Tracing PIM Packets

Problem

As part of debugging the operation of PIM, you want to trace all PIM packets exchanged by your router.

Solution

Enable PIM packet tracing:

	[edit protocols 
pim]
	aviva@RouterA# set traceoptions file pim-trace world-readable
	aviva@RouterA# set traceoptions flag packets

Discussion

As you are setting up and debugging a PIM domain, you can turn on tracing on PIM to keep a log of packet exchanges between routers. The option you choose depends on what you are interested in logging at any particular time. With JUNOS PIM, you can trace the following:

	[edit protocols pim traceoptions]
	aviva@RouterA# set flag ?
	Possible completions:
	 all Trace everything
	 assert Trace assert messages
	 autorp Trace bootstrap/RP/auto-RP messages
	 bootstrap Trace bootstrap/RP/auto-RP messages
	 general Trace general events
	 graft Trace join/prune/graft/graft-ack messages
	 hello Trace hello packets
	 join Trace join/prune/graft/graft-ack messages
	 mdt Trace messages related to multicast data tunnels
	 normal Trace normal events
	 packets Trace all 
PIM packets
	 policy Trace policy processing
	 prune Trace join/prune/graft/graft-ack messages
	 register Trace register/register-stop messages
	 route Trace routing information
	 rp Trace bootstrap/RP/auto-RP messages
	 state Trace state transitions
	 task Trace routing protocol task processing
	 timer Trace routing protocol timer processing

The trace options let you track all PIM operations and packets. More useful is being able to trace specific packet types, such as Join/Prune messages and auto-RP messages. You can also select additional options, to get either detailed traces or limit the traces only to packets sent or received by the router:

	aviva@RouterA# set flag join ?
	Possible completions:
	 <[Enter]> Execute this command
	 detail Trace detailed information
	 disable Disable this trace flag
	 receive Trace received packets
	 send Trace transmitted packets

The command in this recipe is a simple example of tracing all PIM packets to a file named pim-trace. As soon as you commit the configuration, the file starts recording PIM messages:

	aviva@RouterA> show log pim-trace
	Nov 30 20:21:54 trace_on: Tracing to "/var/log/pim-trace" started
	Nov 30 20:22:01 PIM se-0/0/3.0 RECV 10.0.16.2 -> 224.0.0.13 V2 JoinPrune to 10.0.16.1
	holdtime 210 groups 1 sum 0xc0e6 len 34
	Nov 30 20:22:03 PIM fe-0/0/1.0 RECV 10.0.15.1 -> 224.0.0.13 V2 Hello hold 105 T-bit
	LAN prune 500 ms override 2000 ms pri 1 genid 300123470 sum 0xbe67 len 34
	Nov 30 20:22:14 PIM fe-0/0/1.0 SENT 10.0.15.2 -> 224.0.0.13 V2 Bootstrap sum 0x46d4
	len 36
	Nov 30 20:22:14 PIM se-0/0/3.0 SENT 10.0.16.1 -> 224.0.0.13 V2 Bootstrap sum 0x46d4
	len 36
	Nov 30 20:22:14 PIM se-0/0/2.0 SENT 10.0.21.1 -> 224.0.0.13 V2 Bootstrap sum 0x46d4
	len 36
	Nov 30 20:22:14 PIM se-0/0/3.0 RECV 10.0.16.2 -> 224.0.0.13 V2 JoinPrune to 10.0.16.1
	holdtime 210 groups 4 sum 0x4406 len 102
	Nov 30 20:22:14 PIM fe-0/0/1.0 RECV 10.0.15.1 -> 224.0.0.13 V2 JoinPrune to 10.0.15.2
	holdtime 210 groups 2 sum 0x5203 len 54

This output records PIM Join/Prune, Hello, and Bootstrap messages.

See Also

Recipe 5.10

About the Author

Aviva Garrett has documented Juniper Networks technologies since joining the company as its first writer in 1997. She wrote the first JUNOS manuals and then oversaw the documentation as the company grew from a startup to an established network equipment provider. She recently stepped down as the Juniper Networks Director of Technical Publications to pursue other writing and business assignments, such as JUNOS Cookbook. Prior to Juniper Networks, Aviva worked at Cisco Systems for six years. She also worked for Excelan/Novell, Gavilan, and other technology companies and startups. She is the coauthor of Juniper Networks Field Guide and Reference (Addison-Wesley).