Introduction To Md-Vpn - 3Com MSR 50 Series Configuration Manual

1282 C 75: M
HAPTER ULTICAST

Introduction to MD-VPN

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VPN C
ONFIGURATION
For details about the concepts of Protocol Independent Multicast (PIM), bootstrap
router (BSR), candidate-BSR (C-BSR), rendezvous point (RP), candidate RP (C-RP),
shortest path tree (SPT) and rendezvous point tree (RPT), refer to
Configuration" on page
Router implements multicast VPN by means of the multicast domain (MD)
method. This multicast VPN implementation is referred to as MD-VPN.
The most significant advantage of MD-VPN lies in that it requires only the PE
devices to support multiple instances. Multicast VPN can be implemented without
upgrading any CE devices and P devices, and without changing the original PIM
configuration of the CE devices and the P device. In other words, the MD-VPN
solution is transparent to the CE devices and the P device.
Basic concepts in MD-VPN
The basic concepts involved in MD-VPN are described in
Table 49 Basic concepts in MD-VPN
Concept
Multicast VPN routing
and forwarding (MVRF)
Multicast domain (MD)
Multicast tunnel (MT)
Multicast tunnel
interface (MTI)
Share-group
1161.
Description
Each VPN instance maintains its unicast routing and forwarding
table, which is referred to as VPN routing and forwarding table
(VRF). With Layer 3 multicast enabled, a VPN instance also maintains
its multicast routing and forwarding table. The unicast routing and
forwarding table and the multicast router and forwarding table
simultaneously maintained by a VPN instance are referred to as an
MVRF in general. Each MVRF can belong to only one MD. Different
MVRFs join the same MD and are interconnected by means of the
multicast tunnel (MT) automatically established in the MD to enable
multicast service between different sites and form a multicast VPN
network.
A set of interconnected MVRFs that can send multicast traffic to
each other. Each MD corresponds to a multicast-capable VPN, and
all the PE devices interfacing with this VPN belong to this MD.
Different VPNs corresponds to different MDs, but one PE can belong
to multiple MDs at the same time.
The tunnel that interconnect all MVRFs in the MD for delivering
private network traffic within the MD. In the perspective of an
MVRF, the MT is like a multi-access LAN. Each MVRF access this
multi-access LAN through an MTI.
In perspective of a VPN instance on a PE device, an MT is a virtual
interface, which is referred to as an MTI. Upon share-group and MTI
binding configuration for a VPN instance, an MTI is automatically
created per MVRF. It is the entrance to or exit of an MT, or
equivalent to an entrance to or exit of an MD. An MVRF uses an MTI
to access the MD. In the perspective of an MVRF, an MTI is like a
LAN interface, while the MD is like a LAN network, to which all the
PE devices are attached. An MTI handles only multicast packets, but
not unicast packets.
In the public network, each MD is assigned an independent
multicast address, which is called share-group. A share-group is the
unique identifier of an MD in the public network. It is used to build a
share-MDT corresponding to the MD on the public network. Each
MD has a unique share-group.
"PIM
Table 49.