Subject: mtrace from inside on MOSPF cloud?

From: Anindo Banerjea <[email-masked]>
Date: Thu, 12 Dec 1996 16:48:39 -0500

Hi,

I was trying to run mtrace from my machine (bhaskara.comm.toronto.edu)
and having no luck at all. It turns out that the routers in our campus
run MOSPF, and there is a tunnel from the cloud to the MBONE.

The router is a
	Proteon RBX200

Here is the version of the software (OpenROUTE) and hardware
straight from the machine:

Portable M68360 C Gateway mbone.gw S/N 842
OpenROUTE (tm) 2.1a (16.1a[])
Boot ROM version  1.40     Watchdog timer enabled    Auto-boot enabled
Time: 10:43:37    Thursday  December 12, 1996       Console baud rate: 9600

My question is can I possibly get some useful information out
of mtrace or mrtree or similiar beasts under these circumstances?

So far I have had no luck. mrtree seems to indicate that the router
(who I know from tcpdump is originating the mcast packets on my
subnet) does not have the brains to pass the query further. This is
not too surprising considering mrtree appears to assume dvmrp and
if the router is running MOSPF....

But it looks like I should be able to query a router further away
by specifying that as the host. But if I do that I get no response
at all.

# ./mrtree 128.100.10.2
Potential distribution tree from 128.100.10.2...
 0 128.100.10.2 (128.100.10.2) [ver 1.0] ?
# ./mrtree 128.100.10.2 224.2.212.186 128.100.10.9
Actual distribution tree rooted at 128.100.10.2 for group 224.2.212.186 and source 128.100.10.9...
 0 128.100.10.2 (128.100.10.2) [ver 1.0] ?
# ./mrtree mbone.merit.edu
Potential distribution tree from mbone.merit.edu...
#

mtrace does no better. If I specify my host as the destination it gets no
response from my router and stops. This I can understand. But if
I specify a remote src and destination (I tried the NASA shuttle audio
while it was going on last week and picked some of the receivers who
were listening to it) I would expect some response from the gatewat
one hop away from the receiver if I set the ttl large enough. But no
such luck.

For example, I pick two people who are logged into the FreeBSD audio session
right now and generate an mtrace between them.

# ../mrouted/mtrace -t 200 -i 128.100.10.9 -q 10 129.89.142.50 198.252.159.14 224.2.100.100
Mtrace from 129.89.142.50 to 198.252.159.14 via group 224.2.100.100
Querying full reverse path... * switching to hop-by-hop:
  0  moonpie.w8hd.org (198.252.159.14)
 -1  * * * * * * * * * * Timed out receiving responses
Perhaps receiver 198.252.159.14 is not a member of group 224.2.100.100,
or no router local to it has a route for source 129.89.142.50,
or multicast at ttl 200 doesn't reach its last-hop router for that source

Any enlightened souls who can enlighten me?

Anindo

---

From: Tom Pusateri <[email-masked]>
Date: Thu, 12 Dec 1996 22:40:13 -0500

>run MOSPF, and there is a tunnel from the cloud to the MBONE.

Ask your router vendor to support mtrace. Its independent of which
multicast routing protocol you are using.

Tom

---

From: Bill Fenner <[email-masked]>
Date: Thu, 12 Dec 1996 20:37:46 PST

Anindo,

  Support of multicast traceroute depends on the router implementation,
not the routing protocol that is running.  It appears that your
Proteons do not support multicast traceroute.  Your best bet is to
contact Proteon and ask them to implement multicast traceroute in their
routers.

># ../mrouted/mtrace -t 200 -i 128.100.10.9 -q 10 129.89.142.50 198.252.159.14 

When mtrace is asked to do a third-party mtrace, it sends a multicast
query, so that the last-hop router can pick it up.  This did not work
because there is no route in the DVMRP routing table for 128.100.10.9,
so the multicast query could not get forwarded where it needed to go.

% mtrace -M -g dec2.hay.mci.net 128.100.10.9 dec2.hay.mci.net
Mtrace from 128.100.10.9 to 204.70.158.61 via group 224.2.0.1
Querying full reverse path... 
  0  dec3800-2-fddi-0.SanFrancisco.mci.net (204.70.158.61)
 -1  dec3800-2-fddi-0.SanFrancisco.mci.net (204.70.158.61)  No route
Round trip time 19 ms; total ttl of 2 required

This is probably an issue that you need to take up with the administrator
of the router that does the DVMRP/MOSPF gatewaying.

  Bill

---

From: Dave Thaler <[email-masked]>
Date: Fri, 13 Dec 1996 01:29:57 -0500 (EST)

> if the router is running MOSPF....

mrtree uses the DVMRP MIB for the potential (sub)tree, so yes that 
requires both DVMRP and SNMP at the router.  The actual tree uses the 
IP Multicast MIB, which also requires SNMP.  It also uses mrinfo (which
of course requires that the router support mrinfo) to allow it to
continue 1 hop beyond non-SNMP routers.

> mtrace does no better. If I specify my host as the destination it gets no

As Tom mentioned, this requires mtrace capability at the router.

So you need to find out whether your router supports mrinfo, mtrace,
and/or SNMP (the IP Multicast MIB in particular).  The more it supports,
the more info you can get.

-Dave