Multi-Instance Application In Multicast - 3Com MSR 50 Series Configuration Manual

1096 C 67: M
HAPTER ULTICAST
Multi-Instance
Application in Multicast
n
O
VERVIEW
The P device belongs to the public network. The CE devices belong to their
■
respective VPNs. Each CE device serves its own network and maintains only one
set of forwarding mechanism.
The PE devices interface with the public network and the VPN networks,
■
serving multiple networks at the same time. On each PE device, the
information for different networks must be strictly distinguished and a separate
forwarding mechanism must be maintained for each network. On a PE device,
a set of software and hardware that serves the same network forms an
instance. Multiple instances exist on a PE device at the same time, and an
instance resides on different PE devices.
VPN instances are implemented by the PE devices in a VPNs network. A PE device
supports the public instance and multiple VPN instances at the same time, and
runs an independent multicast service in each instance. A PE device has the
following characteristics:
It maintains a set of independent multicast forwarding mechanism for each
■
instance, including various multicast protocols, a list of PIM neighbors and a
multicast routing table per instance. Each instance searches its own forwarding
table or routing table to forward multicast data.
It guarantees the isolation between different VPN instances.
■
It implements information exchange and data conversion between the public
■
instance and VPN instances.
Multi-instance multicast is the basis of multicast over a VPNs network. With
multicast VPN, as shown in
multicast stream to a multicast group, of all possible receivers on the network for
that group, only those belong to VPN A can receive the multicast stream. The
multicast data is multicast both in VPN A and in the public network.
Only one set of unified multicast service runs on a non-PE device. It is called
■
public instance.
The configuration made in VPN instance view only takes effect on the VPN
■
instance interface only. An interface that does not belong to any VPN instance
is called public instance interface.
For more information about multicast VPN, refer to
■
Configuration" on page
Figure 324, when a multicast source in VPN A sends a
1279.
"Multicast VPN