Quick Reference Guide

PowerConnect B-Series TI24X Configuration Guide 525
53-1002269-02
Tracing a multicast route
19
Tracing a multicast route
The Dell implementation of Mtrace is based on “A ‘traceroute’ facility for IP Multicast”, an Internet
draft by S. Casner and B. Fenner. To trace a PIM route, use the following CLI method..
To trace a PIM route to PIM source 209.157.24.62 in group 239.255.162.1, enter a command such
as the following.
PowerConnect#mtrace source 209.157.24.62 group 239.255.162.1
Type Control-c to abort
Tracing the route for tree 209.157.23.188
0 207.95.7.2
0 207.95.7.2 Thresh 0
1 207.95.7.1 Thresh 0
2 207.95.8.1 Thresh 0
3 207.157.24.62
Syntax: mtrace source <ip-addr> group <multicast-group>
The source <ip-addr> parameter specifies the address of the route source.
NOTE
In IP multicasting, a route is handled in terms of its source, rather than its destination. When you
trace an IP route, you specify its destination, but when you trace a PIM route, you specify its source.
The group <multicast-group> parameter specifies the PIM group the source IP address is in.
Figure 92 shows an example of an IP multicast group. The command example shown above is
entered on PIM router A.
FIGURE 92 Example of a PIM group
The command example above indicates that the source address 209.157.24.62 is three hops
(three PIM switches) away from PIM Switch A. In PIM terms, each of the three switches has a
forwarding state for the specified source address and multicast group. The value following
“Thresh” in some of the lines indicates the TTL threshold. The threshold 0 means that all multicast
packets are forwarded on the interface. If an administrator has set the TTL threshold to a higher
value, only packets whose TTL is higher than the threshold are forwarded on the interface. The
threshold is listed only for the PIM switch hops between the source and destination.
e 4
207.95.7.1
e 5
207.95.8.10
e 8
207.95.8.1
e 3
207.95.7.2
e 11
8.8.8.164
Multicast group
239.255.162.1
e 19
209.157.24.62
Multicast group
239.255.162.1
PIM Switch B
PIM Switch C
PIM Switch A
Client
Server