Reference Guide

Interfaces | 383
Figure 20-15. Command example: hash seed
On S-Series, the hash-algorithm command is specific to ECMP groups. The default ECMP hash algorithm
is crc32MSB. This takes the lower 32 bits of the hash key to compute the egress port. Other options for
ECMP hash-algorithms are:
• crc16 -- uses 16 bit CRC16-bisync polynomial
• crc16cc -- uses 16 bit CRC16 using CRC16-CCITT polynomial
• crc32LSB -- uses LSB 16 bits of computed CRC32
• crc32MSB -- uses MSB 16 bits of computed CRC32(default)
• crc-upper -- uses Upper 32 bits of key for hash computation
• dest-ip -- uses Destination IP for ECMP hashing
• lsb -- uses Always return the LSB of the key as the hash
• xor1 -- uses Upper 8 bits of CRC16-BISYNC and lower 8 bits of xor1
• xor2 -- Upper 8 bits of CRC16-BISYNC and lower 8 bits of xor2
• xor4 -- Upper 8 bits of CRC16-BISYNC and lower 8 bits of xor4
• xor8 -- Upper 8 bits of CRC16-BISYNC and lower 8 bits of xor8
• xor16 -- uses 16 bit XOR
To change to another method, use the following command in the CONFIGURATION mode:
Command Syntax Command Mode Purpose
hash-algorithm
[ecmp{crc16|crc16cc|crc32LSB|crc3
2MSB|crc-upper|dest-ip|lsb|xor1|xor
2|xor4|xor8|xor16}]
CONFIGURATION Change to another algorithm.
FTOS(conf)#hash-algorithm seed 500
FTOS(conf)#do show hash-algorithm
Hash-Algorithm
Stack-unit 0 Port-Set 0
Seed 500
Hg-Seed 1197460041
EcmpAlgo- crc32MSB LagAlgo- crc32LSB HgAlgo- crc16
Stack-unit 1 Port-Set 0
Seed 500
Hg-Seed 1197460041
EcmpAlgo- crc32MSB LagAlgo- crc32LSB HgAlgo- crc16