mVPN / Multicast over MPLS / Rosen Draft

Basic Concept of MVPN

• The Service Provider has an IP Network with its own unique IP multicast domain (ie: P-Network).
• The MVPN customer has an IP Network with its own unique IP multicast domain (ie: C-Network).
• 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.

NOTE
The use of GRE in a multicast domain is not the same as the overlay solution in which point-to-point GRE tunnels are used between CE routers. The GRE tunnels used here are between PE routers in a multicast configuration. The tunnels can be considered point-to-multipoint connections if PIM SM is deployed or even multipoint-to-multipoint if using PIM Bi-Dir.
Therefore, the use of GRE for multicast domains is inherently more efficient than GRE overlay.
PIM SM or SSM are the only multicast modes supported in the P-network for mVPN.

 

MDT

• Default Tree
– is used for customer Control Plane and low rate Data Plane traffic
– created by default, all PEs that run multicast VRF are part of the tree
– can use SM and SSM, SSM is preferred because without RP, it is simplier to deploy and maintain
• Data MDT
– created dynamically when there is active multicast source and listeners
– only PEs with active source or listen will join the tree
– Customer traffic initially run on the default tree, when the traffic crossed over the configured threshold, a data MDT is built.

Source ccdewiki
Multicast VPN Design Guide

 

Operation of Multicast MPLS VPN

1. Default MDT is enabled per customer VRF on every PE router that will forward
   multicast packets between customer sites. The VRF on the PE routers thus enabled
   for multicast forwarding is also called the multicast VRF (mVRF).
2.  Default MDT enables multicast forwarding for all PEs where the VRF resides.
3. Control and data packets are transported per VRF over default MDT. Therefore, all
   low bandwidth data that is transported over the default MDT will be delivered to PEs
   where the VRFs reside. Hence, the default MDT is always present.
4. A Data MDT for higher bandwidth sources can be created on the PE routers per VRF, and only routers that are part of the multicast tree for the high bandwidth source receive the multicast packets generated by the high bandwidth source.The data MDT is created on demand for mVPN (S, G) higher bandwidth traffic.
   MDT group addresses are defined by the provider and are unrelated to the groups used by the customer.
   Access to the MDT is via a multicast tunnel interface on PE routers where the PE router always functions as the root of the MDT if it is connected to the CE router containing the multicast source.

 

Configuration sample for Multicast MPLS VPN

• MPLS VPN-CE Router Configuration
– Enable Multicast Routing Globally
– Enable PIM on All Interfaces

• MPLS VPN-CE Multi-VRF Router Configuration
– Enable Multicast Routing Globally
– Enable PIM on VRF All Interfaces

• MPLS VPN- PE Router Configuration
– Enable Multicast Routing Globally or Per VRF
– Configure the Default MDT and Data MDT for the VRF under VRF Definition
– Enable PIM on All VRF and Core Facing Interfaces
– Enable SSM Glogally

• MPLS VPN-P Router Configuration
– Enable Multicast Routing Globally
– Enable PIM on All Interfaces
– Enable SSM Glogally

 

Multicast IPv6 Tunnelling Supports

The following protocols supports IPv6 multicast:
– IPv6inIPv4
– Dual-Stack

The following protocols do not support IPv6 multicast:
– ISATAP
– 6to4
– 6PE
– 6VPE

Source ccdewiki

 

IPv6 Multicast Deployment Models

• There are two models:
– Any Source Multicast (ASM)
– Source Specific Multicast (SSM)

• What is ASM?
– It requires RP
– It uses SPT between Source and RP, and ST between listeners and RP on the initial connection setup but could switch to SPT if the SPT is a more efficient path.
– The PIM model to use is PIM-SM
• What is SSM?
– It does NOT use RP
– It uses SPT (S,G) between listeners and Sources
– The PIM model is PIM-SSM

• When to use ASM?
– When you have distributed Sources, like an enterprise network with multiple DCs and multicast sources in all these DCs
• When to use SSM?
– When you have few sources, like a SP network with a centralized content streaming servers
– When you have more than one PIM domains, because there is no mechanism to exchange RP information between domains for IPv6
– When you do not want to manage RP

Source ccdewiki