Concept Guide

Supported Modes Full–Switch
Command History
Version Description
9.9(0.0) Introduced on the FN IOM.
9.2(0.0) Introduced on the MXL 10/40GbE Switch IO Module.
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 dierent hash result for every
chassis. This behavior means that for a given ow, even though the prexes are sorted, two unrelated chassis
select dierent hops.
The Dell Networking OS provides a CLI-based solution for modifying the hash seed to ensure that on each
congured system, the ECMP selection is same. When congured, the same seed is set for ECMP, LAG, and NH,
and is used for incoming trac 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 dierent 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 conguration is removed, the hash seed does not go to the original factory default
setting.
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 congured,
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 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
Supported Modes Full–Switch
Command History
Version Description
9.9(0.0) Introduced on the FN IOM.
9.2(0.0) Introduced on the MXL 10/40GbE Switch IO Module.
Usage Information You must save the new ECMP settings to the startup-cong (write-mem) then reload the system for the new
settings to take eect.
Related Commands show ip cam stack-unit — Display content-addressable memory (CAM) entries.
472 Equal Cost Multi-Path (ECMP)