HP J4868A, Install Manual

Page: 13 / 60

1-7
Introducing the HP Procurve Switch 2124
Switch Operation Overview
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Forwarding, Filtering, Flooding. When the switch receives a packet, it
determines the destination address, and looks for the address in the address
table. Based on the port location of that address, the switch then determines
whether to forward, filter-out, or flood the packet.
■ forward - if the destination address is on a different port than the one on
which the packet was received, the packet is forwarded to the destination
port and on to the destination device.
■ filter out - if the destination address is on the same port as the one on
which the packet was received, the packet is filtered out. The switch
thereby isolates local traffic so the rest of the network connected to the
switch does not use bandwidth dealing with unnecessary traffic.
■
flood - whenever a new destination address is found in a packet received
on a port, the destination address will not yet be in the switch’s address
table and the Switch 2124 cannot know whether to forward or filter out
the packet. In this case, it sends the packet to all the other switch ports.
This is referred to as “flooding”. When the destination device receives the
packet, it replies, and the switch learns the new address from the reply
packet. Then, all future packets destined for that address are forwarded
or filtered out appropriately.
Network Moves and Changes. When devices are moved in the network,
and become connected to a different switch port, the Switch 2124 automati-
cally recognizes the change and updates the address table with the new port
location of the device. Communication with the device is automatically main-
tained, without any address table manipulation being required.