Using the mtrace from-source Command

To display information about a multicast path from a source to the Services Router, enter the mtrace from-source command with the following syntax. Table 206 describes the mtrace from-source command options.

user@host> mtrace from-source source host <extra-hops number> <group address> <interval seconds> <max-hops number> <max-queries number> <response host> <routing-instance routing-instance-name> <ttl number> <wait-time seconds> <loop> <multicast-response | unicast-response> <no-resolve> <no-router-alert> <brief | detail>

Table 206: CLI mtrace from-source Command Options

Option

Description

source host

Traces the path to the specified hostname or IP address.

extra-hops number

(Optional) Sets the number of extra hops to trace past nonresponsive routers. Specify a value from 0 through 255.

group address

(Optional) Traces the path for the specified group address. The default value is 0.0.0.0.

interval seconds

(Optional) Sets the interval between statistics gathering. The default value is 10.

max-hops number

(Optional) Sets the maximum number of hops to trace toward the source. Specify a value from 0 through 255. The default value is 32.

max-queries number

(Optional) Sets the maximum number of query attempts for any hop. Specify a value from 1 through 32. The default value is 3.

response host

(Optional) Sends the response packets to the specified hostname or IP address. By default, the response packets are sent to the Services Router.

routing-instance routing-instance-name

(Optional) Traces the routing instance you specify.

ttl number

(Optional) Sets the time-to-live (TTL) value in the IP header of the query packets. Specify a hop count from 0 through 255. The default value for local queries to the all routers multicast group is 1. Otherwise, the default value is 127.

wait-time seconds

(Optional) Sets the time to wait for a response packet. The default value is 3 seconds.

loop

(Optional) Loops indefinitely, displaying rate and loss statistics. To quit the mtrace command, press Ctrl-C.

multicast-response

(Optional) Forces the responses to use multicast.

unicast-response

(Optional) Forces the response packets to use unicast.

no-resolve

(Optional) Does not display hostnames.

no-router-alert

(Optional) Does not use the router alert IP option in the IP header.

brief

(Optional) Does not display packet rates and losses.

detail

(Optional) Displays packet rates and losses if a group address is specified.

Following is sample output from the mtrace from-source command:

user@host> mtrace from-source source 192.1.4.1 group 224.1.1.1

Mtrace from 192.1.4.1 to 192.1.30.2 via group 224.1.1.1 Querying full reverse path... * *    0  ? (192.1.30.2)  -1  ? (192.1.30.1)  PIM  thresh^ 1    -2  routerC.mycompany.net (192.1.40.2)  PIM  thresh^ 1    -3  hostA.mycompany.net (192.1.4.1) Round trip time 22 ms; total ttl of 2 required.  Waiting to accumulate statistics...Results after 10 seconds:    Source        Response Dest    Overall     Packet Statistics For Traffic From 192.1.4.1  192.1.30.2       Packet      192.1.4.1 To 224.1.1.1      v       __/  rtt   16 ms     Rate       Lost/Sent = Pct  Rate 192.168.195.37  192.1.40.2      routerC.mycompany.net       v     ^      ttl    2                      0/0    = --    0 pps 192.1.40.1      192.1.30.1      ?                    v      /__   ttl    3                      ?/0            0 pps 192.1.30.2      192.1.30.2   Receiver      Query Source

Each line of the trace display is usually in the following format (depending on the options selected and the responses from the routers along the path):

hop-number host (ip-address) protocolttl

Table 207 summarizes the output fields of the display.

Note: The packet statistics gathered from Juniper Networks routers and routing nodes are always displayed as 0.

Table 207: CLI mtrace from-source Command Output Summary

Field

Description

hop-number

Number of the hop (router) along the path.

host

Hostname, if available, or IP address of the router. If the no-resolve option was entered in the command, the hostname is not displayed.

ip-address

IP address of the router.

protocol

Protocol used.

ttl

TTL threshold.

Round trip time milliseconds ms

Total time between the sending of the query packet and the receiving of the response packet.

total ttl of number required

Total number of hops required to reach the source.

Source

Source IP address of the response packet.

Response Dest

Response destination IP address.

Overall

Average packet rate for all traffic at each hop.

Packet Statistics For Traffic From

Number of packets lost, number of packets sent, percentage of packets lost, and average packet rate at each hop.

Receiver

IP address receiving the multicast packets.

Query Source

IP address of the host sending the query packets.

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