Administrator Guide
mtrace
Trace a multicast route from the source to the receiver.
Syntax
mtrace [vrf vrf-name] {source-address/hostname} [destination-address/hostname]
[group-address/hostname]
Parameters
vrf
vrf-name
Enter the keyword vrf followed by the name of the VRF. If VRF name is not mentioned,
the default VRF will be used. Mtrace is not supported for management VRF.
source-address/
hostname
Enter the source IP address in dotted decimal format (A.B.C.D). This is a unicast address
of the beginning of the path to be traced.
destination-
address/
hostname
Enter the destination (receiver) IP address in dotted decimal format (A.B.C.D). If omitted,
the mtrace starts from the system at which the command is typed.
group-address/
hostnamae
Enter the multicast group address in dotted decimal format (A.B.C.D). If group address is
not given then software shall invokes a weak mtrace. A weak mtrace is one that follows
the RPF path to the source, regardless of whether any router along the path has
multicast routing table state
Command Modes EXEC Privilege
Command History
Version Description
9.11.0.0 Re-introduced the mtrace command on the Dell Networking OS.
7.5.1.0 Expanded to support originator.
7.4.1.0 Expanded to support the intermediate (transit) router.
Usage Information
Mtrace is an IGMP based protocol that provides a multicast trace route facility and is implemented according to
the IETF draft “A trace route facility for IP Multicast” (draft-fenner-traceroute-ipm-01.txt). Dell Networking OS
supports the Mtrace client and transit functionality.
As an Mtrace client, Dell Networking OS transmits Mtrace queries, receives, parses, and prints out the details in
the response packet received.
A transit or intermediate router, forwards mtrace requests to the RPF neighbor after appending its response block
to the packet. In case it is the first hop router, it sends a response.
As an Mtrace transit or intermediate router, Dell Networking OS returns the response to Mtrace queries. After
receiving the Mtrace request, Dell Networking OS computes the RPF neighbor for the source, fills in the request
and the forwards the request to the RPF neighbor.
Example
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 mtrace command traverses the path of the response data block in the reverse direction of the multicast data
traffic. The mtrace command traverses the reverse path to the source from the destination. 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:
1032 Multicast