Introduction

This page describes the mVPN architecture.

Multicast Domain Overview

• mVRF - Multicast VRFs.
• GRE Tunnels - Point to multipoint GRE tunnels created from PE to PEs. Destination is a multicast group.
• MDTs - Multicast Distribution Trees.
  • Default MDT
  • Data MDT
• PIM Adj - PIM adj is between CE-PE and PE-PE.
• MTI Interface - Multicast Tunnel Interface, which represents the GRE tunnel.
• RFP Check - Reverse Forwarding Path check used by multicast forwarding to prevent loops.
• mVPN Forwarding
  • C-PIM - multicast forwarding for multicast packets from CE to PE.
  • P-PIM - multicast forwarding for multicast packets from PE to P.

mVRF

• Used to maintain all of the customer multicast states.
• PEs maps all customer groups into one multicast group for each mVRF called Default-MDT.
• Each mVRF belongs to a Default-MDT (Under vrf definition mdt default 239.x.x.x).
• Multicast feature and protocols mVRF aware include:
  • PIM
  • IGMP
  • MSDP

GRE Tunnels (MTI)

• Source of the tunnels it the BGP source address.
• Destination of the tunnel is the customer specific multicast address.

MDT (Default and Data)

• Multicast tunnels used on the MPLS Core.
• Default MDT -
• Data MDT -

PIM Adj

• There is a number of PIM adj within the mVPN network.
• First one is between CE and PE.
• Another one is using the MTI interface with other PEs that have are part of the same mVPN domain.
• The same PIM instance is used for each mVPN domain between the CE-PE and PE-PE based on associated mVPNs. For example CE-PE of mVPN1 will use the same instance for PE1 and PE2 that have mVPN1 configured.

RFP Check

mVPN Forwarding (C and P-PIM)

• Requires the command ip multicast-forwarding vrf X.

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