Administrator Guide

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 rst 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, lls 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
trac. 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 rst row, followed by the RPF router details
along the path in the consequent rows, and nally 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
show ip mroute
View the multicast routing table.
Syntax
show ip mroute [vrf vrf-name] [static | group-address [source-address] | count
| snooping [vlan vlan-id] [group-address [source-address]] | summary | vlt
[group-address [source-address] | count]
Parameters
vrf vrf-name (OPTIONAL) Enter the keyword vrf followed by the name of the VRF to congure this
setting on that VRF.
Multicast 1027