01-12 VLAN Troubleshooting

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Quidway NetEngine40&80

Troubleshooting Contents

Issue 01 (2007-08-30) Huawei Technologies Proprietary i

Contents

12 VLAN Troubleshooting........................................................................................................12-1

12.1 Introduction to VLAN...............................................................................................................................12-2

12.1.1 Concepts of VLAN ............................................................... ........................................................... 12-2

12.1.2 Communications between VLANs...................................................................................................12-5

12.1.3 VLAN Aggregation..........................................................................................................................12-6

12.2 Troubleshooting of Port-Based VLAN Communications...................................................................... ....12-6

12.2.1 Networking Environments .............................................................. ................................................. 12-7

12.2.2 Configuration Notes.........................................................................................................................12-7

12.2.3 Diagnostic Flowchart................................................................... .................................................... 12-8

12.2.4 Troubleshooting Procedure ..................................................................... .........................................12-9

12.3 Troubleshooting VLAN Trunk................................................................ ................................................ 12-11

12.3.1 Networking Environments .............................................................. ............................................... 12-12

12.3.2 Configuration Notes.......................................................................................................................12-12

12.3.3 Diagnostic Flowchart................................................................... .................................................. 12-13

12.3.4 Troubleshooting Procedure ..................................................................... .......................................12-14

12.4 Troubleshooting VLAN Aggregation......................................................................................................12-16

12.4.1 Networking Environments .............................................................. ............................................... 12-16

12.4.2 Configuration Notes.......................................................................................................................12-17

12.4.3 Diagnostic Flowchart................................................................... .................................................. 12-18

12.4.4 Troubleshooting Procedure ..................................................................... .......................................12-18

12.5 Troubleshooting Cases .............................................................. .............................................................. 12-20

12.5.1 Failure to Add Ports to the VLAN ................................................................ .................................12-20

12.5.2 Failure to Delete a VLAN..............................................................................................................12-20

12.5.3 Failure to Configure the VLAN Interface ....................................................................... ...............12-21

12.5.4 Failure to Set the VLAN as a Super-VLAN................................................................................... 12-21

12.5.5 Failure to Add a VLAN to a Super-VLAN ........................................................... .........................12-22

12.5.6 Failure to Delete a VLAN from the Trunk Port ............................................................... ..............12-22

12.6 Diagnostic Tools......................................................................................................................................12-23

12.6.1 display Command ............................................................... ........................................................... 12-23

12.6.2 debugging Command............................................................. ........................................................ 12-23


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ii Huawei Technologies Proprietary Issue 01 (2007-08-30)

Figures

Figure 12-1Typical application of VLAN ................................................................. ......................................12-2

Figure 12-2VLAN frames defined by 802.1Q.................................................................................................12-3

Figure 12-3Differences of Access port, Trunk port and Hybrid port ............................................................... 12-4

Figure 12-4Implementation of communications between VLANs through a router .......................................12-5

Figure 12-5Implementation of communications between VLANs through VLANIF interfaces ....................12-6

Figure 12-6Networking diagram of configuring VLAN ......................................................... ........................12-7

Figure 12-7Fault diagnostic flowchart for troubleshooting of port-based VLAN communications................ 12-9

Figure 12-8Networking diagram of VLAN Trunk ........................................................................... .............12-12

Figure 12-9Diagnosis flow of VLAN Trunk faults ................................................................. ......................12-14

Figure 12-10Networking diagram of VLAN aggregation ........................................................................... ..12-16

Figure 12-11Diagnosis flow of VLAN aggregation faults ...................................................................... ......12-18


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Troubleshooting 12 VLAN Troubleshooting

Issue 01 (2007-08-30) Huawei Technologies Proprietary 12-1

12 VLAN TroubleshootingAbout This Chapter

The following table shows the contents of this chapter.

Section Description

12.1 Introduction to VLAN This section describes the basic knowledge about VLANtroubleshooting.

12.2 Troubleshooting of

Port-Based VLANCommunications

This section describes the basic knowledge abouttroubleshooting of port-based VLAN communications

12.3 Troubleshooting VLANTrunk

This section describes the basic knowledge abouttroubleshooting VLAN trunk

12.4 Troubleshooting VLANAggregation

This section describes the notes of VLAN aggregation,

the troubleshooting flowchart, and the troubleshootingprocedure for typical VLAN networking environments.

12.5 Troubleshooting Cases This section presents the actual troubleshooting cases.

12.6 Diagnostic Tools This section describes the diagnostic tools, including thedisplaycommand and the debugging command.


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12 VLAN Troubleshooting


Troubleshooting

12-2 Huawei Technologies Proprietary Issue 01 (2007-08-30)

12.1 Introduction to VLAN

12.1.1 Concepts of VLANThe VLAN technology solves the problem that the switch cannot restrict broadcast. VLAN is

used to divide a physical LAN into several broadcast domains. Each broadcast domain iscalled a VLAN. Hosts in the same VLAN can communicate with each other. Hosts in differentVLANs, however, cannot communicate with each other. In this way, broadcast packets are

limited within a VLAN.

Besides the dividing broadcast domains, VLAN can also satisfy complex network

applications.

For example, an office building is rent by some enterprises. The network cost will be veryhigh for the enterprises if they set up their respective LANs. However, if they share the same

LAN in the building, their information security cannot be guaranteed.

VLAN, however, can not only make the enterprises share the LAN but also guarantee theirinformation security.

Figure 12-1is a typical application of VLAN. Three switches are located in different sites and

different floors in a building. Each switch connects three PCs that belong to three VLANs(three enterprises). In Figure 12-1, each dashed-line block stands for a VLAN.

Figure 12-1Typical application of VLAN

VLAN-A

VLAN-B

VLAN-C

Router

Switch1 Switch2 Switch3

The NE40&80 supports the division of VLANs based on ports, that is, based on the port

number. Which VLAN the PC belongs to depends on the VLAN of the port to which the PC isattached.


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Format of VLAN Frames

In IEEE 802.1Q, the format of Ethernet frames is changed after you add a 4-byte 802.1Q tag

between the source MAC address field and the protocol type field. See Figure 12-2.

Figure 12-2VLAN frames defined by 802.1Q

Destination

Address

Source

Address

802.1Q Tag

Type

PRI/

CFI/

VID

Length/Type Data FCS

(CRC-32)

6 bytes 6 bytes 4 bytes 2 bytes 46-1517 bytes 4 bytes

The 802.1Q tag includes four fields as follows:

Type: stands for the type of the frame. It is of two bits. When its value is 0x8100, itmeans the frame is an 802.1Q frame. A device that does not support 802.1Q will discardsuch frames.

PRI: stands for the priority of the frame. It is of three bits. Its value is an integer in therange of 0 to 7. The filed is for QoS.

CFI: Canonical Format Indicator. It is of one bit. It indicates whether the MAC address isin the typical format. It is for the token ring network and FDDI.

VID: VLAN ID. It specifies to which VLAN the fame belongs. It is of 12 bits. In theVRP, VLAN ID 0 refers to the default VLAN.

Port Type

Some ports can identify VLAN frames defined by 802.1Q but some cannot.

Depending on whether they can identify VLAN frames, ports fall into four types: access port,Trunk port, Hybrid port and Q-in-Q port.

Figure 12-3lists the differences of Access port, Trunk port and Hybrid port.


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Figure 12-3Differences of Access port, Trunk port and Hybrid port

Port Type Identification of frames Allow taggedframes or not

Usage

Access port Only identifies Ethernetframes -

Connect the switch andPC.

Trunk port Can identify frames of

common VLAN and

default VLAN; can permitframes of multiple VLANs

Permit untagged

frames of default

VLAN. Frames ofother VLAN mustcarry tags

Connect switches.

Hybrid port Can identify frames of

common VLAN and

default VLAN; can permitframes of multiple VLANs

Permit both tagged

frames and untaggedframes

Connect the switch

with the network

composed by switchand computers.

The Q-in-Q port is a kind of port that runs the Q-in-Q protocol.

Principle of the Q-in-Q protocol: When users tagged packets enter the backbone network of the ISP,a new tag with a public VLAN ID is added to the packets. When the packets reach the PE device on

the other side of the network, the new tag is removed and the original user packets are recoveredbefore they are sent to the CE device. The packet transmitted in the backbone network has two

layers of 802.1Q tags (a public network tag and a private network tag). In this case, the protocol iscalled Q-in-Q protocol.

Customer Edge (CE): refers to the customer network edge device. It is directly connected with thenetwork of the Internet Service Provider (ISP).

Provider Edge (PE): refers to the ISP edge router. It is located at the edge of the ISPs network and isconnected directly with the CE device.

Processing of Frames on the Switch

The switch processes frames as the following three procedures:

1. Receiving frames

Frames received by the switch may be tagged VLAN frames, or untagged Ethernet frames.

When the switch receives a frame, it determines how to process the frame depending on thetype of the port through which the frame is received. It may process the frame in one of the

following ways:

Adding a new tag

Discarding

Continuing to process

2. Routing

The layer-2 switch searches VLAN configuration based on the destination MAC address and

VLAN ID of the frame. In this case, it can find the egress of the frame.

3. Sending frames

The switch sends out the frame onto network through the outbound port.


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You can configure the outbound port how to process the tag of a frame. For example, if thehosts, on the network segment connected to the outbound port of the frame, cannot identify802.1Q tags, you can set the port to remove the tag first before it sends out the frame. If the

outbound port is connected directly with other switches, you can set the port to send framesdirectly.

12.1.2 Communications between VLANs

Hosts in different VLANs cannot communicate with each other at the layer 2.

To implement communications between them, IP routes must be set up. There are twosolutions to carry out communications between VLANs.

The NE40 supports the following two solutions and the NE80 does not support the configuration of

VLANIF on the interface. You can choose it depending on the device.

Employing RoutersIn most cases, LAN is connected with the router through the Ethernet interface on the switch(switched Ethernet interface) and the Ethernet interface on the router (routed Ethernet

interface). See Figure 12-4.

Figure 12-4Implementation of communications between VLANs through a router

VLAN 2 VLAN 3

VLANTrunkSubinterface

Router

Switch

Access port

Suppose two VLANs, VLAN2 and VLAN3, have been set up on the switch. To carry outcommunications between VLAN2 and VLAN3, you need to create first two sub-interfaces

and configure 80.21 encapsulation and IP addresses for them on the connected Ethernetinterfaces of the router and the switch. Then set the type of connected Ethernet interfaces to

be Hybrid to allow frames of VLAN2 and VLAN3 to pass through the interface.

Configuring VLNAIF Interface on the Switch

If a switch supports IP routing, it can carry out communications between VLANs without the

router.


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As shown in Figure 12-5, two VLANs, VLAN2 and VLAN3 have been set up on the switch.To carry out communications between VLAN2 and VLAN3, you can create two VLANinterfaces on the switch and configure IP addresses and routes for them.

Figure 12-5Implementation of communications between VLANs through VLANIF interfaces

VLAN2 VLAN3

VLANIF VLANIF

Switch

After you configure a VLAN, you can create the VLAN interface with the interface vlanifcommand.The VLAN interface is a kind of virtual interface and has layer-3 features.

12.1.3 VLAN AggregationTo carry out communications between VLANs, you need to configure an IP address for each

VLAN interface to set up routes between the VLANs. This will consume many IP address

resources if there are many VLANs. VLAN aggregation solves this problem.

VLAN aggregation is to group multiple VLANs together to form a super-VLAN. Each VLAN

in the group (super-VLAN) is called a sub-VLAN.

Then you can create one VLAN interface only for the super-VLAN and set one IP address for

the VLAN interface, without having to set IP addresses for each sub-VLAN. In this case, allthe sub-VLANs in the super-VLAN share the same IP network segment. This improves the

usage efficiency of IP addresses.

For details of VLAN aggregation, see RFC 3069 (VLAN Aggregation for Efficient IP AddressAllocation).

12.2 Troubleshooting of Port-Based VLANCommunications

This section covers the following topics:

Networking Environments

Configuration Notes


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Diagnostic Flowchart

Troubleshooting Procedure

12.2.1 Networking Environments

Figure 12-6Networking diagram of configuring VLAN

VLAN2 VLAN3

VLANIF2

120.1.1.1/24

VLANIF3

130.1.1.1/24

GE1/0/0

GE2/0/0

GE3/0/0

GE4/0/0

12.2.2 Configuration Notes

Item Sub-item Description

Port Port switch Only a layer-2 port can be added to a VLAN. If it is alayer-3 port, you need to execute the portswitch

command first to switch the interface to a layer-2 port.

Before you switch it, there must not have anyconfigured service on the layer-3 interface.

VLAN Adding a port to

the VLAN

There are two ways:

In interface view, set the default VLAN of the portby using the port default vlancommand.

In the VLAN view, use the portcommand to add aport to the VLAN.

Creating aVLANIF interface

When creating a VLANIF interface, the correspondingVLAN must exist.

VLANIF

Configuring IPaddress

When configuring IP addresses for VLANIF interfaces,

note that the IP addresses of different VLANIFinterfaces must be on different network segments.

The following details the precautions by taking Figure 12-6as an example.

Step 1 Configure VLAN2.

# Switch the interface to a layer-2 port.


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Troubleshooting


[Quidway] interface gigabitethernet 1/0/0

[Quidway-GigabitEthernet1/0/0] portswitch

[Quidway-GigabitEthernet1/0/0] quit




# Create VLAN2.

[Quidway] vlan 2

# Add GE1/0/0 and GE2/0/0 to VLAN2.

[Quidway-vlan2]port gigabitethernet 1/0/0 2/0/0

[Quidway-vlan2]quit

# Configure the VLANIF interface.

[Quidway] interface vlanif 2

[Quidway-Vlanif2] ip address 120.1.1.1 24[Quidway-Vlanif2] quit

Step 2 Configure VLAN3

# Switch the interface to a layer-2 port.







# Create VLAN3.

[Quidway] vlan 3

# Add GE3/0/0 and GE4/0/0 to VLAN3.

[Quidway-vlan3] port gigabitethernet 3/0/0 4/0/0

[Quidway-vlan3] quit


[Quidway] interface vlanif 3

[Quidway-Vlanif3] ip address 130.1.1.1 24

[Quidway-Vlanif3] quit

----End

12.2.3 Diagnostic Flowchart

The diagnostic flowchart is shown in Figure 12-7.


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Figure 12-7Fault diagnostic flowchart for troubleshooting of port-based VLAN communications

Seek technical

support

Add the interface

to the VLAN

End

Fault rectified?

Check the network

cables, and restart

the interface

Fault rectified?

Restart the

VLANIF interfaceFault rectified?

Re-plan and

configure the

network segment

Fault rectified?

Fault rectified?

Yes

Yes

Yes

Yes

Yes

No

Yes

Yes

Yes

Yes

No

No

No

No

No

No

No

No

No

No

Is the

interface added to

the VLAN?

Is the

interface in theVLAN Up?

Is theVLANIF interface

Up?

Are the MACand ARP entries

learnt?

Is VLAN

network segementcorrect?

Interfaces in,

among VLANs

not interwork

Rectify the fault

by using the"ARPTroubleshooting"

12.2.4 Troubleshooting ProcedureThe steps of troubleshooting are as follows:

Step 1 Check that the interface has been added to the VLAN.

According to the networking plan, check that the specific port has been added to the specifiedVLAN. Devices in a same VLAN can communicate with each other through layer-2 port.

Different VLANs must use layer-3 interfaces to communicate with each other. Use thedisplay vlan vlanidcommand to check the ports in a VLAN.

[Quidway] display vlan 2

VLAN ID Type Status MAC Learning Broadcast

--------------------------------------------------------------------------2 common enable enable enable


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Troubleshooting


----------------

Untagged Port: Ethernet3/0/0

Step 2 Check that the interfaces in the VLAN are in Up state.

The link indicator of the Ethernet interface should be on. Otherwise, check the network cableand check the state of the interfaces in the VLAN. Use the display interfacecommand tocheck the state of the interface. For example:

[Quidway] display interface Ethernet 2/0/0

Ethernet2/0/0 current state: up

Hardware is WAN-FastEthernet,

Address is 00e0-fc17-ac14

Description: HUAWEI, Quidway Series, Ethernet2/0/0 Interface

The Maximum Transmit Unit is 1500 bytes, the BandWidth is 10000 Kbits

Send-frame-type is Ethernet_II, loopback not set

Negotiation enabled, half-duplex, 10Mbps, No trust 802.1p

This port works as a Switch

Statistics last cleared: neverTraffic statistics:

Last 5 minutes input rate 0 bytes/sec, 0 packets/sec

Last 5 minutes output rate 0 bytes/sec, 0 packets/sec

0 packets input, 0 bytes

0 packets output, 0 bytes

Input: 0 shorts, 0 jumbos, 0 giants, 0 pauses

0 unicasts, 0 multicasts, 0 broadcasts

0 MulticastOctets, 0 MulticastPkts

0 input fragments, 0 jabbers

0 CRC, 0 errors, 0 overruns

Output: 0 shorts, 0 jumbos, 0 giants



0 runts, 0 jabbers, 0 CRC

0 deferrals, 0 underruns, 0 aborts

0 collisions, 0 lates, 0 singles

0 multiples, 0 excessives

PVID is 2, port is hybrid port

MSTP configured to disable

Port priority is 0

Step 3 Check that the VLANIF interface is in Up state.

Firstly, check the IP address of the VLANIF interface. Then, check whether the VLANIFinterface is in shutdown state. If it is, enable it. After that, check that the correspondingVLAN is in shutdown state. If it is, enable it. In this case, if the interfaces in the VLAN are in

UP state, the VLANIF interface must be in UP state, too. Otherwise, contact Huawei technical

support engineers.

Check the state of the VLANIF interface as follows.

[Quidway] display interface Vlanif 2

Vlanif2 current state : UP

Line protocol current state : UP

Description : HUAWEI, Quidway Series, Vlanif2 Interface, Route Port

The Maximum Transmit Unit is 1500 bytes

Internet Address is 10.1.1.1/24

Hardware address is 00ff-6611-1234

Physical is VLANIF


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Troubleshooting



Figure 12-8Networking diagram of VLAN Trunk

RouterA

VLAN5 VLAN9

RouterB

GE1/0/0 GE1/0/0

VLAN5

VLAN9


Configurationitem

Sub-item Description

Port switch Only a layer-2 port can be added to a VLAN. If it is alayer-3 interface, you need to execute the portswitch

command first to switch the interface to a layer-2 port.Before you switch it, there must not have anyconfigured service on the layer-3 interface.

Port

Configuring

the VLANthat the Trunkport allows

Before configuring the Trunk port to permit the frames

of a VLAN, make sure that the Trunk port has beenadded to the VLAN. The VLAN interface cannot beconfigured with IP address.

VLAN Adding a port

to the VLAN

There are two ways:

In the interface view, set the default VLAN of the

port by using the port default vlancommand.

In the VLAN view, use the portcommand to add aport to the VLAN.

Step 1 Configure Router A.

# Create VLANs. Add port Eth2/0/0 to VLAN5 and port Eth3/0/0 to VLAN9.

[RouterA] vlan 5

[RouterA-vlan5] port ethernet 2/0/0

[RouterA-vlan5] quit

[RouterA] vlan 9

[RouterA-vlan9] port ethernet 3/0/0

[RouterA-vlan9] quit


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# Set the switched interface GE1/0/0 as a VLAN Trunk port and set it to allow the packets of

the VLAN 5 and the VLAN 9 to pass.

[RouterA] interface gigabitethernet 1/0/0

[RouterA-GigabitEthernet1/0/0] portswitch

[RouterA-GigabitEthernet1/0/0] port trunk allow-pass vlan 5 9[RouterA-GigabitEthernet1/0/0] quit

Step 2 Configure Router B

# Create VLANs. Add port Eth2/0/0 to VLAN5 and port Eth3/0/0 to VLAN9.

[RouterB] vlan 5

[RouterB-vlan5] port ethernet 2/0/0

[RouterB-vlan5] quit

[RouterB] vlan 9

[RouterB-vlan9] port ethernet 3/0/0

[RouterB-vlan9] quit

# Set the switched interface GE1/0/0 as a VLAN Trunk port and set it to allow frames ofVLAN5 and VLAN9 to pass.

[RouterB] interface gigabitethernet 1/0/0

[RouterB-GigabitEthernet1/0/0] portswitch

[RouterB-GigabitEthernet1/0/0] port trunk allow-pass vlan 5 9

[RouterB-GigabitEthernet1/0/0] quit

----End




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Troubleshooting


Figure 12-9Diagnosis flow of VLAN Trunk faults

Seek technicalsupport

Add the interfaceto the sub-VLAN

End

Fault rectified?

Fault rectified?

Add the sub-VLAN

to the super-VLANFault rectified?

Reconfigure the

trunk at both endsFault rectified?

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

No

No

No

No

No

No

No

No

Is theinterface added to

sub-VLAN?

Is the

interface in the sub-VLAN Up?

Is the

sub-VLAN added to

super-VLAN?

Is the

VLANIF interface

Up?

Recitify the faultbased on the "ARP

Troubleshooting"

Fault rectified?

Yes

No

No

Are the MACand ARP entries

learnt?

Yes

Interfaces in

the VLAN cannot

access the public

network

Check the cables,and the interface is

shut down

12.3.4 Troubleshooting ProcedureThe steps of troubleshooting are as follows:


According to the networking plan, check that the specific port has been added to the specified

VLAN. Devices in a same VLAN can communicate with each other through layer-2 port.Different VLANs must use layer-3 interfaces to communicate with each other. Use the

display vlan vlanidcommand to check the ports in a VLAN.



--------------------------------------------------------------------------

2 common enable enable enable


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----------------


----------------

Tagged Port: GigabitEthernet1/0/0

Step 2 Check that the interfaces in the VLAN are in Up state.

The Link indicator of the Ethernet interface must be on. Otherwise, check the network cable

and check the state of the interfaces in the VLAN. Use the display interfacecommand tocheck the state of the interface. For example:

[Quidway] display interface Ethernet 2/0/0

Ethernet2/0/0 current state: up

Hardware is WAN-FastEthernet,

Address is 00e0-fc17-ac14

Description: HUAWEI, Quidway Series, Ethernet2/0/0 Interface

The Maximum Transmit Unit is 1500 bytes, the BandWidth is 10000 Kbits

Send-frame-type is Ethernet_II, loopback not set

Negotiation enabled, half-duplex, 10Mbps, No trust 802.1pThis port works as a Switch

Statistics last cleared: never

Traffic statistics:

Last 5 minutes input rate 0 bytes/sec, 0 packets/sec

Last 5 minutes output rate 0 bytes/sec, 0 packets/sec

0 packets input, 0 bytes

0 packets output, 0 bytes

Input: 0 shorts, 0 jumbos, 0 giants, 0 pauses



0 input fragments, 0 jabbers

0 CRC, 0 errors, 0 overruns

Output: 0 shorts, 0 jumbos, 0 giants



0 runts, 0 jabbers, 0 CRC

0 deferrals, 0 underruns, 0 aborts

0 collisions, 0 lates, 0 singles

0 multiples, 0 excessives

PVID is 2, port is hybrid port

MSTP configured to disable

Port priority is 0

The display shows that the interface in the VLAN is in UP state.

Step 3 Check that trunk VLAN has been configured between routers.

Check the ports in the VLAN. The connected interfaces between the routes are in the tagged

port list.



--------------------------------------------------------------------------


----------------


----------------

Tagged Port: GigabitEthernet1/0/0


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Troubleshooting


The display shows that the router has been configured with the Trunk VLAN interface.

Step 4 Check that the interface can learn MAC and ARP entries.

Use the display mac-address dynamiccommand to check the learnt dynamic MAC entries

and use the display arp dynamiccommand to check the learnt dynamic ARP entries. If thelearnt entries are incorrect or have not been learnt, see the ARP Troubleshooting.

If the trouble still exists at this time, contact the Huawei technology engineer or access

http://support.huawei.com.

----End

12.4 Troubleshooting VLAN Aggregation

This section covers the following topics:

Networking Environments

Configuration Notes

Diagnostic Flowchart



Figure 12-10Networking diagram of VLAN aggregation

VLAN2 VLAN3

VLAN4


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Configuration Notes

Item Sub-item Description

Port Port switch Only a layer-2 port can be added to a VLAN. If it is a

layer-3 interface, you need to execute the portswitchcommand first to switch the interface to a layer-2 port.

Before you switch it, there must not have anyconfigured service on the layer-3 interface.

Create sub-VLAN By default, the newly created VLAN is sub-VLAN.

When configuring a sub-VLAN, you only need to addports to the created VLAN. Do not configure IP

address of other layer-3 attributes on sub-VLAN

interfaces.

Add a port to theVLAN

There are two ways:

In the interface view, set the default VLAN of the

port by using the port default vlancommand.

In the VLAN view, use the portcommand to add a

port to the VLAN.

Createsuper-VLAN

The super-VLAN and the sub-VLAN must use

different VLAN IDs. Besides, the super-VLAN shouldcontain no physical port.

VLAN

Add a sub-VLAN

to the super-VLAN

Only sub-VLAN can be added to the super-VLAN.

Create a VLANIF

interface

When creating a VLANIF interface, the corresponding

VLAN must exist and is a super-VLAN.

VLANIF

Configure IP

addresses

When configuring IP addresses for VLANIF interfaces,

note that the IP addresses of different VLANIFinterfaces must be on different network segments.


# Configure sub-VLANs VLAN2 and VLAN3. Add interfaces to the sub-VLAN.

Omitted.

# Configure a super-VLAN.

[Quidway] vlan 4

[Quidway-vlan4] aggregate-vlan

[Quidway-vlan4] access-vlan 2 to 3


[Quidway]interface Vlanif 4

[Quidway-Vlanif4]ip address 10.1.1.1 24


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Troubleshooting




Figure 12-11Diagnosis flow of VLAN aggregation faults

Seek technicalsupport

Add the interface to

the sub-VLAN

End

Fault rectified?

Fault rectified?

Add the sub-VLAN

to the super-VLANFault rectified?

Restart theVLANIF interface Fault rectified?

Fault rectified?

Yes

Yes

Yes

Yes

Yes

No

Yes

Yes

Yes

Yes

No

No

No

No

No

No

No

No

No

No

Is the

interface added to

sub-VLAN?

Is theinterface in the

sub-VLAN Up?

Is the

sub-VLAN added to

super-VLAN?

Are the MAC

and ARP entrieslearnt?

Is the

VLANIF interfaceUp?

Rectify the fault

based on the"ARP

Troubleshooting"

Interfaces ina VLAN cannot

access the public

network

Check the cables,

and the interface

is shutdown

12.4.4 Troubleshooting Procedure

The steps of troubleshooting are as follows:


According to the networking plan, check that the specific port has been added to the specifiedsub-VLAN. Devices in a same VLAN can communicate with each other through layer-2 port.

Different VLANs must use layer-3 interfaces to communicate with each other. Use the

display vlan vlanidcommand to check the ports in a VLAN.


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Step 2 Check that the interfaces in the sub-VLAN are in Up state.

For detailed steps, see Check that the interfaces in the VLAN are in Up state.

Step 3 Check that the sub-VLAN has been added to the specified super-VLAN.

Use the display vlancommand to check that the sub-VLAN exists.



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4 super enable enable enable

---------------

sub-VLAN List: 2-3

View the displayed information. If the super-VLAN does not contain the wanted sub-VLAN,

add the sub-VLAN to the super-VLAN.

Step 4 Check the corresponding VLANIF interface of the super-VLAN.

Check that the VLANIF interface is in up state and that the IP address of the VLANIF

interface has been properly configured.

[Quidway] display interface vlanif 3

Vlanif3 current state : UP

Line protocol current state : UP

Description : HUAWEI, Quidway Series, Vlanif3 Interface, Route Port

The Maximum Transmit Unit is 1500 bytes

Internet Address is 10.1.1.1/24

IP Sending Frames' Format is PKTFMT_ETHNT_2, Hardware address is 00e0-271e-f652

Physical is VLANIF

5 minutes input rate 0 bytes/sec, 0 packets/sec

5 minutes output rate 0 bytes/sec, 0 packets/sec

0 packets input, 0 bytes, 0 drops

0 packets output, 0 bytes, 0 drops

From the display, you can check that state and network segment of the VLANIF interface are

correct. If they are incorrect, correct them according to Check that the VLANIF interface is in

Up state.

Step 5 Check that the interface can learn MAC and ARP entries.

Use the display mac-address dynamiccommand to check the learnt dynamic MAC entries

and use the display arp dynamiccommand to check the learnt dynamic ARP entries. If theentries have not been learnt and the learnt entries are incorrect, see the ARP Troubleshooting.

If the trouble still exists at this time, contact the Huawei technology engineer or access

http://support.huawei.com.

----End


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Troubleshooting


12.5 Troubleshooting Cases

12.5.1 Failure to Add Ports to the VLAN

Fault Symptom

Fail to add a port to the VLAN.

Fault Analysis

The possible causes are:

The port does not exist.

The specified VLAN is a super-VLAN.

The port has been added to the Trunk interface.

The port is a routed port.


Step Action

1 Check that the port exists and the command line is input correctly.

2 Use the command to confirm that the default VLAN ID of the interface does notbelong to other VLAN.

3 Use the display vlancommand to check that the VLAN is not a super-VLAN. Thesuper-VLAN must contain no physical port.

4 In the interface view, use the display thiscommand to check the configuration of

the port. Ensure that the port has not been added to any Trunk interface.

5 Use the display interfacecommand to check that the port is a switched port.

12.5.2 Failure to Delete a VLAN

Fault Symptom

Fail to delete a VLAN.

Fault Analysis


The specified VLAN does not exist.

The VLAN has a VLAN interface created.


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Step Action

1 Use the display vlancommand to check that the specified VLAN exists.

2 Use the display interface vlanifcommand to check that the VLAN has an existing

VLAN interface. If the VLAN interface exists, delete it.

12.5.3 Failure to Configure the VLAN Interface

Fault Description

Configuring the VLAN interface fails.

Fault Analysis


The VLAN has not been created.

The specified VLAN is s sub-VLAN.


Step Action

1 Use the display interface vlanifcommand to check that the specified VLAN has

been created.

2 Use the display vlan vlan-idcommand to check that the VLAN is a sub-VLAN.

12.5.4 Failure to Set the VLAN as a Super-VLAN

Fault Symptom

Fail to set the VLAN as a super-VLAN.

Fault Analysis

The reason may be:

VLAN contains the physical ports.

The specified VLAN is sub-VLAN.


Step Action

1 Use the display vlan vlan-idcommand to check whether the VLAN contains

physical port. If so, delete the physical port.


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12.6 Diagnostic Tools

12.6.1 display Command

Command Description

displayvlan Display information of a VLAN.

displayportallow-vlan Display the VLANs allowed by the port.

display interface vlanif Display the information of the VLAN interfaces.

12.6.2 debugging Command

Command Description

debugging vlan packet Debug VLAN packets.

01-12 VLAN Troubleshooting

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