44
−
Execute
the
display this
command in Ethernet interface view to verify that the
ip
source binding
or
ip verify source
command is configured on the port. To display
source guard binding entries, execute the
display ip source binding
or
display ipv6
source binding
command. If IP source guard is configured but the packets match no
entry, further troubleshoot the problem based on the way the binding entries are created.
−
Determine whether the port is configured with the portal authentication. Packets of users
that fail to pass the portal authentication will be dropped by the port. Use the
display
portal interface
command to display the portal configuration information of the
specified VLAN interface. Determine whether the portal authentication can be disabled
based on the network conditions. To disable the portal authentication at Layer 3, use the
undo portal server server-name
command in VLAN interface view of the VLAN to
which the port belongs.
−
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.
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. As a best
practice, disable STP on the port or configure 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.
−
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.
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.
