Users Guide

The hash value calculated with the hash-algorithm command is unique to the entire unit. The hash algorithm
command with the stack-unit option changes the hash for a particular stack-unit by applying the mask specied in
the IPSA and IPDA elds.
The stack-unit option is applicable with the lag-hash-align microcode only. Any other microcode returns an error
message as follows:
• DellEMC(conf)#hash-algorithm linecard 5 ip-sa-mask ff ip-da-mask ff
• % Error: This command is not supported in the current microcode configuration
In addition, the linecard number ip-sa-mask value ip-da-mask value option has the following
behavior to maintain bi-directionality:
• When hashing is done on both IPSA and IPDA, the ip-sa-mask and ip-da-mask values must be equal.
(Single Linecard).
• When hashing is done only on IPSA or IPDA, Dell EMC Networking OS maintains bi-directionality with masks
set to XX 00 for stack-unit 1 and 00 XX for stack-unit 2 (ip-sa-mask and ip-da-mask). The mask value
must be the same for both stack-units when using multiple stack-units as ingress (where XX is any value from
00 to FF for both stack-units). For example, assume that trac is owing between linecard 1 and linecard 2:
• hash-algorithm linecard 1 ip-sa-mask aa ip-da-mask 00
• hash-algorithm linecard 2 ip-sa-mask 00 ip-da-mask aa
The dierent hash algorithms are based on the number of Port Channel members and packet values. The default
hash algorithm (number 0) yields the most balanced results in various test scenarios, but if the default algorithm
does not provide a satisfactory distribution of trac, use the hash-algorithm command to designate another
algorithm.
When a Port Channel member leaves or is added to the Port Channel, the hash algorithm is recalculated to balance
trac across the members.
hash-algorithm ecmp
Change the hash algorithm used to distribute trac ows 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
676 Equal Cost Multi-Path (ECMP)