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| 作者：不明 来源：www.pccode.net 整理 发布时间：2007-1-24 15:24:00 发布人：wongrs | |
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eater- regenerates signals for tx, pass broadcasts, no unlike phys media. (Physical). Hubs- one tx, all other rx, simplex, no addressing(Physical).Multiplexer- for multiplexing links.(Physical) Repeater reduces dist for 100BaseFx due to delays, but extends 100BaseTx dist. Class1:Translational rptr supports both 100baseX and 100baset4 signalling. Delay=140 bit times, Class 2:Transparent rptr only supports either 100baseX or 100baseT4, not both at same time.delay=92 bit times. FastHub300: Rptr compatible with 802.3u for fast Enet. LAN Switching : Uses dest MAC add to forwd pkts. same as multi port Bridge. Multi simultaneous convs, high speed data exges, low latency & high frame fowd rates, full duplex, media rate adaption (10/100). Port Switching: port assigned to a phys net by software. Frame Switching: increases b/w on the net. Allows multi trans in parallel. used in Cisco Cata switch. Cell Switching: ATM. Uses small fixed length cells that are switched on the net. Used in Cisco light stream switches. Router Switching : Store & Forward: copies entire frame in to buffers and checks CRC. Forwards 64-1518 Bytes only. latency high depends on Frame Length. used in cat 05000/5505 series. Cut-through (Real Time): copies only dest add (6B) in to buffers. some switches automly uses both modes, Low latency, 10/100mb full duplex Fragment Free: modified cut thro. Waits for collision window (first 64 B). Better error checking, no latency. Spanning-Tree Protocol (STP) IEEE 802.1d- to prevent routing loops. STA (Spanning-Tree Algorithm) is impled by STP to calculate a loop-free net topology. In Cat 5000 based nets Bridge proto data units (BPDU) are sent & recd by all switch in regular intervals & processed to determine spanning-tree topology. Virtual LAN’s-have diff ports of a switch be parts of diff sub nets. can be by location, function, grp & dept. Simplify moves, adds, changes. less admn costs, better control of broadcasts, tighten net security, distribute load, Relocate server into secured locations. Frame tagging: A user defined ID for each frame, places a unique user defined ID in the header of each frame used within switch fabric itself. Used in Cat 3000 & 5000 series. Developed for multi VLAN, Inter switch Commn, needs processor & admn load. IP Address Classes: (2)192-2-4194302-16382-62 Class A Net.Node.Node.Node 0 1-127 12
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