How a Bridge Ages Addresses5-3
How a Bridge A source address remains in the address table as long as the station to which
Ages Addressesit relates regularly transmits through the bridge. If the station does not
regularly transmit, the source address is Oaged out� of the bridgeOs table.
Address aging is primarily implemented to ensure that if a station moves to
a different segment on the network, its address will be forgotten at the old
location and packets will no longer be forwarded to that location. Address
aging is also necessary because a bridge can learn only a Ţnite number of
addresses. The Switch 2200 system, when conŢgured as an IEEE 802.1d
bridge, can learn up to 8K addresses in its address table.
Address aging, although typically an efŢcient means of maintaining a
current address table, can create problems when regularly used stations on
the network do not transmit periodically. For instance, printers only transmit
when they are powered on, yet printing is a function performed frequently
on a network. In this case, the printerOs address is aged out of the address
table and the bridge no longer has the information it needs to send packets
directly to that station.
To handle this situation, the Switch 2200 system allows you to statically
conŢgure the addresses of these stations. Because a statically conŢgured
address is not aged out of memory, it must be manually �ushed when the
station is removed from the network. Static conŢguration of Ethernet
addresses and �ushing static Ethernet addresses are described in the
SuperStacka II Switch 2200 Administration Console User Guide. |
ACEC
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