Reference Guide

Usage
Information
To ensure that CRC is not used for LAG, set the default hash-algorithm method. For example,hash-
algorithm ecmp xor lag checksum nh-ecmp checksum.
The hash value calculated with the hash-algorithm command is unique to the entire chassis. The hash
algorithm command with the line card option changes the hash for a particular line card by applying the
mask specified in the IPSA and IPDA fields.
The line-card option is applicable with the lag-hash-align microcode only. Any other microcode returns an
error message as follows:
● Dell(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 slot-id 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, the system maintains bi-directionality with masks set to
XX 00 for line card 1 and 00 XX for line card 2 (ip-sa-mask and ip-da-mask). The mask value
must be the same for both line cards when using multiple line cards as ingress (where XX is any value
from 00 to FF for both line cards). For example, assume that traffic is flowing between line card 1 and
line card 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 different 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 traffic, 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 traffic across the members.
hash-algorithm ecmp
Change the hash algorithm used to distribute traffic flows across an ECMP (equal-cost multipath routing) group.
Z9500
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, refer to the relevant Dell
Networking OS Command Line Reference Guide.
The following is a list of the Dell Networking OS version history for this command.
554 Equal Cost Multi-Path (ECMP)