This section
describes the troubleshooting flowchart and provides a step-by-step
troubleshooting procedure to use when users cannot communicate after VLAN
mapping is configured.
Common Causes
As shown in
Figure 1, users in VLAN 6 need to communicate with users in VLAN 5 over
an ISP network.
The carrier assigns VLAN 10 as the stack VLAN (S-VLAN). Single-tag VLAN mapping
is configured on GE0/0/1 of SwitchC and SwitchD to map customer VLANs (CVLANs) 5
and 6 to S-VLAN 10.
After VLAN
mapping is configured on the interfaces, users in different VLANs cannot
communicate with
each other. This fault is commonly caused by one of the following:
1 The translated
VLAN (specified by map-vlan) has not been created.
2 The interfaces
configured with VLAN mapping are not added to the translated VLAN.
3 The translated
VLAN ID configured on SwitchC and SwitchD is different from the SVLAN ID
assigned by the carrier.
4 The interfaces
configured with VLAN mapping are faulty.
Troubleshooting Procedure
NOTE
Saving
the results of each troubleshooting step is recommended. If troubleshooting
fails to correct the fault, you will have a record of your actions to provide
Huawei technical support personnel.
Procedure
Step 1 Check that the translated VLAN (specified by map-vlan) has been created.
Run the display
vlan command on SwitchC and SwitchD to check whether the translated VLAN has
been created.
l If the
translated VLAN has not been created, run the vlan command to create it.
l If the
translated VLAN has been created, go to step 2.
Step 2 Check that the interfaces configured with VLAN mapping have been added
to the translated VLAN in tagged mode.
Run the display
this command on the interfaces configured with VLAN mapping to check
whether the
interfaces have been added to the translated VLAN in tagged mode.
NOTE
1 VLAN mapping
can only be configured on a trunk or hybrid interface, and the interface must
be added to the translated VLAN in tagged mode.
2 If a range of
original VLANs is specified by vlan-id1 to vlan-id2 on an interface, the
interface must be added to all the original VLANs in tagged mode, and the
translated VLAN cannot have a VLANIF interface.
3 Limiting MAC
address learning on an interface may affect N:1 VLAN mapping on the interface.
4 If the
interfaces configured with VLAN mapping have not been added to the translated
VLAN in tagged
mode, run the port trunk allow-pass vlan or port hybrid tagged vlan
command in the
interface views to add the interfaces to the translated VLAN in tagged
mode.
5 If the
interfaces have been added to the translated VLAN in tagged mode, go to step 3.
Step 3 Check that the translated VLAN ID configured on SwitchC and SwitchD is
the same as the SVLAN ID assigned by the carrier.
Run the display
this command on the interfaces configured with VLAN mapping to check
whether the
translated VLAN ID is the same as the S-VLAN ID assigned by the carrier.
If the translated
VLAN ID on an interface is different from the S-VLAN ID assigned by
the carrier, run
the undo port vlan-mapping vlan command on the interface to delete the
VLAN mapping
configuration, and then run the port vlan-mapping vlan command to set
the translated
VLAN ID to the S-VLAN ID.
If the translated
VLAN ID is the same as the S-VLAN ID assigned by the carrier, go to
step 4.
Step 4 Check that the user-side interfaces are in the C-VLANs.
Run the display
vlan vlan-id command on SwitchA and SwitchB to check whether the userside interfaces
are in the C-VLANs.
1 If the
user-side interfaces are not in the C-VLANs, run the port trunk allow-pass
vlan,
port hybrid
tagged vlan, or port default vlan command to add the interfaces to the CVLANs.
2 If the
user-side interfaces are in the C-VLANs, go to step 5.
Step 5 Collect the following information and contact Huawei technical support
personnel.
1 Results of the
preceding troubleshooting procedure
2 Configuration files, log files, and
alarm files of the Switches
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