Users Guide

Term heading Description heading
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.
hash-algorithm seed
Select the seed value for the ECMP, LAG, and NH hashing algorithm.
S4820T
Syntax
hash-algorithm seed value [stack-unitslot/port] [port-set number]
Parameters
seed value Enter the keyword seed then the seed value. The range is from 0 to
2,147,483,646.
stack–unit slot/
port
Enter the keyword stack-unit then the slot/port number.
port-set number Enter the keyword port-set then the port-pipe number. The value is 0.
Defaults None
Command Modes CONFIGURATION
Command History
This guide is platform-specific. For command information about other platforms, see the relevant Dell
Networking OS Command Line Reference 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.
8.3.19.0 Introduced on the S4820T.
8.3.11.1 Introduced on the Z9000.
8.3.7.0 Introduced on the S4810.
8.3.1.0 Introduced on the E-Series.
Usage Information Deterministic ECMP sorts ECMPs in order even though RTM provides them in a random order. However,
the hash algorithm uses as a seed the lower 12 bits of the chassis MAC, which yields a different hash
result for every chassis. This behavior means that for a given flow, even though the prefixes are sorted,
two unrelated chassis select different hops.
Equal Cost Multi-Path (ECMP) 590