3Com CoreBuilder 3500, Implementation Manual

Page: 138 / 592

138 C
HAPTER
7: B
RIDGE
-W
IDE AND
B
RIDGE
P
ORT
P
ARAMETERS
MAC Address Table
The system includes several options for managing MAC addresses on
bridge ports. The system recognizes two different kinds of addresses:
■
Static MAC addresses — Addresses that you manually add to the
bridge address table using menu options. These addresses never age;
you must add and remove them manually.
■
Dynamic MAC addresses — Addresses that the bridge learns by
receiving and processing packets and ages. In the bridge address
table, each dynamic address is associated with a specific port and is
assigned an age so that it can be cleared from the table if the station is
inactive.
Your system can store up to 32 K addresses.
Aging Time The bridge aging time is the maximum period (in seconds) that
dynamically learned forwarding information (addresses) is held in the
bridge address table before it is aged out.
Use this parameter to configure the system to age addresses in a timely
manner, without increasing packet flooding beyond acceptable levels.
Address Threshold The address threshold is the value at which the system reports the total
number of addresses that are known. Specifically, when this threshold is
reached, the system generates the SNMP trap
addressThresholdEvent .
The range of values that you can enter for this parameter is between
1 and 1 plus the maximum address table size (32 K). Setting the address
threshold to one greater than the address table size prevents the system
from generating events because the limit can never be reached.
Important
Considerations
■
All dynamic addresses are flushed from the bridge address table
whenever you cycle power to the system or reboot the system. All
dynamic addresses are also flushed when STP reconfigures the
topology. Both dynamic and static addresses are flushed when you
reset nonvolatile data.
■
If you have multiple ports associated with a trunk, the addresses that
are defined for the anchor port apply to all ports in the trunk.
■
You can remove individual MAC addresses from selected ports.
Typically, this action is only applied to static addresses because the
system can quickly relearn dynamic addresses that you remove.