Command Line Reference Guide

hash-algorithm ecmp
Change the hash algorithm used to distribute traffic flows across an ECMP (equal-cost multipath routing) group.
S5000
Syntax
hash-algorithm ecmp {crc-upper} | {crc} | {dest-ip} | {lsb} |
{xor}
To return to the default hash algorithm, use the no hash-algorithm ecmp command.
Parameters
crc Uses specified polynomicals or bits of computed cyclic redundancy
checks (CRC) for the hash computation.
crc-upper Uses the upper 32 bits of the key for the hash computation.
dest-ip Uses the destination IP for ECMP hashing.
lsb Returns the LSB of the key as the hash.
xor Uses the lower 8 bits of the key for the hash computation.
Defaults
• crc-lower
• dest-ip enabled
Command Modes CONFIGURATION
Command History
Version 9.0(1.3) Introduced on the S5000.
Usage
Information
The hash value calculated with the hash-algorithm command is unique to the entire chassis.
The default ECMP hash configuration is crc-lower. This takes the lower 32 bits of the hash key
to compute the egress port and is the “fall-back” configuration if you have not configured
anything else.
The different hash algorithms are based on the number of ECMP group members and packet
values. The default hash algorithm yields the most balanced results in various test scenarios,
but if the default algorithm does not provide satisfactory distribution of traffic, use this
command to designate another algorithm.
When a member leaves or is added to the ECMP group, the hash algorithm is recalculated to
balance traffic across the members.
Related
Commands
load balance
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