Administrator Guide

Printing Multicast Traceroute (mtrace) Paths
Dell Networking OS supports Multicast traceroute.
MTRACE is an IGMP-based tool that prints the network path that a multicast packet takes from a source to a destination, for a particular
group. Dell Networking OS has mtrace client and mtrace transit functionality.
MTRACE Client — an mtrace client transmits mtrace queries and print the details from received responses.
MTRACE Transit — when a Dell Networking system is an intermediate router between the source and destination in an MTRACE
query, Dell Networking OS computes the RPF neighbor for the source, fills in the request, and forwards the request to the RPF
neighbor. When a Dell Networking system is the last hop to the destination, Dell Networking OS sends a response to the query.
To print the network path, use the following command.
Print the network path that a multicast packet takes from a multicast source to receiver, for a particular group.
EXEC Privilege mode
mtrace multicast-source-address multicast-receiver-address multicast-group-address
From source (?) to destination (?)
----------------------------------------------------------------------------------------
|Hop| OIF IP |Proto| Forwarding Code |Source Network/Mask|
----------------------------------------------------------------------------------------
0 “destination ip(to)” --> Destination
-1 “Outgoing intf addr” “Proto” “Err/fwd code if present” “Src Mask”
-2 “Outgoing intf addr” “Proto” “Err/fwd code if present” “Src Mask”
.
.
-“n” “source ip(from)” --> Source
-----------------------------------------------------------------------------------------
The mtrace command traverses the path of the response data block in the reverse direction of the multicast data traffic. As a result,
the tabular output of the mtrace command displays the destination details in the first row, followed by the RPF router details along the
path in the consequent rows, and finally the source details in the last row. The tabular output contains the following columns:
Hop — a hop number(counted negatively to indicate reverse-path)
OIF IP — outgoing interface address
Proto — multicast routing protocol
Forwarding code — error code as present in the response blocks
Source Network/Mask — source mask
The following is an example of tracing a multicast route.
R1>mtrace 103.103.103.3 1.1.1.1 226.0.0.3
Type Ctrl-C to abort.
Querying reverse path for source 103.103.103.3 to destination 1.1.1.1 via group 226.0.0.3
From source (?) to destination (?)
-----------------------------------------------------------------
|Hop| OIF IP |Proto| Forwarding Code |Source Network/Mask|
-----------------------------------------------------------------
0 1.1.1.1 --> Destination
-1 1.1.1.1 PIM Reached RP/Core 103.103.103.0/24
-2 101.101.101.102 PIM - 103.103.103.0/24
-3 2.2.2.1 PIM - 103.103.103.0/24
-4 103.103.103.3 --> Source
------------------------------------------------------------------
The following table explains the output of the mtrace command:
Table 63. mtrace Command Output — Explained
Command Output Description
Querying reverse path for source
103.103.103.3 to destination 1.1.1.1 via
group 226.0.0.3
mtrace traverses the reverse path from the given destination to the given
source for the given group
582 Multicast Features