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Multicast Routing
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Displaying the Multicast Routing Table
You can display information on each multicast route this router has learned via
DVMRP or PIM. The router learns multicast routes from neighboring routers, and
also advertises these routes to its neighbors. The router stores entries for all paths
learned by itself or from other routers, without considering actual group membership
or prune messages. The routing table therefore does not indicate that the router has
processed multicast traffic from any particular source listed in the table. It uses these
routes to forward multicast traffic only if group members appear on directly-attached
subnetworks or on subnetworks attached to downstream routers.
Field Attributes
• Group Address – IP group address for a multicast service.
• Source Address – Subnetwork containing the IP multicast source.
• Netmask – Network mask for the IP multicast source.
• Interface – Interface leading to the upstream neighbor.
• Owner – The associated multicast protocol (i.e., DVMRP or PIM).
• Flags – The flags associated with each interface indicate prune (P) if the
downstream interface has been recently terminated or forwarding (F) if the
interface is still active.
• Detail – This button displays detailed information for the selected entry.
• Upstream Router
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– The multicast router immediately upstream for this group.
• Downstream
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– Interface(s) on which multicast subscribers have been recorded.
26. These items are displayed in the IP Multicast Routing Entry (Detail) table.