Configuring An Upstream Interface; Tunneling Multicast Traffic Through The Internet - HP ProCurve Secure Router 7203 dl Advanced Management And Configuration Manual

Configuring an Upstream Interface

An upstream interface is a forwarding helper interface: an interface through
which the router reaches the helper address. The multicast server considers
the upstream interface to be the multicast host. Although you can configure
more than one upstream interface, the router only uses one (the interface that
is the least number of hops from the helper address). Otherwise, the router
would receive multicast source on more than one interface and would not know
how to set the incoming interface for entries in its multicast routing table.
Upstream interfaces on a stub router should fulfill two functions:
Multicast forwarding—The interface receives multicast messages from
the multicast source at a remote site.
IGMP proxy—The interface acts as a multicast host to the multicast server
and forwards IGMP reports, joins, and leaves with its own source address.
The interface also runs an IGMP agent.
To configure an upstream interface (typically, the WAN interface), move to the
logical interface configuration mode context. (You can configure any Layer 2
interface as an upstream interface.)
You enable both IGMP proxy and multicast forwarding functions with the
following command:
ProCurve(config-ppp 1)# ip mcast-stub upstream
You should not enter the ip mcast-stub helper-enable command. Down-
stream interfaces enabled for IGMP proxy will automatically forward IGMP
messages through the upstream interface closest to their helper address.

Tunneling Multicast Traffic through the Internet

In a WAN, multicast packets may travel through networks, such as the Inter-
net, that do not support multicasting. In this case, you must establish a tunnel
through which the router can send the multicasts.
The ProCurve Secure Router supports Generic Routing Encapsulation (GRE)
tunneling. When a packet arrives on one tunnel endpoint, the router
encapsulates it with a new IP header, which includes the IP address of the
remote tunnel endpoint, and a GRE header. The router then forwards the
packet. Routers in the non-multicast network can read the delivery header to
forward the multicast packet to the tunnel endpoint.
Configuring Multicast Support for a Stub Network
Configuring IGMP Proxy for Multicast Stub Routing Support
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