Cabletron Systems SEHI-22/24, User Manual

Page: 54 / 90

Source Addressing
5-4 Setting the Hash Type
Setting the Ageing Time
The source address list Ageing Time determines the minimum amount of time an
inactive source address will remain in the Source Address Table before it is
purged. The source address timer runs continuously beginning at the time the
device is turned on; source addresses that are added to the SAT during one timer
cycle will remain in the table for the rest of the current cycle and at least through
the next complete cycle. If no packets have been received from that address
during one complete cycle, the address will be purged.
The Ageing Time is user-configurable, and can be set using the Ageing Time text
box in the Source Address list window.
To change the Ageing Time:
1. In the Source Address List window ( Figure 5-2 , page 5-3 ), highlight the
displayed ageing time.
2. Enter your desired ageing time in minutes; allowable range is 0 to 4320 (three
days).
3. Click mouse button 1 on to save your change.
The new Ageing Time takes effect immediately.
Setting the Hash Type
You can increase the efficiency with which your SEHI handles the Source Address
Table by selecting the appropriate hashing algorithm. If you are operating in a
DECnet environment, or one which incorporates some DECnet elements, select
the DEC hashing algorithm; if your network contains no DECnet elements (or at
least none operating on the same network segment as your SEHI), select the non-
DEC hashing algorithm. Making the wrong selection won’t do any damage, but
making the correct selection will optimize performance.
To set the Hash Type for a repeater interface, or channel:
1. In the Repeater Source Address window, click mouse button 1 on the repeater
interface for which you would like to set the hash type.
NOTE
The snapshots of the Source Address List that you can obtain via this feature do not reflect
the current port security status of the SAT — that is, when Source Address Locking is
enabled, you can still observe addresses being aged out of the table (for all ports) and new
addresses being added (for trunk ports) as you refresh the Source Address List displayed
in this window. However, the SEHI remembers the addresses that were in the table when
locking was enabled, and will continue to protect station ports (and, in later versions of
EMME/EMM-E6 firmware, RIC MIM trunk ports) from access by unauthorized sources.
For more information, see
Locking Source Addresses , page 5-5 .