Ip Ecmp-Group - Dell C9000 Series Reference Manual

Networking command-line reference guide

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The following is a list of the Dell Networking OS version history for this command.

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

The system 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.

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.

C9000 Series

ip ecmp-group {maximum-paths | {number} {path-fallback}

To negate a command, use the no ip ecmp-group maximum-paths {number}

Introduced on the C9010.

Introduced on the Z9500.

Introduced on the S4820T.

Introduced on the Z9000.

Introduced on the S4810.

Introduced on the E-Series.

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.

Equal Cost Multi-Path (ECMP)

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