Reference Guide

Equal Cost Multi-Path | 519
Related
Commands
hash-algorithm ecmp
c s
Change the hash algorithm used to distribute traffic flows across an ECMP
(equal-cost multipath routing) group.
Syntax
hash-algorithm ecmp {crc-upper} | {dest-ip} | {lsb}
To return to the default hash algorithm, use the
no hash-algorithm ecmp command.
Parameters
Defaults
crc-lower, dest-ip enabled
Command Modes
CONFIGURATION
Command
History
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
the user hasn’t 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, then 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.
12 - 23
Compression Enabled
shift [0 - 11]
24 - 35
Compression Disabled
rotate [0 - 11]
36 - 47
Compression Disabled
shift [0 - 11]
load-balance (E-Series) Change the traffic balancing method.
crc-upper
Uses the upper 32 bits of the key for the hash computation
Default: crc-lower
dest-ip
Uses the destination IP for ECMP hashing
Default: enabled
lsb
Returns the LSB of the key as the hash
Default: crc-lower
Version 7.6.1.0 Introduced on S-Series
Version 7.5.1.0 Introduced on C-Series