Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?

Example: Basic IPv4 Multicast over a Layer 3 VPN Configuration

 
Figure 1: Basic IPv4 Multicast over a Layer 3 VPN Topology Diagram
Basic IPv4 Multicast over a Layer 3
VPN Topology Diagram

In Figure 1, the multicast source sends to group 229.1.1.1, and the receiver listens to the same group address. The VPN C-RP is located at Router CE1, whereas the SP-RP is located at Router P0. The routing instances are named VPN-A on both routers PE0 and PE1.

Router CE0

In this example, the interface all statement is configured. If the topology requires only a few interfaces to be configured for PIM, then loopback interface lo0 must also be one of the configured interfaces.

Router PE0

Router PE0 also requires a standard VPN configuration, along with the PIM instance configuration. The vpn-group-address command is the only new PIM statement with PIM used exclusively with a routing instance multicast configuration.

Router PE0

Router P0

Again, if the configuration calls for specific interfaces to be configured for PIM, loopback interface lo0 must be included as one of the interfaces running PIM.

Router PE1

Router CE1

Verifying Your Work

To verify correct operation of basic IPv4 multicast over a Layer 3 VPN, use the following commands:

  • show pim

  • show pim rps

  • show pim rps instance instance-name

  • show pim join

  • show pim join extensive

  • show pim join extensive instance instance-name

  • show multicast route extensive

  • show multicast next-hops

  • show interfaces mt-fpc/pic/port extensive

The following sections show the output of these commands used with the configuration example:

RP Information

You can view PIM information for the master instance with the show pim command. You can see information on the PIM routing instance with the show pim (rps | join extensive) instance instance-name command. Output verifying the SP-RP (10.254.71.47) as well as the VPN C-RP (10.254.245.91) follows.

user@PE0> show pim rps

PIM Information Before Multicast Transmission

With the configuration properly set, the backbone PIM sessions should be established before any traffic is forwarded. In the output below, the routers were configured, but the traffic source was not transmitting and the receiver was not requesting to be part of a group. Notice that there is no PIM join information for the routing instances yet.

Router PE0

user@PE0> show pim join extensive

Router P0

user@P0> show pim join extensive

Router PE1

user@PE1> show pim join extensive

Successful PIM Join Verification

In the remaining output for this example, the show pim join output shows group participation. Also displayed is the output from the show multicast route extensive and show multicast next-hop commands. The join output for PIM within a VPN will reference the group 229.1.1.1, while the service provider side of the network will reference the join information for group 239.1.1.1 (which is the VPN group ID). In the show multicast route extensive output, you can view the group, sender, and upstream interface toward the sender.

Router CE0

user@CE0> show pim join
user@CE0> show multicast route extensive
user@CE0> show multicast next-hops

Router PE0

user@PE0> show pim join extensive
user@PE0> show interfaces mt-1/1/0 extensive
user@PE0> show pim join extensive instance VPN-A
user@PE0> show pim join
user@PE0> show multicast route extensive
user@PE0> show multicast route extensive instance VPN-A
user@PE0> show multicast next-hops

Router P0

user@P0> show pim join
user@P0> show multicast route extensive
user@P0> show multicast next-hops

Router PE1

user@PE1> show pim join extensive
user@PE1> show pim join extensive instance VPN-A
user@PE1> show interfaces mt-1/1/0 extensive
user@PE1> show multicast route extensive
user@PE1> show multicast route extensive instance VPN-A
user@PE1> show multicast next-hops

Router CE1

user@CE1> show pim join
user@CE1> show multicast route extensive
user@CE1> show multicast next-hops