Configuring Any-Source Multicast for Draft-Rosen VPNs
If the service provider supports PIM, you can configure multicast for a Layer 3 virtual private network (VPN) using PIM version 2 as the multicast protocol. The Junos OS complies with RFC 4364 and Internet draft draft-rosen-vpn-mcast-07.txt, BGP/MPLS VPNs (known as draft-rosen) and Multicast in MPLS/BGP VPNs.
This section describes configuration of an any-source multicast VPN (MVPN) using dual PIM configuration with a customer RP and provider RP and mapping the multicast routes from customer to provider (known as draft-rosen). You can also configure a MVPN using multiprotocol BGP (MBGP), or next-generation MVPN, which is described in the next section. In this section, the term Layer 3 VPNs is used to refer to draft-rosen MVPNs.
For multicast to work on draft-rosen Layer 3 VPNs, each of the following routers must have a Tunnel Services PIC, which is hardware used to encapsulate and de-encapsulate data packets into tunnels:
- Each provider edge (PE) router
- Any provider (P) router acting as the RP
- Any customer edge (CE) router that is acting as a source's DR or as an RP. A receiver's designated router does not need a Tunnel Services PIC.
The following sections describe how to configure multicast for Layer 3 VPNs:
Configuring the VPN
You must first configure the VPN. Figure 1 shows a configuration for VPN-A, used as an example later in this section. For more information about configuring VPNs, see the Junos VPNs Configuration Guide.
Figure 1: Configuring the VPN
Configuring PIM Connectivity Between the Provider and PE Routers
To configure PIM on the main routing instance for all provider and PE routers, include statements at the [edit protocols pim] hierarchy level:
- Configure the interfaces between each provider router and the PE routers by including the interface statement at the [edit protocols pim] hierarchy level. On all PE routers, enable PIM version 2 and sparse mode on interface lo0 of the PE routers, either by configuring that specific interface or by including the statement set version 2 mode sparse for interface all at the [edit protocols pim] hierarchy level on a PE router.
- Configure PIM version 2 by including the version statement at the [edit protocols pim interface interface-name] hierarchy level.
- Configure sparse mode (the mode in which the PIM interfaces operate) by including the mode statement at the [edit protocols pim interface interface-name] hierarchy level.
- Configure the RP address by including the static statement at the [edit protocols pim rp] hierarchy level. In Figure 2, the provider router is the RP.
Figure 2 shows a multicast configuration on the provider network.
Figure 2: Multicast Configuration on the Provider Network
 | Note: It is possible for the PE router to be configured as the VPN customer RP (C-RP) router. The PE router can also act as the DR. This type of PE configuration can simplify configuration of customer DRs and VPN C-RPs for multicast VPNs. However, the BSR and auto-RP features are not supported. This section does not discuss the use of the PE as the VPN C-RP. |
Configuring Multicast Connectivity on the CE Routers
To configure PIM for the master routing instance on all CE routers, include statements at the [edit protocols pim] hierarchy level:
- Configure the interfaces going toward the provider router acting as the RP by including the interface statement at the [edit protocols pim] hierarchy level. In Figure 3, the interfaces are labeled A and B.
- Configure PIM version 2 by including the version statement at the [edit protocols pim interface interface-name] hierarchy level.
- Configure sparse mode or sparse-dense mode (the mode in which the PIM interfaces operate) by including the mode statement at the [edit protocols pim interface interface-name] hierarchy level.
- Configure the RP address by including the static statement at the [edit protocols pim rp] hierarchy level. In Figure 3, CE2 is the RP router; however, the RP router can be anywhere in the customer network.
Figure 3 shows multicast connectivity on the customer edge.
Figure 3: Multicast Connectivity on the CE Routers
Configuring Multicast Connectivity for the VPN on the PE Router
To configure multicast connectivity for the VPN on the PE router, you must configure a VPN group address and configure the interfaces toward the router acting as the RP. To configure the VPN group address, include the vpn-group-address statement at the [edit routing-instances instance-name protocols pim] hierarchy level:
The PIM configuration in the VPN routing and forwarding (VRF) instance on the PE routers needs to match the master PIM instance on the CE router. Therefore, the PE router contains both a master PIM instance (to communicate with the provider core) and the VRF instance (to communicate with the CE routers). See the Junos VPNs Configuration Guide for information about configuring VPNs on PE routers.
| Note: VRF instances that are part of the same VPN share the same VPN group address. For example, all PE routers containing multicast-enabled routing instance VPN-A share the same VPN group address configuration. In Figure 4, the shared VPN group address configuration is 239.1.1.1. |
Figure 4: Multicast Connectivity for the VPN
Configuring the Routing Group
Routing groups are usually configured at the [edit routing-instances instance-name routing-options] hierarchy level. However, with multicast in VRF instances, you must configure routing groups differently. Configure the multicast routing group by adding the rib-groups statement at the [edit routing-options] hierarchy level.
After you configure the multicast routing group in the main routing instance, add the routing group to the VPN's VRF instance. To do this, include the rib-group statement at the [edit routing-instances instance-name protocols pim] hierarchy level.
For a multicast for Layer 3 VPN example, see Example: Configuring PIM Sparse Mode over Layer 3 VPNs.
