# Configuring Transactional Multicast for IGMP

By using ANCP, IGMP is no longer terminated or proxied at the access node. Instead, IGMP passes through the access node transparently. B-RAS terminates both the data PVC and IGMP. After any user permission verification, B-RAS may instruct the access node (using GSMP) to establish a multicast branch for the subscriber port.

ANCP works with a special IGMP session to collect OIF mapping events in a scalable manner. For additional information about configuring IGMP and about OIF mapping, see Configuring IGMP in JunosE Multicast Routing Configuration Guide.

## Creating an IGMP Session for ANCP

Use the l2c ip oif command to create an IGMP session for ANCP. This session enables ANCP to listen to OIF mappings and, in turn, convey cross connect events to the appropriate ANCP neighbor (access node).

l2c ip oif

- Use to create an IGMP session at the virtual router within the context.
- Example
  host1(config)#l2c ip oif
- Use the no version to remove the IGMP session.
- See l2c ip oif.

## ANCP IGMP Configuration Example

In the following example (Figure 18), two subscribers access individual multicast channels through cross connections (branches) that occur on the access node.

Figure 18: Using ANCP with an Access Node

To configure the example, use the following general procedures:

| Note: This example provides general information for configuring ANCP mapping. For detailed information about creating OIF maps, see Configuring Transactional Multicast for IGMP.

1. Configure an OIF map for the access node that maps each multicast group to an outgoing interface.
2. Define ANCP parameters.
3. Enable ANCP to listen to OIF mapping events from IGMP in this virtual router.
4. Create a listening TCP socket in the virtual router (TCP port 6068).
5. Define ANCP neighbor parameters.

   | Note: The ID is a 48 bit quantity that identifies the ANCP neighbor.

6. Configure the ANCP multicast labels (input labels) on the corresponding outgoing interfaces.
7. Configure the ANCP output labels, the neighbor information on the subscriber interfaces, and apply the OIF map.

   When Subscriber A requests to join 232.1.1.1, ANCP transmits an add branch message with the corresponding input and output labels that cross-connect
   port 3 and port 6 on Access Node 1.

## Complete Configuration Example

The following example contains the commands used to configure ANCP. You can customize and use this example in your own network.

You can copy the text into a text editor and modify it (removing all prompts and changing values) for immediate use or save the modified example as a script (.scr) file. Script files allow you to execute commands as though they were entered at the terminal. For information about creating and executing script files, see Command Line Interface in JunosE System Basics Configuration Guide.

!Configure an OIF map host1(config)#ip igmp oif-map OIFMAP atm 2/0.101 232.1.1.1 10.1.1.1 host1(config)#ip igmp oif-map OIFMAP atm 2/0.102 232.1.1.2 10.1.1.2 !Define ANCP parameters host1(config)#l2c host1(config-l2c)#session-timeout 15 !Enable ANCP to listen to OIF mapping events from IGMP in this virtual router host1(config)#l2c ip oif !Create a listening TCP socket in the virtual router host1(config)#l2c ip listen !Define ANCP neighbor parameters.host1(config-l2c)#neighbor ACCESS_NODE_1 host1(config-l2c-neighbor)#id 09af.15bc.3156 !Configure ANCP multicast labels on the corresponding outgoing interfaces host1(config)#interface atm 2/0.101 host1(config-interface)#ip igmp version passive host1(config-interface)#l2c peer-attachment-id “ in_multicast_port_3” host1(config)#interface atm 2/0.102 host1(config-interface)#ip igmp version passive host1(config-interface)#l2c peer-attachment-id “ in_multicast_port_5” !Configure ANCP output labels, neighbor information, and apply OIF map host1(config)#interface atm 2/0.11 host1(config-interface)#ip igmp apply-oif-map OIFMAP host1(config-interface)#l2c end-user-id “ out_subscriber_port_6” neighbor ACCESS_NODE_1 host1(config)#interface atm 2/0.12 host1(config-interface)#ip igmp apply-oif-map OIFMAP host1(config-interface)#l2c end-user-id “ out_subscriber_port_7” neighbor ACCESS_NODE_1