330CHAPTER 21: CONFIGURING IP APPLICATION

Figure 122 Format of VLAN tag

 

 

 

Byte 1

 

 

 

 

 

 

Byte 2

 

 

 

 

 

 

Byte 3

 

 

 

 

 

Byte 4

 

 

 

1

 

 

TPID(Tag Protocol Identifier)

 

 

 

 

 

 

 

 

TCI(Tag Control Information)

 

 

 

 

 

0

0

0

0

0

0

1

0

0

0

0

0

0

0

0

Priority

 

*

 

 

 

 

VLAN ID

 

 

 

 

 

7

6

5

4

3

2

1

0

7

6

5

4

3

2

1

0

7

6

5

4

3

2

1

0

7

6

5

4

3

2

1

0

TPID (Tag Protocol Identifier) field has two bytes. When its value is 0X8100, it means the Ethernet frame header contains VLAN tag. The third and fourth byte are TCI (Tag Control Information) fields, with the higher three bits being user priority field, the fourth being the instruction of standard encapsulation format and the other 12 bits being VLAN IDs whose value ranges from 0 to 4094 (the value must begin with 1 on routers).

Configure VLAN VLAN Configuration includes:

■Create Ethernet subinterface.

■Specify the VLAN to which Ethernet subinterface belongs.

■Configure IP address of Ethernet subinterface.

1Create Ethernet subinterface

Among the VLAN configuration tasks of the 3Com Router series, Ethernet subinterface should first be created and then other functions are to be configured. After deleting Ethernet subinterface, the original interface parameters will be invalidated.

Please implement the following configuration under the system view.

Table 362 Create Ethernet subinterface

Operation

Command

 

 

Create Ethernet subinterface and enter

interface ethernet

Ethernet subinterface view

interface-number.subinterface-number

 

 

Delete specified Ethernet subinterface

undo interface ethernet

 

interface-number.subinterface-number

 

 

By default, Ethernet subinterface is not created.

2Specify the VLAN on which Ethernet subinterface is located

In order to enable a certain Ethernet subinterface to receive and transmit VLAN message, it is necessary to specify to which VLAN the subinterface belongs, i.e., to specify the ID number of the VLAN.

Please implement the following configuration under Ethernet subinterface view.

Table 363 Specify the VLAN on which Ethernet subinterface is located

Operation

Command

 

 

Specify the VLAN on which Ethernet

vlan-type dot1q vid vlan-id

subinterface is located

 

 

 

Remove the specification for the

undo vlan-type

belonging of the Ethernet subinterface

 

 

 

By default, Ethernet subinterface does not specify VLAN ID.

It must be noted that if VLAN ID is not specified for the created Ethernet subinterface, the Ethernet subinterface can only carry IPX data, but cannot configure IP address to carry IP data.

3Configure IP address of Ethernet subinterface

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3Com 10014299 Create Ethernet subinterface, Specify the Vlan on which Ethernet subinterface is located, Undo vlan-type
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