Configuring VLAN Subinterfaces

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 subinterfaces are:

Creating a VLAN Major Interface

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

You can now create multiple VLAN subinterfaces to carry higher-level protocols. For examples, see Configuring VLAN Subinterfaces, 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 1 illustrates the IP/VLAN/Fast Ethernet stacking, showing two separate VLAN subinterfaces. Configure one VLAN subinterface entirely; then configure the next VLAN subinterface.

Figure 1: 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 2 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 2: 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 3 illustrates the MPLS/VLAN/Fast Ethernet stacking, showing one VLAN subinterface.

Figure 3: 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 4 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 4: Example of PPPoE over VLAN with IP over VLAN Stacking Configuration Procedure