Determining Which Interfaces Are Downstream And Which; Upstream; Which Upstream - HP ProCurve Secure Router 7203 dl Advanced Management And Configuration Manual

Configuring Multicast Support for a Stub Network
Configuring IGMP Proxy for Multicast Stub Routing Support
N o t e
10-12
For example, to set the helper address for the router in Figure 10-6, you would
enter:
ProCurve(config)# ip mcast-stub helper-address 10.1.1.2
The router must know a route to the helper address.
IGMP
queries
Switch
IGMP report
IGMP report
Group 99
Figure 10-6. Identifying Upstream and Downstream Interfaces and Helper Address
Determining Which Interfaces are Downstream and

Which Upstream

Downstream interfaces connect to the stub networks with multicast hosts.
Generally, these are Ethernet interfaces. Downstream interfaces run IGMP as
a multicast agent and receive IGMP reports from local hosts. Downstream
interfaces also forward multicast messages into networks for which a host
group exists.
The upstream interface is the interface through which the router connects to
remote multicast sources. The upstream interface acts as the IGMP host on
behalf of hosts connected to the downstream interfaces. The router only uses
one upstream interface to forward IGMP joins received on downstream
interfaces towards the multicast source.
Figure 10-6 displays downstream and upstream interfaces on a stub router in
a simplified example network.
IGMP report
IGMP query
Router
Downstream

Upstream

interfaces interface
10.1.1.1
IGMP report
Multicast
Router
Helper
address
10.1.1.2