Introduction

This document describes the evolution of multicast over a service provider networks.

Multicast Service Provider

• There are three main ways of running multicast over a service provider:
  • Native IP Multicast - operate one big multicast domain for all customers.
  • GRE Based - utilize GRE tunneling.
  • Label Based - utilize multicast label distribution functionality.

Native IP Multicast

• Operates one multicast domain.
• Multicast groups have to be distinct from each other for each customer. No VPN concept.
• Each P device has to maintain multicast states of all groups. There is no deterministic way of determining the number of states core devices will need to maintain, as that number is related to each customer's multicast usage.
• Not very scalable.
• Not used any more.

GRE Based

• Utilize some form of GRE tunneling for multicast traffic.
• GRE can be between the CE-CE. This is the GRE Overlay method.
• GRE can also be between the PE-PE. This is the mVPN method mainly described in this section.
• Referred to as mVPN or Rosen Draft Multicast as described in RFC6037 - Cisco Systems' Solution for Multicast in BGP/MPLS IP VPNs
• More scalable method with a deterministic way to calculate the number of states core devices had to maintain.
• For more information please see Multicast-mVPN.

Label Based

• Uses either multicast LDP (mLDP) or RSVP-TE to distribute multicast labels.

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