Technical Documentation

mtrace

Syntax

mtrace source<routing-instance routing-instance-name>

Release Information

Command introduced before Junos OS Release 7.4.

Command introduced in Junos OS Release 9.0 for EX Series switches.

Description

Display trace information about an IP multicast path.

Options

source: Source hostname or address.
routing-instance routing-instance-name: (Optional) Trace a particular routing instance.

Additional Information

The mtrace command for multicast traffic is similar to the traceroute command used for unicast traffic. Unlike traceroute, mtrace traces traffic backwards, from the receiver to the source.

Required Privilege Level

view

List of Sample Output

mtrace source

Output Fields

Table 1 describes the output fields for the mtrace command. Output fields are listed in the approximate order in which they appear.

Table 1: mtrace Output Fields

Field Name	Field Description
Mtrace from	IP address of the receiver.
to	IP address of the source.
via group	IP address of the multicast group (if any).
Querying full reverse path	Indicates the full reverse path query has begun.
number-of-hops	Number of hops from the source to the named router or switch.
router-name	Name of the router or switch for this hop.
address	Address of the router or switch for this hop.
protocol	Protocol used (for example, PIM).
Round trip time	Average round-trip time, in milliseconds (ms).
total ttl of	Time-to-live (TTL) threshold.

Sample Output

mtrace source

user@host> mtrace 192.1.4.2

Mtrace from 192.1.4.2 to 192.1.1.2 via group 0.0.0.0
Querying full reverse path... * * 
  0  routerA.lab.mycompany.net (192.1.1.2)
 -1  routerB.lab.mycompany.net (192.1.2.2)  PIM  thresh^ 1  
 -2  routerC.lab.mycompany.net (192.1.3.2)  PIM  thresh^ 1  
 -3  hostA.lab.mycompany.net (192.1.4.2)
Round trip time 2 ms; total ttl of 2 required.