Related Commands - HP 5920 series Troubleshooting Manual

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3. Verify that the port is not blocked:
Execute the display stp brief command to verify that STP does not set the state of the port to
discarding. When the port is in discarding state, it cannot forward traffic. HP recommends
disabling STP on the port, or configuring the port as an edge port if the port is connected to a
terminal device.
If the port belongs to an aggregation group, execute the display link-aggregation verbose
command to identify the port status. When the port is an Unselected port, it cannot forward
traffic. Locate the reasons why the port is in Unselected state. For example, the attribute
configurations of the port are different from the configurations of the reference port.
Identify whether the port is blocked by smart link. Use the display smart-link group command
to view the port status. If the state of the port is STANDBY or DOWN, the port cannot forward
traffic.
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4. Examine the following configurations that might cause packet loss:
VLAN configuration—Execute the display this command in Ethernet interface view to verify that
the port is in the VLAN of the packets. If it is not, add the port to the VLAN.
Blackhole MAC address entries—Execute the display mac-address blackhole command to
display blackhole MAC address entries. If the packets are discarded because they match a
blackhole MAC address entry, delete the entry. To delete the blackhole MAC address entry,
execute the undo mac-address blackhole mac-address vlan vlan-id command.
Rate limit—Execute the display qos lr interface command to display the rate limit configuration
on the port. If rate limit is configured on the port, make sure the committed information rate (CIR)
and the committed burst size (CBS) are appropriate. To adjust the CIR and CBS values, execute
the qos lr { inbound | outbound } cir committed-information-rate [ cbs committed-burst-size ]
command.
Storm suppression—Execute the display this command in Ethernet interface view to display the
configuration of storm suppression. Storm suppression includes broadcast suppression,
multicast suppression, and unknown unicast suppression. To adjust the suppression thresholds,
execute the broadcast-suppression, multicast-suppression, and unicast-suppression
commands, respectively.
5. Verify that no congestion occurs by using the display qos queue-statistics interface command.
If congestion occurs, locate and resolve the problem by referencing related congestion
management documents.
6. If the problem persists, contact HP Support.

Related commands

This section lists the commands that you might use for troubleshooting Layer 2 packet loss failure.
Determine whether MFF is configured on the VLAN to which the port belongs. Use the
display mac-forced-forwarding vlan command to display the MFF information of the
specified VLAN. If no gateway information is displayed in the output, verify that ARP
snooping or DHCP snooping is correctly configured based on the MFF operation mode.
If the state of the port is DOWN, locate the reason for the port to be down. The possible
reasons include: its uplink device is configured with monitor link, the link of the port fails, or
the port is shut down. Further troubleshoot the problem based on the reason for the port to
be down.
If the state of the port is STANDBY, perform an active/standby switchover in the smart link
group.
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