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lect09-ethernet-infiniband - switched physical medium to...

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CMSC 714 Lecture 9 Ethernet and Infiniband Alan Sussman 2 CMSC 714 - Alan Sussman Notes ! OpenMP assignment due Wednesday don’t compile for profiling (with –pg) and for OpenMP at same time when you time runs with multiple threads, make sure enough cores are available – wall clock timings with threads sharing cores will not give useful results other questions? ! Sample topics for group project posted 3 Ethernet ! One of the first, and definitely the most successful, local area network (LAN) protocol and implementation ! Notice that also targeted at multiprocessing, not just distributed computing ! CSMA/CD wire protocol – carrier sense multiple access, with collision detection a shared physical medium, even with repeaters randomized exponential backoff after a collision error detection using checksums on medium, still need end- to-end error detection since whole packets can be lost ! Modern Ethernet protocols are different – for a
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Unformatted text preview: switched physical medium to scale better – original at 3Mb/s (shared), 1Gb/sec (switched) common now, with 10Gb/sec and soon 100Gb/sec in HPC environments CMSC 714 - Alan Sussman 4 Infiniband ! Designed to support I/O and network connectivity, from a single PCB to a cluster network to a LAN – over copper (twisted pairs) and fiber ! Targeted at cluster networks, SANs, and even embedded systems – scalable, and provides RAS – “bandwidth out of the box” – idea is to extend the on-processor I/O bus to off-chip network ! Switched ooint-to-point I/O fabric – endpoints (host machines, I/O devices, …) connect to switches, which route connections to other endpoints – link speed from 2.5Gb/sec (1X) to 30GB/sec (12X) by adding more wires – parallel transfers ! Protocols described in terms of standard network layers – physical, link, network, transport CMSC 714 - Alan Sussman...
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