Multihomed Groups Overview
In the Junos Space product, you can create a multihomed group to connect a customer site to multiple PE routers to provide redundant connectivity across a VPLS site, while preventing the formation of Layer 2 loops in the service provider’s network. A VPLS site multihomed to two or more N-PE routers provides redundant connectivity in the event of a PE-router-to-CE-device link failure or the failure of an N-PE router. Figure 1 shows two multihomed sites in which each access switch is connected to a primary and a backup PE router. If the PE router functioning as the primary device fails or the link connection between the access switch and PE router fails, the backup PE router automatically takes over the role of primary device.
This multihomed groups overview includes the following topics:
Prerequisites to Create Multihomed Groups
The following requirements must be met before you create a multihomed group:
Ensure that the N-PE devices included in the multihomed group meet the following requirements:
The same site ID is assigned to the N-PE devices that are connected to the same CE devices.
The same route distinguisher is assigned to the N-PE devices that are connected to the same CE devices.
The N-PE device is either designated as a primary interface or allows the router to select the interface to be used as the primary interface.
If the router selects the interface, the interface that is used to connect the N-PE device to the site depends on the order in which the interfaces are listed in the N-PE device’s configuration. The first operational interface in the set of configured interfaces is selected as the designated interface. If this interface fails, the next interface in the list is selected to send and receive traffic for the site.
Perform device discovery to import the N-PE devices that you want to include in the multihomed group.
Pre-stage the N-PE devices that you want to include in multihomed groups.
Required N-PE Device Configuration
The configuration for each N-PE device that you include in a multihomed group must include the following statements:
Administrator Roles Required to Create Multihomed Groups
The steps required to create a multihomed group are performed by users with different levels of privilege. The Junos Space software provides predefined administrator roles that provide the necessary privilege for each step in the sequence:
The Device Manager role allows an administrator to discover the PE devices that you want to include in the multihomed group.
The Service Manager role allows an administrator to perform device pre-staging actions including discovering and assigning device roles and importing the connectivity file for the multihomed group.
The Service Designer roles allows an administrator to create and publish a service definition.
The Service Activator (less privileged) role allows an administrator to perform provisioning tasks, including creating and managing customers, service orders, and services.
For details about predefined administrator roles, see Predefined Roles Overview in the Junos Space Network Application Platform User Guide.
Creating Multihomed Groups Process Overview
To create a multihomed group to connect a customer site to multiple PE routers:
Create an XML connectivity file to name the multihomed group and configure endpoint connections between the CE device (access switch) and N-PE devices—Each multihomed group connects individual customer sites to up to three PE routers to provide redundant connectivity across a VPLS site. For step-by-step instructions on creating an XML connectivity file for multihomed groups, see Creating a Connectivity File for Multihomed Groups.
Upload the XML connectivity file in Junos Space—After you create the XML connectivity file, you upload it to Junos Space. For step-by-step instructions on uploading an XML connectivity file for multihomed groups, see Uploading a Connectivity File to Create Multihomed Groups.
Create a VPLS service definition with multihoming enabled.
Publish the VPLS service definition.
Create a customer for the service.
Create a VPLS service order based on a VPLS service definition with multihoming enabled.
When you create the service order, you select one or more multihomed groups you want to include in the service from the Select Endpoint PE devices screen.
Deploy the service order.
Perform a functional audit to determine whether the service is up or down.
If the functional audit reports that the service is up, the customer(s) can begin using the service.
You are required to create a multihomed group only if you intend to create redundant VPLS services. For point-to-point LDP services and Layer 2 VPN services, you can enable the redundant feature when you create the service order.