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Dell PowerEdge FN I/O Module Command Line Reference Guide 9.10(0.0)

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hash-algorithm ecmp

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

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

Supported Modes

Full–Switch

Command History

Version	Description
9.9(0.0)	Introduced on the FN IOM.
9.2(0.0)	Introduced on the MXL 10/40GbE Switch IO Module.

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.