Administrator Guide

● MTRACE Transit — when a Dell EMC Networking system is an intermediate router between the source and destination in
an MTRACE query, Dell EMC Networking OS computes the RPF neighbor for the source, fills in the request, and forwards
the request to the RPF neighbor. When a Dell EMC Networking system is the last hop to the destination, Dell EMC
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 71. 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
568 Multicast Features