Multicast VPN introduction

The new way refers to the setting up of Multipoint LSP in the MPLS VPN environment to carry multicast traffic in the VPN. Here, all CE routers belong to a single customer at different branches. There is no multicast receiver behind CE3 router. The MPLS core is PIM-free. Only PE routers will run PIM with the CE routers.

A separate function is required to enable IP multicast over a Multiprotocol Label Switching Virtual Private Networks (MPLS VPNs) network, as MPLS has no native ability to support it.

The Service Provider MVPN network forwards the customer IP multicast data to remote customer sites. To achieve this, customer traffic (C-packets) is encapsulated at the Service Provider PE inside P- packets. The encapsulated P-packet is then forwarded to remote PE sites as native multicast inside the P-Network.

During this process, the P-Network has no knowledge of the C-Network traffic. The PE is the device that participates in both networks. Note there may be more than one Customer Network per PE

PE routers configuration

The Loopback 0 interface of PE1 router is configured to be used as the Root Node IP address. 

The Opaque value for the multipoint LSP is constructed based on the VPN ID value of 1:1. The mdt default mpls mldp command creates the MP2MP LSP known to all PE routers for that particular VRF. This LSP is used to forward all customer multicast traffic by default.

Fig 1.1-Multicast VPN

    Configuration on PE1 Router

The configuration of PE2 and PE3 is same as PE1 router.

   Configuration on PE2 Router

    Configuration on PE3 Router

No multicast traffic is sent by CE routers at this stage.