MPM-1000A Operator Manual
1000-7075 Rev E
10-6
10.4 PIM Snooping and Multicast
The Modem is able to snoop Protocol Independent Multicast (PIM) version 2 (PIMv2)
packets and automatically establish NCW corresponding multicast groups.
“Snooping” is the process of a protocol layer observing the contents of an upper layer
protocol, and taking action. The Modem is generally a link layer (layer 2) bridge device.
In this case, it snoops PIMv2 packets that flow upper protocols, over UDP in this case.
When the Modem recognizes a new multicast group while snooping PIMv2 packets, it
automatically establishes a corresponding NCW multicast group. An NCW multicast
group allows the Modem, as a layer-2 device, to efficiently transport multicast traffic.
The purpose of PIM Snooping and NCW Multicast is to reduce the incidence of
broadcasting to all modems in an NCW network. Without PIM Snooping, and when PIM
Snooping is disabled, modems broadcast multicast packets to all other modems.
However, with PIM Snooping, modems send multicast packets only to the modems that
are registered (automatically via the PIM Snooping process) to receive the multicast
packets. PIM Snooping can save air bandwidth, transmit power, satellite power, Modem
receive processing and network receive processing (e.g., attached routers).
10.5 Multicast Configurations
The
Multicast Config
window allows you to adjust the current Multicast configuration
settings. These settings include the enabling/disabling of PIM snooping, Orderwire
transmit timing and message limits, the maximum allowable multicast groups and a list
of MAC addresses that cannot establish multicast groups.
Refer to Table 10-4 Multicast Config Tab for data descriptions for this window.
Figure 10-4 Multicast Config Tab
