting Distributed Multimedia Applications Challenges in On-Demand Video: Large data size Real-time constraint Supporting concurrent accesses Consideration for connection setup: Implementation of RSVP scheme New emerging standards such as IEEE 802.1p and 802.1Q Integrated solutions with policy-based QoS
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Experimental Results Two major goals: To test how a gigabit LAN performed in the basic metrics of throughput To examine how concurrent video delivery is supported over gigabit LAN Experiments designed to determine bottlenecks in current system and identify bounds on performance End-to-end performance is evaluated
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Experimental Setup Hardware setup: Pentium II 233 Mhz and Pentium Pro 300 Mhz Running either Linux or NT Benchmarking utilities: netperf (for max throughput) and netbench (for avg throughput) Netperf: Consists of 2 process: netserver and netperf Netperf connects to remote system running an instance of netserver and uses control connection to send parameters TCP connection using BSD sockets Separate connection for measurement Contd..
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Experimental Setup Netbench: Measures how well a file server handles I/O requests Each client tallies how many data moves to and from server
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Results Maximum throughput results: Message packet size varied from 2048 bytes to 4 Mbytes. After 16KByte packet size is reached, there is slight drop in performance and then again increase to give peak throughput of 190Mbps Performance peak in Linux system; NT system peak throughput around 90Mbps To investigate, NT experiment performed on different machine; peak throughput of 180 Mbps attained SUN’s Solaris attained peak performance of 488 Mbps Raw device testing attained performance of 700-800 Mbps at hardware level Average throughput results: Maximum server throughput of 157 Mbps with 3 clients
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High Quality Streaming Videos Criteria for experiment to measure concurrent access for on-demand video: Buffering Scheme: Used 2 buffer scheme at server: one to retrieve video frames from server system and other to transmit it to client Client also uses 2 buffer scheme: one for the network and other to display the frame Performance metrics for the measurement: Need to determine maximum number of concurrent accesses that can be supported by the network Need to calculate jitters (number of miss deadline retrievals)
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Results: On-Demand Video Streaming Range specifications of MPEG-2 between 4 and 32 Mbps were emulated Number of active processes were increased until system could no longer provide acceptable QoS (jitter less than 1%) Due to bus contention, 128 Mbps achieved for 32 streams of 4 Mbps videos Buffer size is another performance bottleneck in addition to network throughput
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Questions? You may send me a mail on my UF mail in case of any issues you need to communicate with me UF mail: varunpius@ufl.eduvarunpius@ufl.edu
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