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Annotated edit history of EthernetSwitch version 4, including all changes. View license author blame.
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4 CraigMckenna 1 An ethernet switch has a number of ethernet ports, usually [10BaseT], [100BaseT], and [1000BaseT]. A switch receives ethernet frames on every port and based on the destination MAC address, forwards them out another port. Switches of these type tend to be store-and-forward devices, receiving the entire frame and doing a lookup against the MAC table for destination ports.
1 JamesSpooner 2
2 PerryLorier 3 The MAC table is updated on reception of packets from a source [MAC] address, for each MAC address an entry in that ports MAC forwarding table is added.
1 JamesSpooner 4
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6 The quality of a switch usually depends on a number of factors.
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2 PerryLorier 8 !!Manageability is a key factor.
1 JamesSpooner 9
2 PerryLorier 10 Managed switches allow the administrator to use [SNMP]/Telnet/[WWW]/etc. to configure and monitor a particular switch. This enables fine tuning of the switches performance and bandwidth graphs to be generated for each port, etc.
1 JamesSpooner 11
2 PerryLorier 12 !!Switch Fabric Bandwidth.
1 JamesSpooner 13
14 The amount of bandwidth on the switch fabric dictates how much data can be switched in any one second. If data cannot be switched, it will be stored in a (small) buffer on the incoming port. If this buffer fulls up the packet is dropped.
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2 PerryLorier 16 !!Per-Port Buffer Size
1 JamesSpooner 17
2 PerryLorier 18 If the switch is blocking packet due to high demand, the [FIFO] buffer on the incoming port may be used. The larger this buffer is - the less likely the packet is to be dropped.
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2 PerryLorier 20 !!Maximum MAC addresses
1 JamesSpooner 21
2 PerryLorier 22 This is not usually a problem, a ethernet [MAC] is 6 bytes, most switches claim 4k [MAC] addresses per port, this is only 24kB of [RAM] per port - the buffer size (up to multiple MB) is much more important.
1 JamesSpooner 23
24 Some high-end ventors implement SpanningTree on their managed switches to improve the fault tolerance on the network.
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2 PerryLorier 26 To improve performance, [Layer3Switching] is employed to reduce the size of the ethernet broadcast domain.
3 JohnMcPherson 27
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29 Part of CategoryNetworking