|
|
||||||||
|
|
|
||||||||
|
|
A
LAN switch is setup and looks similar to a shared Ethernet hub. The difference
is each port on the switch is considered a segment
and has dedicated bandwidth (10Mbps or 100 Mbps). Data is not forwarded
out of a segment unless addressed to a device on another segment. Then
that data is sent through the switch and routed to the segment, or port,
to its destination. None of the other segments have to "hear" the
traffic or interrupt their transmissions. Conversely a device on a shared
hub "hears" all sent data from every other device connected.
See the illustrated explanation of a shared hub. When a LAN switch first starts up and as the devices that are connected to it request services from other devices, the switch builds a table that associates the MAC address of each local device with the port number through which that device is reachable. Let us say station A is on one port, the printer is on another, station B is on a third port and the server is on the fourth. On a switch, station A can send a print job at the same time station B accesses the server. See the illustrated explanation of a switch. Whenever a device connected to the LAN switch sends a packet to an address that is not in the LAN switch's table or whenever the device sends a broadcast or multicast packet, the switch sends the packet out all ports but the originating port. This is referred to as flooding. Therefore, multicasts and broadcasts will slow even a "switched" network.
|
|
|||||||
