Command Reference Guide

3Com Router 3000 Ethernet Family
Command Reference Guide
Chapter 1 Multicast Common Configuration
Commands
3Com Corporation
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Parameter
group-address: Multicast group address, used to specify a multicast group and display
the corresponding routing table information of the group. The value ranges from
224.0.0.0 to 239.255.255.255.
source-address: Unicast IP address of the multicast source.
mask: Mask.
mask-length: Length of mask. Because “1” in 32-bit mask is required to be continuous,
the mask in dotted decimal notation format can be replaced by mask-length
(mask-length is the number of continuous “1”s in the mask).
incoming-interface: Incoming interface of the multicast route entry.
register: Register interface of PIM-SM.
Description
Use the display multicast routing-table command to view the information of IP
multicast routing table.
This command displays the multicast routing table information, while the display
multicast forwarding-table command displays the multicast forwarding table
information.
The entry (S, G) in the multicast routing table, i.e., (multicast source, multicast group)
acts as the independent entry in the table. Each entry has a unique Upstream,
indicating the interface through which RPF goes to the multicast source. Each entry
has also a Downstream List, indicating which interfaces need multicast forwarding. The
related information about (S, G) includes:
z proto: the multicast protocol number which possesses the (S, G) (in hexadecimal
notation format).
z Flags: all kinds of flags, such as RPT 0x1, WC 0x2, SPT 0x4, NEG CACHE 0x8
and JOIN SUPP 0x10. All the flags are marked by binary “bit”. In which, RPT
indicates the (S, G) is in the shared tree status. WC is the abbreviation of wildcard.
SPT indicates the shortest path tree. NEG CACHE indicates the cache record that
the downstream interface list is null. JOIN SUPP indicates the prune suppression
status.
Example
# Display the corresponding route entry information of multicast group in the multicast
routing table.
<3Com> display multicast routing-table
Multicast Routing Table