Setup Guide

Version Description
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.
ip ecmp-group
Enable and specify the maximum number of ecmp that the L3 CAM hold for a route, By default, when maximum paths are not
configured, the CAM can hold a maximum of 16 ecmp per route.
Syntax
ip ecmp-group {maximum-paths | {number} {path-fallback}
To negate a command, use the no ip ecmp-group maximum-paths {number} command.
Parameters
maximum-paths Specify the maximum number of ECMP for a route. The range is 2 to 64.
path-fallback Use the keywords path-fallback to enable this feature. If you enable the
feature, re-enter this keyword to disable the feature.
Defaults 16
Command Modes CONFIGURATION
Equal Cost Multi-Path (ECMP) 577