Dell Command Line Reference Guide for the S4048–ON System 9.14.2.5

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hash-algorithm seed

Select the seed value for the ECMP, LAG, and NH hashing algorithm.

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[subport] 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.

Dell provides a CLI-based solution for modifying the hash seed to ensure that on each configured system, the ECMP selection is same. When configured, the same seed is set for ECMP, LAG, and NH, and is used for incoming traffic only.

NOTE: While the seed is stored separately on each port-pipe, the same seed is used across all CAMs.

You cannot separate LAG and ECMP but you can use different algorithms across the chassis with the same seed. If LAG member ports span multiple port-pipes and line cards, set the seed to the same value on each port-pipe to achieve deterministic behavior.

If the hash algorithm configuration is removed, the hash seed does not go to the original factory default setting.


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