3Com 3C13636 Configuration Manual page 750

3Com Router 3000 Ethernet Family
Configuration Guide
Three types of multicast routing tables are involved in the multicast implementation of V
2.41: 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 multicast kernel routing table.
II. Tracing the Network Path of Multicast Data
You can use the mtracert command in any view to trace the network path multicast
data take from multicast source to destination receiver and locate the faults.
Table 2-8 Trace the network path of multicast data
Trace the network path multicast data
take
destination receiver
If only multicast source address 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 that case, trace reversely hop by hop from the local router to the first
hop router that connects directly to multicast source, following RPF rule.
If only multicast source address and the last hop address are specified, the group
address defaults to 0.0.0.0. In that case, trace reversely hop by hop from the last
hop router to the first hop router that connects directly to multicast source,
following RPF rule.
If only source address and group address are specified, the last hop address
defaults to that of a physical interface of the local router. In that case, 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 multicast source address, destination address and group address are all
specified, trace reversely from the last hop router to the first hop router which is
directly connected with multicast source following the corresponding entry (S, G)
in the multicast kernel routing table of each router on the path.
The trace mode is called weak trace if the group address is 0.0.0.0.
Operation
from multicast source
3Com Corporation
Chapter 2 Common Multicast Configuration
mtracert
to
[ last-hop-address ] [ group-address ]
2-5
Command
source-address