HP 10:10 LAN Bridge MB, Installation And Reference Manual

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Address Table
The address table is in the bridge’s battery-backed RAM. The table can hold up to 512 entries.
Each entry contains the station address (also known as a MAC address, or Ethernet address) of
a node on one of the attached networks, the port ID associated with the station address, and an
indication of the type of address it is: dynamic, permanent, or static. Address table changes can
be made through the bridge console interface, or from an HP network management station.
Dynamic Addresses. Dynamic addresses are the node addresses that the bridge learns after
it is connected to the network. These addresses are used to prevent the bridge from forwarding
packets to the opposite LAN when the source and destination nodes are on the same LAN.
To assure that the address table accurately reflects the current position of the bridge in the
network, the dynamic addresses are “aged out” of the table. If the bridge does not see a packet
with a given source address for 300 seconds, that address is deleted from the table.
Permanent Addresses. These addresses come pre-configured into the address table and
cannot be deleted or changed. They include the bridge’s own station address, specific
broadcast and multicast addresses, spanning tree broadcast addresses, and reserved 802.1
addresses. Packets with the broadcast addresses are forwarded. Packets with the 802.1
addresses are filtered. Packets with the other permanent addresses are used by the bridge for
various purposes. The bridge operating state has no effect on the handling of packets with
these addresses.
There are 20 permanent addresses if STP is enabled for your bridge (bridge operating state is
Learning/STP or Secure/STP). If not, there are 19 permanent addresses.
How the Bridge Works 6-3