This section describes an alternative way to configure MVPNs. Instead of using dual PIM configuration with a customer RP and provider RP and “mapping” the multicast routes from customer to provider (the Draft-Rosen approach), customer multicast routing information can be sent around the provider's VPN using multiprotocol BGP (MBGP) (next generation MVPNs).
You can now configure PIM auto-RP, bootstrap router (BSR) RP, PIM dense mode, and mtrace for next generation multicast VPN networks. Auto-RP uses PIM dense mode to propagate control messages and establish RP mapping. You can configure an auto-RP node in one of three different modes: discovery mode, announce mode, and mapping mode. BSR is the IETF standard for RP establishment. A selected router in a network acts as a BSR, which selects a unique RP for different group ranges. BSR messages are flooded using the data tunnel between PE routers. When you enable PIM dense mode, data packets are forwarded to all interfaces except the incoming interface. Unlike PIM sparse mode, where explicit joins are required for data packets to be transmitted downstream, data packets are flooded to all routers in the routing instance in PIM dense mode. For a complete configuration example of a Layer 3 VPN using MBGP, see the MVPN chapter of the JUNOS Feature Guide.
This section shows you how to configure a MVPN using MBGP. If you have multicast VPNs based on Draft-Rosen, they will continue to work as before and are not affected by the configuration of MVPNs using MBGP.
The network configuration used for most of the examples in this section is shown in Figure 37.
Figure 37: Example Network for MVPN Configuration Using MBGP
In the figure, two VPNs, VPN A and VPN B, are serviced by the same provider at several sites, two of which have CE routers for both VPN A and VPN B (site 2 is not shown). The PE routers are shown with VRF tables for the VPN CEs for which they have routing information. It is important to note that no multicast protocols are required between the PE routers on the network. The multicast routing information is carried by MBGP between the PE routers. There may be one or more BGP route reflectors in the network. Both VPNs operate independently and are configured separately.
Both the PE and CE routers run PIM sparse mode and maintain forwarding state information about customer source (C-S) and customer group (C-G) multicast components. CE routers still send a customer's PIM join messages (PIM C-Join) from CE to PE, and from PE to CE, as shown in the figure. But on the provider's backbone network, all multicast information is carried by MBGP. The only addition over and above the unicast VPN configuration normally used is the use of a special provider tunnel (provider-tunnel) for carrying PIM sparse mode message content between provider nodes on the network.
There are several scenarios for MVPN configuration using MBGP, depending on whether a customer site has senders (sources) of multicast traffic, has receivers of multicast traffic, or a mixture of senders and receivers. MVPNs can be:
Each type of MVPN differs more in the configuration VPN statements than the provider tunnel configuration. For information about configuring VPNs, see the JUNOS VPNs Configuration Guide.
This section describes the configuration of each major type of multicast VPN:
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