Dell Command Line Reference Guide for the S4048–ON System 9.14.2.5

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hash-algorithm ecmp

Change the hash algorithm used to distribute traffic flows across an ECMP (equal-cost multipath routing) group.

Term heading
Description heading
Syntax
hash-algorithm ecmp {crc-upper} | {dest-ip} | {lsb}

To return to the default hash algorithm, use the no hash-algorithm ecmp command.

Parameters
crc-upper
Uses the upper 32 bits of the key for the hash computation. The default is crc-lower.
dest-ip
Uses the destination IP for ECMP hashing. The default is enabled.
lsb
Returns the LSB of the key as the hash. The default is crc-lower.
Defaults
  • crc-lower
  • dest-ip enabled
Command Modes
CONFIGURATION
Command History

This guide is platform-specific. For command information about other platforms, see the relevant Dell Networking OS Command Line Reference Guide.

Version
Description
9.8(0.0P5)
Introduced on the S4048-ON.
9.8(0.0P2)
Introduced on the S3048-ON.
8.3.19.0
Introduced on the S4820T.
8.3.11.1
Introduced on the Z9000.
8.3.7.0
Introduced on the S4810.
8.1.1.0
Introduced on the E-Series.
7.6.1.0
Introduced on the S-Series.
7.5.1.0
Introduced on the C-Series.
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 command 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.


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