Administrator Guide

Version Description
9.8(0.0P5) Introduced on the S4048-ON.
9.8(0.0P2) Introduced on the S3048-ON.
9.7(0.0) Introduced on the S6000-ON.
9.2(1.0) Introduced on the Z9500.
9.0.2.0 Introduced on the S6000.
8.3.19.0 Introduced on the S4820T.
8.3.11.1 Introduced on the Z9000.
8.3.10.0 Introduced on the S4810.
8.1.1.0 Introduced on the E-Series.
7.8.1.0 Added the nh-ecmp option.
7.7.1.1 Added the nh-ecmp option.
Usage Information To ensure that CRC is not used for LAG, set the default hash-algorithm method on E-Series systems. 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 unit. The hash algorithm
command with the stack-unit option changes the hash for a particular stack-unit by applying the mask specified in
the IPSA and IPDA fields.
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 traffic is flowing 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 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.
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.
584 Equal Cost Multi-Path (ECMP)