Administrator Guide

NOTE: 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.
NOTE: If you remove the hash algorithm configuration, the hash seed does not return to the original factory default
setting.
To configure the hash algorithm seed, use the following command.
• Specify the hash algorithm seed.
CONFIGURATION mode.
hash-algorithm seed value [stack—unit stack—unit-number] [port-set number]
The range is from 0 to 4095.
Link Bundle Monitoring
Link bundle monitoring allows the system to monitor the use of multiple links for an uneven distribution.
Monitoring linked ECMP bundles allows traffic distribution amounts in a link to be monitored for unfair distribution at any given time. A
global default threshold of 60% is Link bundle monitoring allows the system to monitor the use of multiple links for an uneven distribution. .
Links are monitored in 15-second intervals for three consecutive instances. Any deviation within that time causes a syslog to be sent and
an alarm event generate. When the deviation clears, another syslog is sent and a clear alarm event generates. For example, link bundle
monitoring percent threshold:
%STKUNIT0-M:CP %IFMGR-5-BUNDLE_UNEVEN_DISTRIBUTION: Found uneven
distribution in LAG bundle 11.
Link bundle utilization is calculated as the total bandwidth of all links divided by the total bytes-per-second of all links. Within each ECMP
group, you can specify interfaces. If you enable monitoring for the ECMP group, utilization calculation performs when the utilization of the
link-bundle (not a link within a bundle) exceeds 60%.
Enable link bundle monitoring using the ecmp-group command.
NOTE:
An ecmp-group index is generated automatically for each unique ecmp-group when you configure multipath
routes to the same network. The system can generate a maximum of 512 unique ecmp-groups. The ecmp-group indexes
are generated in even numbers (0, 2, 4, 6... 1022) and are for information only.
For link bundle monitoring with ECMP, to enable the link bundle monitoring feature, use the ecmp-group command. In the following
example, the ecmp-group with id 2, enabled for link bundle monitoring is user configured. This is different from the ecmp-group index 2
that is created by configuring routes and is automatically generated.
These two ecmp-groups are not related in any way.
Example of Viewing Link Bundle Monitoring
DellEMC# show link-bundle-distribution ecmp-group 1
Link-bundle trigger threshold - 60
ECMP bundle - 1 Utilization[In Percent] - 44 Alarm State - Active
Interface Line Protocol Utilization[In Percent]
Gi 1/1 Up 36
Gi 1/1 Up 52
Managing ECMP Group Paths
To avoid path degeneration, configure the maximum number of paths for an ECMP route that the L3 CAM can hold. When you do not
configure the maximum number of routes, the CAM can hold a maximum ECMP per route.
To configure the maximum number of paths, use the following command.
NOTE:
For the new settings to take effect, save the new ECMP settings to the startup-config (write-mem) then reload
the system.
• Configure the maximum number of paths per ECMP group.
CONFIGURATION mode.
ip ecmp-group maximum-paths {2-64}
• Enable ECMP group path management.
CONFIGURATION mode.
Equal Cost Multi-Path (ECMP)
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