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# Creating a VLAN Subinterface

Ethernet interfaces support IP, PPPoE, MPLS, or both IP and PPPoE on each VLAN. In addition to a VLAN major interface level, a VLAN subinterface level distinguishes the VLAN.

| Note: You cannot configure VLANs on the Fast Ethernet port of the SRP module.

Tasks to configure VLAN subinterface are:

- Creating a VLAN Major Interface
- Configuring IP over VLAN
- Configuring PPPoE over VLAN
- Configuring MPLS over VLAN
- Configuring IP over VLAN and PPPoE over VLAN

## Creating a VLAN Major Interface

To use VLANs, you must first configure the Ethernet interface for VLAN encapsulation. This creates the VLAN major interface. For example:

1. Specify a Fast Ethernet, Gigabit Ethernet, or 10-Gigabit Ethernet port.
   `
   host1(config)#interface fastEthernet 4/0
   `
2. Specify VLAN as the encapsulation method.
   `
   host1(config-if)#encapsulation vlan
   `

   The router creates the VLAN major interface.

You can now create multiple VLAN subinterfaces to carry higher-level protocols. For examples, see Creating a VLAN Subinterface, next.

## Configuring IP over VLAN

To configure IP over VLAN over an Ethernet interface:

1. Specify a Fast Ethernet, Gigabit Ethernet, or 10-Gigabit Ethernet port.
   `
   host1(config)#interface fastEthernet 4/0
   `
2. Specify VLAN as the encapsulation method.
   `
   host1(config-if)#encapsulation vlan
   `

   The VLAN major interface is added.

3. Create a VLAN subinterface by adding a subinterface number to the interface identification command.
   `
   host1(config-if)#interface fastEthernet 4/0.3
   `
4. Do one of the following:
   1. Assign a VLAN ID for the subinterface.
      `
      host1(config-if)#vlan id 201
      `
   2. Assign a VLAN ID and the optional unique MAC address for the subinterface.
      `
      host1(config-if)#vlan id 201 mac-address 0090.1a01.1234
      `
5. Assign an IP address and mask.
   `
   host1(config-if)#ip address 192.6.129.5 255.255.255.0
   `
6. (Optional) Configure additional VLAN subinterfaces by completing Steps 3 through 5.

Figure 14 illustrates the IP/VLAN/Fast Ethernet stacking, showing two separate VLAN subinterfaces. Configure one VLAN subinterface entirely; then configure the next VLAN subinterface.

Figure 14: Example of IP/VLAN/Fast Ethernet Stacking Configuration Procedure

## Configuring PPPoE over VLAN

To configure PPPoE over VLAN over an Ethernet interface:

1. Specify a Fast Ethernet, Gigabit Ethernet, or 10-Gigabit Ethernet port.
   `
   host1(config)#interface fastEthernet 4/1
   `
2. Specify VLAN as the encapsulation method.
   `
   host1(config-if)#encapsulation vlan
   `

   The VLAN major interface is added.

3. Create a VLAN subinterface by adding a subinterface number to the interface identification command.
   `
   host1(config-if)#interface fastEthernet 4/1.1
   `
4. Do one of the following:
   - Assign a VLAN ID for the subinterface.
     `
     host1(config-if)#vlan id 201
     `
   - Assign a VLAN ID and the optional unique MAC address for the subinterface.
     `
     host1(config-if)#vlan id 201 mac-address 0090.1a01.1234
     `
5. Specify PPPoE as the encapsulation method on the interface.
   `
   host1(config-if)#pppoe
   `
6. Create a PPPoE subinterface.
   `
   host1(config-if)#pppoe subinterface fastEthernet 4/1.1.1
   `
7. Specify PPP as the encapsulation method on the interface.
   `
   host1(config-if)#encapsulation ppp
   `
8. Assign an IP address and mask.
   `
   host1(config-if)#ip address 192.6.129.5 255.255.255.0
   `
9. (Optional) Configure additional VLAN subinterfaces by completing Steps 3 through 8.

Figure 15 illustrates the PPPoE/VLAN/Fast Ethernet stacking, showing two separate VLAN subinterfaces. One VLAN subinterface has two PPPoE subinterfaces, and one VLAN subinterface has one PPPoE subinterface.

Figure 15: Example of PPPoE/VLAN/Fast Ethernet Stacking Configuration Procedure

## Configuring MPLS over VLAN

To configure MPLS over VLAN over an Ethernet interface:

1. Specify a Fast Ethernet, Gigabit Ethernet, or 10-Gigabit Ethernet port.
   `
   host1(config)#interface fastEthernet 4/0
   `
2. Specify VLAN as the encapsulation method.
   `
   host1(config-if)#encapsulation vlan
   `

   The VLAN major interface is added.

3. Create a VLAN subinterface by adding a subinterface number to the interface identification command.
   `
   host1(config-if)#interface fastEthernet 4/1.1
   `
4. Do one of the following:
   - Assign a VLAN ID for the subinterface.
     `
     host1(config-if)#vlan id 400
     `
   - Assign a VLAN ID and the optional unique MAC address for the subinterface.
     `
     host1(config-if)#vlan id 400 mac-address 0090.1a01.1234
     `
5. Enable MPLS on the interface.
   `
   host1(config-if)#mpls
   `

Figure 16 illustrates the MPLS/VLAN/Fast Ethernet stacking, showing one VLAN subinterface.

Figure 16: Example of MPLS/VLAN/Fast Ethernet Stacking Configuration Procedure

## Configuring IP over VLAN and PPPoE over VLAN

To configure IP over VLAN with PPPoE over the same VLAN over an Ethernet interface:

1. Specify a Fast Ethernet, Gigabit Ethernet, or 10-Gigabit Ethernet port.
   `
   host1(config)#interface fastEthernet 4/1
   `
2. Specify VLAN as the encapsulation method.
   `
   host1(config-if)#encapsulation vlan
   `

   The VLAN major interface is added.

3. Create a VLAN subinterface by adding a subinterface number to the interface identification command.
   `
   host1(config-if)#interface fastEthernet 4/1.1
   `
4. Do one of the following:
   - Assign a VLAN ID for the subinterface.
     `
     host1(config-if)#vlan id 400
     `
   - Assign a VLAN ID and the optional unique MAC address for the subinterface.
     `
     host1(config-if)#vlan id 400 mac-address 0090.1a01.1234
     `
5. Create an IP interface on the same VLAN as the PPPoE interface.
   `
   host1(config-if)#ip address 164.10.6.71 255.255.255.0
   `
6. Specify PPPoE as the encapsulation method on the interface.
   `
   host1(config-if)#pppoe
   `
7. Create a PPPoE subinterface.
   `
   host1(config-if)#pppoe subinterface fastEthernet 4/1.1.1
   `
8. Specify PPP as the encapsulation method on the interface.
   `
   host1(config-if)#encapsulation ppp
   `
9. Assign an IP address and mask.
   `
   host1(config-if)#ip address 192.6.129.5 255.255.255.0
   `
10. (Optional) Configure additional PPPoE subinterfaces by completing Steps 7 through 9 using unique numbering.

To configure additional IP interfaces over the VLAN major interface:

1. Create a new VLAN subinterface by adding a unique subinterface number to the interface identification command.
   `
   host1(config-if)#interface fastEthernet 4/1.2
   `
2. Assign a VLAN ID for the subinterface.
   `
   host1(config-if)#vlan id 401
   `
3. Assign an IP address and mask.
   `
   host1(config-if)#ip address 164.10.6.51 255.255.255.0
   `

Figure 17 illustrates the configuration steps for two VLAN subinterfaces. In this example:

- VLAN subinterface 4/1.1 has an IP interface, a PPPoE interface, and multiple PPPoE subinterface stacks.
- VLAN subinterface 4/1.2 has only an IP interface.

  | Note: Before you can remove a VLAN subinterface, you must remove the upper-layer interface stack.

  Figure 17: Example of PPPoE over VLAN with IP over VLAN Stacking Configuration Procedure

encapsulation ppp

- Use to configure PPP as the encapsulation method for the interface.
- Example
  `
  host1(config-if)#encapsulation ppp
  `
- Use the no version to disable PPP on the interface.
- See encapsulation ppp.

encapsulation vlan

- Use to configure VLAN as the encapsulation method for the interface.
- Example
  `
  host1(config-if)#encapsulation vlan
  `
- Use the no version to disable VLAN on an interface.
- See encapsulation vlan.

ip address

- Use to set a primary or secondary IP address for an interface or subinterface.
- Specify the layer 2 encapsulation before you set the IP address.
- Example
  `
  host1(config-if)#ip address 192.6.129.5 255.255.255.0
  `
- Use the no version to remove an IP address or disable IP processing.
- See ip address.

pppoe

- Use to configure PPPoE as the encapsulation method on the interface.
- Example
  `
  host1(config-if)#pppoe
  `
- Use the no version to disable PPPoE on the interface.
- See pppoe.

pppoe subinterface fastEthernet

- Use to create a PPPoE subinterface on a Fast Ethernet interface.
- Example
  `
  host1(config-if)#pppoe subinterface fastEthernet 4/1.1.1
  `
- Use the no version to remove a PPPoE subinterface on a Fast Ethernet interface.
- See pppoe subinterface.

pppoe subinterface gigabitEthernet

pppoe subinterface tenGigabitEthernet

- Use to create a PPPoE subinterface on a Gigabit Ethernet interface or on a 10-Gigabit Ethernet interface.
- Example 1—Creates a PPPoE subinterface on an ERX-7xx model, ERX-14xx model, or the ERX-310 router
  `
  host1(config-if)#pppoe subinterface gigabitEthernet 4/2.1.1
  `
- Example 2—Creates a PPPoE subinterface on the E320 router
  `
  host1(config-if)#pppoe subinterface tenGigabitEthernet 4/0/2.1.1
  `
- Use the no version to remove a PPPoE subinterface on a Gigabit Ethernet interface or on a 10-Gigabit Ethernet interface.
- See pppoe subinterface.

vlan description

- Use to assign an alias or description to a VLAN subinterface.
- You can use a maximum of 64 characters for the description or to name the alias.
- Example
  `
  host1(config-if)#vlan description randolph56a
  `
- Use the no version to remove the VLAN description.
- See vlan description.

vlan id

- Use to specify the VLAN ID.
- Use a VLAN ID that is in the range 0–4095 and is unique within the Ethernet interface.
- Issue the vlan id command before any upper bindings are made, such as IP or PPPoE.
- Use the mac-address keyword to specify a unique MAC address for the VLAN subinterface. When you do not specify a unique MAC address, the VLAN uses the MAC address of the Ethernet interface.
- Use the optional keyword untagged to specify that frames be sent untagged. The keyword is valid only for VLAN ID 0. Tagged frames can be received, but untagged frames are sent.
- Examples
  `
  host1(config-if)#vlan id 400
  host1(config-if)#vlan id 4 255 mac-address 0090.1a01.1234
  `
- There is no no version.
- See vlan id.

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