Ip mcast-stub helper-address Page 556
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Command Reference Guide
Ethernet Interface Configuration Command Set
61200990L1-35E
Copyright © 2005 ADTRAN
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ip mcast-stub helper-address
Use the ip mcast-stub helper-address command to specify an IP address toward which IGMP host reports
and leave messages are forwarded. This command is used in IP multicast stub applications in conjunction
with the ip mcast-stub downstream and ip mcast-stub upstream commands. Use the no form of this
command to return to default.
Syntax Description
Specifies the address to which the IGMP host reports and leave messages are
forwarded.
Default Values
By default, no helper-address is configured.
Applicable Platforms
This command applies to the NetVanta 300, 3000, 4000, and 5000 and Total Access 900 Series units.
Command History
Release 7.1
Command was introduced.
Functional Notes
The helper address is configured globally and applies to all multicast-stub downstream interfaces. The
address specified may be the next upstream hop or any upstream address on the distribution tree for the
multicast source, up to and including the multicast source. The router selects, from the list of
multicast-stub upstream interfaces, the interface on the shortest path to the specified address. The router
then proxies, on the selected upstream interface (using an IGMP host function), any host joins/leaves
received on the downstream interface(s). The router retransmits these reports with addresses set as if the
report originated from the selected upstream interface.
For example, if the router receives multiple joins for a group, it will not send any extra joins out the
upstream interface. Also, if it receives a leave, it will not send a leave until it is certain that there are no
more subscribers on any downstream interface.
Usage Examples
The following example specifies 172.45.6.99 as the helper address:
(config)#ip mcast-stub helper-address 172.45.6.99