Configuring the Remote Site ID

The remote site ID allows you to configure a sparse Layer 2 VPN topology. A sparse topology means that each site does not have to connect to all the other sites in the VPN; thus it is unnecessary to allocate circuits for all the remote sites. Remote site IDs are particularly important if you configure a topology more complicated than full-mesh, such as a hub-and-spoke topology.

The remote site ID (configured with the remote-site-id statement) corresponds to the site ID (configured with the site-identifier statement) configured at a separate site. Figure 6 illustrates the relationship between the site identifier and the remote site ID.

Figure 6: Relationship Between the Site Identifier and the Remote Site ID

As illustrated by the figure, the configuration for Router PE1 connected to Router CE1 is as follows:

site-identifier 1;

interface so-0/0/0 {

    remote-site-id 2;

}

The configuration for Router PE2 connected to Router CE2 is as follows:

site-identifier 2; 

interface so-0/0/1 {

    remote-site-id 1;

}

The remote site ID (2) on Router PE1 corresponds to the site identifier (2) on Router PE2. On Router PE2, the remote site ID (1) corresponds to the site identifier (1) on Router PE1.

To configure the remote site ID, include the remote-site-id statement:

remote-site-id remote-site-ID;

You can include the remote-site-id statement at the following hierarchy levels:

• [edit routing-instances routing-instance-name protocols l2vpn site site-name interface interface-name]
• [edit logical-routers logical-router-name routing-instances routing-instance-name protocols l2vpn site site-name interface interface-name]

If you do not explicitly include the remote-site-id statement for the interface configured at the [edit routing-instances routing-instance-name protocols l2vpn site site-name] hierarchy level, a remote site ID is assigned to that interface.

The remote site ID for an interface is automatically set to 1 higher than the remote site ID for the previous interface. The order of the interfaces is based on their site-identifier statements. For example, if the first interface in the list does not have a remote site ID, its ID is set to 1. The second interface in the list has its remote site ID set to 2, and the third has its remote site ID set to 3. The remote site IDs of any interfaces that follow are incremented in the same manner if you do not explicitly configure them.