Command Reference Guide

Command Reference Guide Tunnel Configuration Command Set

ip mcast-stub upstream

Use the ip mcast-stub upstream command to enable multicast forwarding on an interface and place it in

multicast stub upstream mode. Use the no form of this command to disable.

Syntax Description

No subcommands.

Default Values

By default, this command is disabled.

Command Modes

(config-interface)# Interface Configuration Mode

Valid interfaces include: Ethernet (eth 0/1), PPP virtual interfaces (ppp 1), HDLC

virtual interfaces (hdlc 1), Frame Relay virtual sub-interfaces (fr 1.20), tunnel

interfaces (tunnel 1), and VLAN interface (vlan 1).

Functional Notes

This command is used in IP multicast stub applications in conjunction with the ip mcast-stub

helper-address and ip mcast-stub downstream commands. When enabled, the interface becomes a

candidate to be a helper forwarding interface. If chosen as the best path toward the helper address by the

router's unicast route table, the IGMP host function is dynamically enabled and the interface becomes the

active upstream interface, enabling the router to perform as an IGMP proxy. Though multiple interfaces

may be candidates, no more than one interface will actively serve as the helper forwarding interface. Refer

ip mcast-stub helper-address <ip address> on page 290 and ip mcast-stub downstream on page 791 for

more information.

Usage Examples

The following example enables multicast forwarding on the interface:

(config)#interface tunnel 1

(config-tunnel 1)#ip mcast-stub upstream