3Com SuperStack 4 Configuration Manual page 167

Table 187 Displaying and debugging Common Multicast Configuration
Operation
Enable multicast forwarding
status debugging
Disable multicast forwarding
status debugging
Enable multicast kernel
routing debugging
Disable multicast kernel
routing debugging
There are three types of multicast routing tables: individual multicast routing tables
of each multicast routing protocol; a multicast kernel routing table integrating the
routing information of those individual routing tables; and a multicast forwarding
table in conformity with the kernel routing table and in charge of the multicast
packet forwarding.
Multicast forwarding table is mainly used in debugging. Generally, users can
obtain required information by viewing the multicast kernel routing table.
Tracing the Network Path of Multicast Data
You can use the
mtracert
multicast data taken from multicast source to destination receiver any locate any
faults.
Table 188 Tracing the Network Path of Multicast Data
Operation
Trace the network path multicast
data taken from multicast source to
destination receiver
If the multicast source address only is specified, the last hop address defaults to
■
the address of a physical interface of the local router and the group address
defaults to 0.0.0.0. In this instance, trace reversely hop by hop from the local
router to the first hop router that connects directly to multicast source,
following RPF rule.
If the multicast source address and the last hop address are specified, the group
■
address defaults to 0.0.0.0. In this instance, trace reversely hop by hop from
the local router to the first hop router that connects directly to multicast
source, following RPF rule.
If the source address and group address only are specified, the last hop address
■
defaults to that of a physical interface of the local router. In this instance, trace
reversely from the local router to the first hop router which is directly
connected with multicast source, following the associated entry (S, G) in the
multicast kernel routing table of each router on the path.
If the multicast source address, destination address and group address are all
■
specified, trace reversely from the last hop router to the first hop router which
directly connected with multicast source following the corresponding entry (S,
G) in the multicast kernel routing table or each router on the path.
The trace mode is called weak trace if the group address is 0.0.0.0.
Common Multicast Configuration
Command
debugging multicast status-forwarding
undo debugging multicast status-forwarding
debugging multicast kernel-routing
undo debugging multicast kernel-routing
command in any view to trace the network path
Command
mtracert { source-address } [
last-hop-address ] [ group-address ]
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