Avaya 580 - Manual (Page 284)

9-6 User Guide for the Avaya P580 and P882 Multiservice Switches, v6.1
Chapter 9
Examples of Configuring VLANs and Hash Table
Size
Example 1 All VLANs have the same Hash Table Size
Configure the Avaya Multiservice switch for 45 VLANs. This requires the
default Hash Table size be reduced according to the hash table guidelines.
45 VLANs times 1024 = 46,080 or ~ 46K
This exceeds the 20K guideline for the amount of AFT memory used for
Hash Tables. Even if the Hash Table size is reduced by half, it still exceed
the guideline. In order to comply with the guideline, the Initial Hash Table
Size for each VLAN should be 256 or less. 45 VLANs times 256 = 11,520
or ~ 12K This leaves 48K for AFT entries (60K - 12K = 48K).
Example 2 VLANs have the different Hash Table Sizes
Configuring the Avaya Multiservice switch for 6 “large” VLANs (4000
users on each), 30 “medium” VLANs (1000 users on each), and 50 “small”
VLANs (200 users on each). Using the “Hash Table Guidelines”, each
“large” VLAN should have a hash table size around (1/4)*4000=1000, each
“medium” VLAN around (1/ 4)*1000=250, and each “small” VLAN should
have a hash table size around (1/4)*200=50. We also want to make sure that
the total amount of memory used for the Hash Tables is less then 20k, which
it will be (~17K).
6 VLANs times 1024 = 6,144
30 VLANs times 256 = 7,680
50 VLANs times 64 = 3,200
Total AFT Memory used or Hash Tables = 17,024 or ~ 17K
This meets the guideline.