Configuring S-VLAN Tunnels for Layer 2 Services over MPLS

When you configure Ethernet layer 2 services over MPLS, you can create a special type of S-VLAN called an S-VLAN tunnel that uses a single interface to tunnel traffic from multiple VLANs across an MPLS network. The S-VLAN tunnel enables multiple VLANs, each configured with a unique VLAN ID tag, to share a common S-VLAN ID tag when they traverse an MPLS network.

Advantages

Using S-VLAN tunnels provides an easier and faster way to configure Ethernet layer 2 services over MPLS than using standard S-VLANs. For example, consider the network configuration shown in Figure 19.

Figure 19: S-VLAN Tunnels for Ethernet Layer 2 Services over MPLS

In this example, traffic from three VLAN subinterfaces must traverse the MPLS network. To accomplish this using standard S-VLANs, you issue the following commands to configure three separate S-VLANs with the same S-VLAN ID value and different VLAN IDs, as follows:

By contrast, using an S-VLAN tunnel achieves the same result, but requires you to issue only a single svlan id command with the keyword any in place of the VLAN ID value. For example, the following command creates a single interface that tunnels traffic from VLANs configured with an S-VLAN ID of 33 and any VLAN ID to the same destination across the MPLS network. In effect, this command tunnels traffic from all three VLANs shown in Figure 19.

Interface Stacking

When you configure Ethernet layer 2 services over MPLS using S-VLAN tunnels, the only interface that you can stack over an S-VLAN tunnel is an MPLS tunnel, which you configure using the MPLS tunneling command (mpls-relay or route interface) that is appropriate for your configuration. Attempting to configure any other interface type—such as IP, MPLS (nontunnel), or PPPoE—over the S-VLAN tunnel causes the router to generate an error and reject the configuration as invalid.

For details about configuring MPLS and layer 2 services over MPLS, see:

•  Chapter Configuring MPLS in JunosE BGP and MPLS Configuration Guide
•  Chapter Configuring Layer 2 Services over MPLS in JunosE BGP and MPLS Configuration Guide

Configuration Example

This section uses the sample network topology shown in Figure 19 to illustrate the steps for configuring S-VLAN tunnels for Ethernet layer 2 services over MPLS.

To configure S-VLAN tunnels for Ethernet layer 2 services over MPLS:

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 to create the VLAN major interface.
   host1(config-if)#encapsulation vlan
3. Create a VLAN subinterface.
   host1(config-if)#interface fastEthernet 8/1.1
4. Create the S-VLAN tunnel. This interface tunnels traffic from VLANs configured with an S-VLAN ID of 33 and any VLAN ID to the same destination across the MPLS network.
   host1(config-if)#svlan id 33 any
5. Assign an S-VLAN Ethertype.
   host1(config-if)#svlan ethertype 8100
6. Create the MPLS tunnel interface using the appropriate MPLS tunneling command for your configuration. For example:
   host1(config-if)#route interface tunnel mpls:tunnel3 45

   For complete instructions on configuring the MPLS tunnel, see chapter Configuring Layer 2 Services over MPLS in JunosE BGP and MPLS Configuration Guide.

7. Repeat Steps 1 through 6 using unique values to configure the S-VLAN tunnel and MPLS tunnel interfaces on the remote E Series router. For example:
   host2(config)#interface fastEthernet 3/1host2(config-if)#encapsulation vlanhost2(config-if)#interface fastEthernet 3/1.1 host2(config-if)#svlan id 83 any host2(config-if)#svlan ethertype 88a8 host2(config-if)#route interface tunnel mpls:tunnel2 45