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Configuring Multicast for Layer 3 VPNs Using Dual PIM (Draft-Rosen)

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 software complies with RFC 2547 and Internet draft draft-rosen-vpn-mcast-07.txt, BGP/MPLS VPNs (known as Draft-Rosen) and Multicast in MPLS/BGP VPNs, Section 2 (Multicast Domains).

This section describes configuration of an 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.

When you complete the configuration, two multicast tunnel interfaces are configured automatically. You do not need to configure the tunnel interfaces. The interface mt-[xxxxx], used for encapsulation, is in the range from 32,768 through 49,151. The interface mt-[yyyyy], used for de-encapsulation, is in the range from 49,152 through 65,535. For each VPN, the PE routers build a multicast distribution tree within the service provider core network. After the tree is created, each PE router encapsulates all multicast traffic (data and control messages) from the attached VPN and sends the encapsulated traffic to the VPN group address. Because all the PE routers are members of the outgoing interface list in the multicast distribution tree for the VPN group address, they all receive the encapsulated traffic. When the PE routers receive the encapsulated traffic, they de-encapsulate the messages and send the data and control messages to the CE routers.

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.

The following sections describe how to configure multicast for Layer 3 VPNs:

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