Reference Guide

266 | Equal Cost Multi-Path (ECMP)
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Monitoring linked ECMP bundles allows traffic distribution amounts in a link to be monitored for unfair
distribution at any given time. A default threshold of 60% is defined as an acceptable amount of traffic on
a member link. 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 to be generated. When the deviation clears,
another syslog is sent and a clear alarm event is generated.
The 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, interfaces can be specified. If monitoring is
enabled for the ECMP group, the utilization calculation is performed when the utilization of the
link-bundle (not a link within a bundle) exceeds 60%.
Enable link bundle monitoring using the
ecmp-group command.
Managing ECMP Group Paths
Managing ECMP Group Paths is supported only on platforms: z
Configure the maximum number of paths for an ECMP route that the L3 CAM can hold to avoid path
degeneration. When the maximum number of routes is not configured, the CAM can hold a maximum
ECMP per route.
Message 1 Link bundle monitoring percent threshold
%STKUNIT0-M:CP %IFMGR-5-BUNDLE_UNEVEN_DISTRIBUTION: Found uneven distribution in LAG bundle 11.
Note: An ecmp-group index is generated automatically for each unique ecmp-group when the user
configures 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, the ecmp-group command is used to enable the link bundle monitoring
feature. 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.