[AG-TECH] multicast TALE OF WOE

Stephen Bosch sfbosch at netera.ca
Thu Sep 4 17:02:51 CDT 2003


Hi, everybody:

Okay -- I admit, this multicast stuff is Hungarian to me. I've installed 
mtrace, the kernel is configured for multicast, I'm supposed to be on a 
multicast-enabled network, but when I run the NLANR beacon, it looks 
like other sites can see me, but I am receiving nothing from them; this 
is clearly not a beacon problem, as AccessGrid stuff is not working 
either. At Todd Zimmerman's advice I tried to connect directly to 
NewMIC's venue, but got nothing.

I've included some diagnostic output below to help in identifying the 
problem:

root at accessgrid:/usr/src/linux-2.4.20# mtrace beaconserver.accessgrid.org
mtrace: WARNING: no multicast group specified, so no statistics printed
Mtrace from 140.221.9.160 to 206.75.91.40 via group 0.0.0.0
Querying full reverse path... * switching to hop-by-hop:
   0  accessgrid.netera.ca (206.75.91.40)
  -1  host206-75-91-33.netera.ca (206.75.91.33)  PIM/BGP4+  thresh^ 0
  -2  * * * c4-van01.canet4.net (205.189.32.198)  PIM  thresh^ 1
  -3  * * c4-win01.canet4.net (205.189.32.2)  PIM  thresh^ 1
  -4  * * c4-mren.canet4.net (205.189.32.69)  PIM/BGP4+  thresh^ 0
  -5  * * anl-mren-gige.anchor.anl.gov (192.5.170.213)  PIM  thresh^ 0
  -6  * * stardust-guava.anchor.anl.gov (130.202.222.73)  PIM  thresh^ 0
  -7  ag-tech.mcs.anl.gov (140.221.9.160)
Round trip time 80 ms; total ttl of 6 required.

COMMENT Seems to work only as far as our router.

root at accessgrid:~# mtrace beaconserver.accessgrid.org 206.75.91.40 
233.2.171.1
Mtrace from 140.221.9.160 to 206.75.91.40 via group 233.2.171.1
Querying full reverse path...
   0  accessgrid.netera.ca (206.75.91.40)
  -1  host206-75-91-33.netera.ca (206.75.91.33)  PIM  thresh^ 0  Reached 
RP/Core
Round trip time 1 ms; total ttl of 1 required.

Waiting to accumulate statistics...Results after 10 seconds:

   Source        Response Dest    Overall     Packet Statistics For 
Traffic From
    * * *        224.0.1.32       Packet      140.221.9.160 To 233.2.171.1
      v       __/  rtt    1 ms     Rate       Lost/Sent = Pct  Rate
206.75.91.33    host206-75-91-33.netera.ca Reached RP/Core
      v      \__   ttl    2         0 pps        ?/0            0 pps
206.75.91.40    206.75.91.40
   Receiver      Query Source

COMMENT: We are not receiving anything :)

root at accessgrid:~# mtrace ag.triumf.ca 206.75.91.40 233.2.171.1
Mtrace from 142.90.97.14 to 206.75.91.40 via group 233.2.171.1
Querying full reverse path...
   0  accessgrid.netera.ca (206.75.91.40)
  -1  host206-75-91-33.netera.ca (206.75.91.33)  PIM  thresh^ 0  Reached 
RP/Core
Round trip time 1 ms; total ttl of 1 required.

Waiting to accumulate statistics...Results after 10 seconds:

   Source        Response Dest    Overall     Packet Statistics For 
Traffic From
    * * *        224.0.1.32       Packet      142.90.97.14 To 233.2.171.1
      v       __/  rtt    1 ms     Rate       Lost/Sent = Pct  Rate
206.75.91.33    host206-75-91-33.netera.ca Reached RP/Core
      v      \__   ttl    2         0 pps        ?/0            0 pps
206.75.91.40    206.75.91.40
   Receiver      Query Source

root at accessgrid:~# mtrace cluster.vislab.usyd.edu.au 206.75.91.40 
233.2.171.1
Mtrace from 129.78.157.79 to 206.75.91.40 via group 233.2.171.1
Querying full reverse path...
   0  accessgrid.netera.ca (206.75.91.40)
  -1  host206-75-91-33.netera.ca (206.75.91.33)  PIM  thresh^ 0  Reached 
RP/Core
Round trip time 1 ms; total ttl of 1 required.

Waiting to accumulate statistics...Results after 10 seconds:

   Source        Response Dest    Overall     Packet Statistics For 
Traffic From
    * * *        224.0.1.32       Packet      129.78.157.79 To 233.2.171.1
      v       __/  rtt    1 ms     Rate       Lost/Sent = Pct  Rate
206.75.91.33    host206-75-91-33.netera.ca Reached RP/Core
      v      \__   ttl    2         0 pps        ?/0            0 pps
206.75.91.40    206.75.91.40
   Receiver      Query Source

eth1      Link encap:Ethernet  HWaddr 00:07:E9:18:CA:CA
           inet addr:206.75.91.40  Bcast:206.75.91.47 Mask:255.255.255.240
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:167845 errors:0 dropped:0 overruns:0 frame:0
           TX packets:1656033 errors:389 dropped:0 overruns:0 carrier:389
           collisions:57357 txqueuelen:100
           RX bytes:229841872 (219.1 Mb)  TX bytes:177592616 (169.3 Mb)
           Interrupt:19 Base address:0x2080 Memory:e8120000-e8140000


root at accessgrid:~# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use 
Iface
206.75.91.32    *               255.255.255.240 U     0      0        0 eth1
206.75.91.0     *               255.255.255.0   U     0      0        0 eth1
localnet        *               255.255.255.0   U     0      0        0 eth0
loopback        *               255.0.0.0       U     0      0        0 lo
224.0.0.0       *               240.0.0.0       U     0      0        0 eth1
default         host136-159-94- 0.0.0.0         UG    0      0        0 eth0


Anything here that looks suspicious? Note -- we get these results even 
when our non-multicast interface is disabled.

So -- is the problem on our machine, or is it a multicast routing problem?

Thanks for any help you can provide.

-Stephen-

-- 
Stephen Bosch
Collaborative Systems Specialist
Netera Alliance Inc.
Biosciences 530B
2500 University Dr NW
Calgary AB T2N 1N4
tel (403) 220 2546
fax (403) 282 0838




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