Reference Guide

● A line-card (leaf) NPU supports 12 front-end I/O ports and 12 backplane HiGig ports. The 12 backplane links are members of
a single HiGig link bundle that connects the line-card NPU to each SFM (spine) NPU. Two HiGig links in the bundle are used
to connect to each SFM NPU.
You can enable the capability to detect uneven traffic distribution in the member links of a HiGig link bundle on a line-card or
SFM NPU. You can also enable a notification to be sent using alarms and SNMP traps. The algorithm used to determine uneven
distribution of traffic is predefined.
Monitoring HiGig link bundles allows you to view and analyze unequal traffic flow in backplane port channels and take corrective
action. Alarms are generated if the link-bundle traffic threshold is greater than the configured threshold and the unevenness is
greater than 10 percent between links for three successive rate-intervals. Alarms are removed when the link-bundle threshold is
lower than the configured threshold and the unevenness is less than 10 percent between links for three successive rate
intervals.
An alarm includes the following information:
● Line-card or SFM NPU unit and HiGig port-channel ID in the format: hg-port-channel slot slot/npu-id/hg-port
—channel-id
● Alarm: triggered or cleared
Examples of the system log messages triggered when the threshold for a HiGig link bundle/port channel is exceeded are:
● %STKUNIT0-M:CP %SWMGR-5-HG-BUNDLE_UNEVEN_DISTRIBUTION: Found uneven distribution in hg-port-
channel 0/5/0
● %STKUNIT0-M:CP %SWMGR-5-HG-BUNDLE_UNEVEN_DISTRIBUTION_ALARM_CLEAR: Uneven distribution in
hg-port-channel 0/5/0 got cleared
Guidelines for Monitoring HiGig Link-Bundles
Take the following considerations into account when you configure HiGig link-bundle monitoring on the backplane:
● By default, the capability to monitor the traffic distribution in a HiGig link bundle on a line-card or SFM NPU is disabled.
● Each line-card NPU uses a single HiGig link bundle for its backplane links to connect each SFM (spine) NPU. The convention
used to identify a HiGig link-bundle interface is: hg-port-channel slot/npu-id/0, where slot specifies the line-card slot
number (0–2), npu-id specifies the NPU ID number (0–3), and 0 specifies the HiGig port-channel ID which is always 0 on a
line-card NPU.
● Each SFM NPU uses a separate HiGig link bundle to connect to each line-card (leaf) NPU. The convention used to identify a
HiGig link-bundle interface is: hg-port-channel 0/npu-id/higig-port-channel-id, where 0 specifies the SFM slot number which
is always 0, npu-id specifies the NPU ID number (0–5), and higig-port-channel-id specifies the HiGig port-channel ID on an
SFM NPU (0–10).
● HiGig link-bundle monitoring starts only when:
○ You enable monitoring for a specified HiGig link bundle using the hg-link-bundle monitor command.
○ Bundle usage for egress traffic exceeds the threshold configured with the hg-link-bundle monitor trigger-
threshold command.
Alarms are generated only when link-bundle traffic levels are high. At low traffic levels, only one or two significant flows may
cause unevenness. However, uneven traffic distribution across links during low-traffic periods is not critical and does not
trigger an alarm.
● You can enable SNMP traps and syslog messages to be generated when an uneven traffic distribution is detected in a HiGig
link bundle.
● Traffic distribution in a HiGig link bundle is calculated as the bandwidth-weighted mean use of all links in the bundle. This
calculation is performed only on links that are up in their operational status.
● The rate interval used to poll traffic distribution in member links in a HiGig link bundle is user-configurable. The default polling
interval is 15 seconds.
● The trigger threshold specifies the percentage of total bundle bandwidth used to issue an alarm for uneven traffic
distribution. The default is 60 percent. When the mean link utilization is below this value, uneven link-bundle traffic is not
reported.
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Interfaces