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9-8 User Guide for the Avaya P580 and P882 Multiservice Switches, v6.0
Chapter 9
Auto-Sizing is a feature that allows the Avaya Multiservice Switch to
automatically correct for an undersized hash table, which can result in poor
AFT memory utilization. Auto-Sizing consists of three parameters: Auto-
Increment, Trigger (Multiplier), and Threshold (Util%) in the Address
Forwarding Table Configuration
Figure 9-2. Address Forwarding Table Configuration
Auto-Increment
Auto-Increment is the Enable/Disable setting for the Auto-Sizing feature. If
Auto-Increment is enabled, the switch will automatically increase the hash
table size provided two conditions are met.See
Figure 9-1 for enabling or
disabling Auto-Increment HT size.
Trigger (Multiplier)
The first condition is the Trigger (Multiplier), which sets a minimum
threshold for the number of learned entries a VLAN must have before the
switch will consider increasing the Hash Table size. This prevents the
Avaya Multiservice Switch from resizing Hash Tables for VLANs who
have only a few AFT entries. This threshold is 12 times the Hash Table size.
For Example: If a VLAN is created with an Initial Hash Table Size of 64,
the trigger would be 12 times 64 = 768 learned entries. If there are more
than 768 learned entries, the second condition is evaluated.
Threshold (Util%)
The second condition is met if Bucket Utilization drops below the
Threshold (Util%), which by default is 40%. The switch will compensate
for the poor utilization by doubling the Hash Table. 40% is recommended
for most applications.