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Berkeley COMPSCI 61C - Lecture Notes

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PowerPoint PresentationI/O ReviewPeer InstructionPeer Instruction AnswerBuses in a PC: connect a few devices (2002)Shared vs. Switched Based NetworksWhy Networks?How Big is the Network (1999)?Growth RateWhat makes networks work?Typical Types of NetworksThe Sprint U.S. Topology (2001)ABCs of Networks: 2 ComputersA Simple Example: 2 ComputersQuestions About Simple ExampleABCs: many computersSlide 17Slide 18Observations About Simple ExampleSoftware Protocol to Send and ReceiveProtocol for Networks of Networks?Protocol Family ConceptSlide 23Protocol for Network of NetworksTCP/IP packet, Ethernet packet, protocolsOverhead vs. BandwidthSlide 27Slide 28And in conclusion…CS61C L39 I/O : Networks (1)Garcia, Fall 2004 © UCBLecturer PSOE Dan Garciawww.cs.berkeley.edu/~ddgarciainst.eecs.berkeley.edu/~cs61c CS61C : Machine StructuresLecture 39 I/O : Networks2004-12-01USA Today and Avantegardereport that it took less than 4 min for an unprotected PC running XP SP1 to be compromised. The Mac and Linux box were attacked but didn’t fall. Clean to Zombie Bot in 4min www.usatoday.com/money/industries/technology/2004-11-29-honeypot_x.htmCS61C L39 I/O : Networks (2)Garcia, Fall 2004 © UCBI/O Review•I/O gives computers their 5 senses•I/O speed range is 12.5-million to one•Processor speed means must synchronize with I/O devices before use•Polling works, but expensive•processor repeatedly queries devices•Interrupts works, more complex•devices causes an exception, causing OS to run and deal with the device•I/O control leads to Operating SystemsCS61C L39 I/O : Networks (3)Garcia, Fall 2004 © UCBPeer InstructionA. A faster CPU will result in faster I/O.B. Hardware designers handle mouse input with interrupts since it is better than polling in almost all cases.C. Low-level I/O is actually quite simple, as it’s really only reading and writing bytes. ABC1: FFF2: FFT3: FTF4: FTT5: TFF6: TFT7: TTF8: TTTCS61C L39 I/O : Networks (4)Garcia, Fall 2004 © UCBPeer Instruction AnswerA. A faster CPU will result in faster I/O.B. Hardware designers handle mouse input with interrupts since it is better than polling in almost all cases.C. Low-level I/O is actually quite simple, as it’s really only reading and writing bytes. ABC1: FFF2: FFT3: FTF4: FTT5: TFF6: TFT7: TTF8: TTTF A L S ET R U EA. Less sync data idle timeB. Because mouse has low I/O rate polling often usedC. Concurrency, device requirements vary!F A L S ECS61C L39 I/O : Networks (5)Garcia, Fall 2004 © UCBBuses in a PC: connect a few devices (2002)CPUMemory busMemorySCSI:External I/O bus(1 to 15 disks)SCSI InterfaceEthernet InterfaceEthernet Local Area Network•Data rates (P4)•Memory: 400 MHz, 8 bytes 3.2 GB/s (peak)•PCI: 100 MHz, 8 bytes wide  0.8 GB/s (peak)•SCSI: “Ultra4” (160 MHz), “Wide” (2 bytes)  0.3 GB/s (peak)GigabitEthernet: 0.125 GB/s (peak)PCI InterfacePCI: Internal(Backplane) I/O busBus - shared medium of communication that can connect to many devices. Hierarchy!!CS61C L39 I/O : Networks (6)Garcia, Fall 2004 © UCBShared vs. Switched Based Networks•Shared Media vs. Switched: in switched, pairs (“point-to-point” connections) communicate at same time; shared 1 at a time•Aggregate bandwidth (BW) in switched network ismany times shared:•point-to-point faster since no arbitration, simpler interfaceNodeNode NodeSharedCrossbarSwitchNodeNodeNodeNodeCS61C L39 I/O : Networks (7)Garcia, Fall 2004 © UCBWhy Networks?•Originally sharing I/O devices between computers (e.g., printers)•Then Communicating between computers (e.g, file transfer protocol)•Then Communicating between people (e.g., email)•Then Communicating between networks of computers  File sharing, WWW, …CS61C L39 I/O : Networks (8)Garcia, Fall 2004 © UCBHow Big is the Network (1999)?Computers in 273 Sodain inst.cs.berkeley.eduin eecs&cs .berkeley.eduin berkeley.eduin .edu in US(.com .net .edu .mil .us .org)in the worldSource: Internet Software Consortium~30~400~4,000~50,000~5,000,000~46,000,000~56,000,000CS61C L39 I/O : Networks (9)Garcia, Fall 2004 © UCBGrowth RateEthernet Bandwidth1983 3 mb/s1990 10 mb/s1997 100 mb/s1999 1000 mb/s2004 10 Gig E(to come!)010,000,00020,000,00030,000,00040,000,00050,000,00060,000,00070,000,00080,000,00090,000,000100,000,000Jan-93 Apr-95 Jun-97 Aug-99 Internet Hosts "Source: Internet Software Consortium (http://www.isc.org/)".CS61C L39 I/O : Networks (10)Garcia, Fall 2004 © UCBWhat makes networks work?•links connecting switches to each other and to computers or devicesComputernetworkinterfaceswitchswitchswitch•ability to name the components and to route packets of information - messages - from a source to a destination•Layering, protocols, and encapsulation as means of abstraction (61C big idea)CS61C L39 I/O : Networks (11)Garcia, Fall 2004 © UCBTypical Types of Networks•Local Area Network (Ethernet)•Inside a building: Up to 1 km•(peak) Data Rate: 10 Mbits/sec, 100 Mbits /sec,1000 Mbits/sec (1.25, 12.5, 125 MBytes/s)•Run, installed by network administrators•Wide Area Network•Across a continent (10km to 10000 km)•(peak) Data Rate: 1.5 Mb/s to 10000 Mb/s•Run, installed by telecommunications companies (Sprint, UUNet[MCI], AT&T)• Wireless Networks (LAN), ...CS61C L39 I/O : Networks (12)Garcia, Fall 2004 © UCBThe Sprint U.S. Topology (2001)CS61C L39 I/O : Networks (13)Garcia, Fall 2004 © UCBABCs of Networks: 2 Computers•Starting Point: Send bits between 2 computers•Queue (First In First Out) on each end•Can send both ways (“Full Duplex”)•Information sent called a “message”•Note: Messages also called packetsnetworkinterfacedeviceOSapplnOSapplnCS61C L39 I/O : Networks (14)Garcia, Fall 2004 © UCBA Simple Example: 2 Computers•What is Message Format?•Similar idea to Instruction Format•Fixed size? Number bits?•Header(Trailer): information to deliver message•Payload: data in message•What can be in the data?•anything that you can represent as bits•values, chars, commands, addresses...8 bit32 x Length bitsDataLengthCS61C L39 I/O : Networks (15)Garcia, Fall 2004 © UCBQuestions About Simple Example•What if more than 2 computers want to communicate?•Need computer “address field” in packet to know which computer should receive it (destination), and to which computer it came from for reply (source) [just like envelopes!]8 bits32xn bits8 bits 8 bitsHeader PayloadCMD/ Address /DataNet ID Net


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Berkeley COMPSCI 61C - Lecture Notes

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