Configuring And Displaying The Hre-X Hash Table; Index - Alcatel Omni Switch/Router User Manual

Configuring and Displaying the HRE-X Hash Table
The s use a hardware implemented hash table to route packets for transmission. The
HRE-X
switch employs a default hash function that works well in a broad range of data environ-
ments. In rare cases, you may want to change the hash table configuration to optimize it for
your particular data flow. This should be done with care because the data population will
change over time. A hash function that works well for one set of data may not work as well
for another. Also, note that optimizing the hash function will cause all of the current entries in
the to be cleared and then relearned; therefore, this should be done with extreme
HRE-X
caution.
Two commands are used to optimize the hash function. They are the
HRE-X
commands. The
table. To view the
HRE-X
at the system prompt. A screen similar to the following is displayed.
The fields displayed by the
. The number of entries in the hash table.
. The total number of units available.
. The number of units that are not yet used.
. The number of entries that have hashed to the same index in the hash table.
. The number of modifications required to route a packet.
. The length of the longest (
the collision lists.
The command causes the switch to compute an optimized hash function based
on the data currently in the HRE-X. This function is saved in the configuration file so it will be
present after a reboot.
To use the
at the system prompt. The screen does not display a confirmation message after this
command. You can verify optimization by observing the changes in the HRE-X Utilization.
After using
shown in the HRE-X Utilization table shown above. If they are not, you should consider
returning to the default hash function by using the
To use the
at the system prompt. The screen does not display a confirmation message after this
command. The
command displays the current utilization of the hash
Utilization table, enter
command are described below:
) collision list and the average length (
command, enter
, the maximum and average collision lengths should be reduced as
command, enter
command will return the hash function back to the default value.
Configuring the HRE-X Router Port
and the
command.
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