What's this?

Watching Mars Pathfinder coverage from NASA via the MBone, I noticed that audio quality, limited by packet loss rate, was sometimes much better than at other times. RTP loss statistics from vat(1) showed that the bulk of the packet loss recurred periodically, with a period around 70-75 seconds. The cyclic loss varies in intensity, but persists from day to day, week to week. Where was this loss coming from, and why was it so neatly periodic?

The main tool for examining the state of the multicast Internet is mtrace(1).

It was used here in the form

mtrace -l   NASA-MBone-source   some-remote-receiver   multicast-address
and left to run for a while. mtrace -l traces out the path from the source to the receiver (assumed to be a member of the given multicast group, i.e. to be currently listening in on that MBone broadcast) and gathers path and packet-loss statistics at 10-second intervals. These statistics are plotted below.

For each graph, there's a table of MBone routers in order from source to receiver (hop 0 being the source, etc.). On the graph itself, the various MBone routers are ordered by the range of measured variation in the packet-loss rate, with the widest-swinging MBone router being first.


Contents

Some mtrace results from the evening of 7/22/97

Also, see these mtrace -g's from afternoon of 7/23

Please send questions or comments to Stuart Levy, slevy@geom.umn.edu, Geometry Center, University of Minnesota.


Code

All these were generated with
mdecode -s -h mtrace-output >> stuff.html
for each mtrace file in turn. The table-of-contents header was added by hand.


Results

nasa-delmarva -- Mtrace from 128.102.84.134 to 138.39.5.48 via group 224.2.210.20

(raw data, GNUplot commands, GNUplot data.)

Nodes, with loss variation (percent over mtrace -l's 10-second intervals):

Hop  0  loss  0.. 0%  224.0.1.32
Hop  1  loss -5.. 5%  arcbone.arc.nasa.gov
Hop  2  loss -1.. 2%  ARC-MBONE.NSN.NASA.GOV
Hop  3  loss  0..20%  FIXW-MBONE.NSN.NASA.GOV
Hop  4  loss  0.. 4%  dec3800-2-fddi-1.SanFrancisco.mci.net
Hop  5  loss  0.. 3%  dec3800-1-fddi-1.Dallas.mci.net
Hop  6  loss  0.. 2%  dec3800-2-fddi-1.Atlanta.mci.net
Hop  7  loss  0.. 2%  dec3800-1-fddi-1.NorthRoyalton.mci.net
Hop  8  loss -1.. 2%  dec3800-1-fddi-1.WestOrange.mci.net
Hop  9  loss  0.. 0%  multicast.delmarva.com
Hop 10  loss  0.. 0%  128.101.25.56

nasa-dk -- Mtrace from 128.102.84.134 to 130.225.16.85 via group 224.2.210.20

(raw data, GNUplot commands, GNUplot data.)

Nodes, with loss variation (percent over mtrace -l's 10-second intervals):

Hop  0  loss  0.. 0%  224.0.1.32
Hop  1  loss  0.. 1%  arcbone.arc.nasa.gov
Hop  2  loss  0.. 0%  ARC-MBONE.NSN.NASA.GOV
Hop  3  loss -4..30%  FIXW-MBONE.NSN.NASA.GOV
Hop  4  loss  0.. 2%  dec3800-2-fddi-1.SanFrancisco.mci.net
Hop  5  loss  0.. 1%  dec3800-1-fddi-1.Dallas.mci.net
Hop  6  loss  0.. 3%  dec3800-2-fddi-1.Atlanta.mci.net
Hop  7  loss  0.. 1%  dec3800-1-fddi-1.NorthRoyalton.mci.net
Hop  8  loss  0.. 1%  dec3800-1-fddi-0.WestOrange.mci.net
Hop  9  loss -3.. 4%  schnell.ebone.net
Hop 10  loss -2.. 3%  stockholm.mbone.ebone.net
Hop 11  loss  0.. 0%  patella.uni-c.dk
Hop 12  loss  0.. 0%  rhodium.daimi.aau.dk
Hop 13  loss  0.. 0%  128.101.25.56

nasa-geom -- Mtrace from 128.102.84.134 to 128.101.25.56 via group 224.2.210.20

(raw data, GNUplot commands, GNUplot data.)

Nodes, with loss variation (percent over mtrace -l's 10-second intervals):

Hop  0  loss  0.. 0%  224.0.1.32
Hop  1  loss -5.. 7%  arcbone.arc.nasa.gov
Hop  2  loss  0.. 0%  ARC-MBONE.NSN.NASA.GOV
Hop  3  loss  0..24%  FIXW-MBONE.NSN.NASA.GOV
Hop  4  loss -1.. 6%  dec3800-2-fddi-1.SanFrancisco.mci.net
Hop  5  loss -1.. 6%  dec3800-2-fddi-1.Denver.mci.net
Hop  6  loss  0.. 7%  dec3800-1-fddi-1.WillowSprings.mci.net
Hop  7  loss -1.. 4%  bridge.mr.net
Hop  8  loss  0.. 0%  hausdorff.geom.umn.edu
Hop  9  loss  0.. 0%  128.101.25.56

nasa-isi -- Mtrace from 128.102.84.134 to 128.9.80.62 via group 224.2.210.20

(raw data, GNUplot commands, GNUplot data.)

Nodes, with loss variation (percent over mtrace -l's 10-second intervals):

Hop  0  loss  0.. 0%  224.0.1.32
Hop  1  loss -4.. 6%  arcbone.arc.nasa.gov
Hop  2  loss  0.. 0%  ARC-MBONE.NSN.NASA.GOV
Hop  3  loss -1..25%  FIXW-MBONE.NSN.NASA.GOV
Hop  4  loss  0.. 2%  dec3800-2-fddi-0.SanFrancisco.mci.net
Hop  5  loss  0.. 1%  dec3800-1-fddi-0.LosAngeles.mci.net
Hop  6  loss  0.. 5%  mbone.ln.net
Hop  7  loss  0.. 0%  mb80.isi.edu
Hop  8  loss  0.. 0%  128.101.25.56

nasa-lbl -- Mtrace from 128.102.84.134 to 131.243.48.193 via group 224.2.210.20

(raw data, GNUplot commands, GNUplot data.)

Nodes, with loss variation (percent over mtrace -l's 10-second intervals):

Hop  0  loss  0.. 0%  224.0.1.32
Hop  1  loss -9..10%  arcbone.arc.nasa.gov
Hop  2  loss  0.. 1%  ARC-MBONE.NSN.NASA.GOV
Hop  3  loss -3.. 4%  FIXW-MBONE.NSN.NASA.GOV
Hop  4  loss -3.. 1%  mbone.nsi.nasa.gov
Hop  5  loss  0.. 0%  llnl-mr2.es.net
Hop  6  loss  0.. 0%  lbl-mr1-f.es.net
Hop  7  loss  0.. 0%  er1gw.lbl.gov
Hop  8  loss  0.. 0%  ir40gw.lbl.gov
Hop  9  loss  0.. 0%  128.101.25.56

nasa-sdsc -- Mtrace from 128.102.84.134 to 138.18.5.224 via group 224.2.210.20

(raw data, GNUplot commands, GNUplot data.)

Nodes, with loss variation (percent over mtrace -l's 10-second intervals):

Hop  0  loss  0.. 0%  224.0.1.32
Hop  1  loss -15..14%  arcbone.arc.nasa.gov
Hop  2  loss  0.. 0%  ARC-MBONE.NSN.NASA.GOV
Hop  3  loss  0.. 1%  FIXW-MBONE.NSN.NASA.GOV
Hop  4  loss  0.. 0%  nccosc-mbone.dren.net
Hop  5  loss  0.. 0%  128.101.25.56

nasa-worldcom -- Mtrace from 128.102.84.134 to 207.247.31.7 via group 224.2.210.20

(raw data, GNUplot commands, GNUplot data.)

Nodes, with loss variation (percent over mtrace -l's 10-second intervals):

Hop  0  loss  0.. 0%  224.0.1.32
Hop  1  loss  0.. 0%  arcbone.arc.nasa.gov
Hop  2  loss  0.. 0%  ARC-MBONE.NSN.NASA.GOV
Hop  3  loss  0..25%  FIXW-MBONE.NSN.NASA.GOV
Hop  4  loss  0.. 3%  dec3800-2-fddi-1.SanFrancisco.mci.net
Hop  5  loss  0.. 1%  dec3800-1-fddi-1.Dallas.mci.net
Hop  6  loss  0.. 3%  dec3800-2-fddi-1.Atlanta.mci.net
Hop  7  loss -1.. 2%  atlanta3-mbone1.bbnplanet.net
Hop  8  loss  0.. 6%  collegepk-mbone1.bbnplanet.net
Hop  9  loss  0.. 2%  cambridge1-mbone1.bbnplanet.net
Hop 10  loss -1.. 3%  MBONE3.UU.NET
Hop 11  loss  0.. 0%  st6.wcomcast.com
Hop 12  loss  0.. 0%  128.101.25.56

Path changed during tracing...

(raw data, GNUplot commands, GNUplot data.)

Nodes, with loss variation (percent over mtrace -l's 10-second intervals):

Hop  0  loss  0.. 0%  224.0.1.32
Hop  1  loss  0.. 1%  arcbone.arc.nasa.gov
Hop  2  loss  0.. 0%  ARC-MBONE.NSN.NASA.GOV
Hop  3  loss  0.. 3%  maew-mbone.nsn.nasa.gov
Hop  4  loss 16..94%  sanjose1-mbone1.bbnplanet.net
Hop  5  loss -24.. 0%  paloalto-mbone1.bbnplanet.net
Hop  6  loss -7..10%  collegepk-mbone1.bbnplanet.net
Hop  7  loss  0.. 2%  cambridge1-mbone1.bbnplanet.net
Hop  8  loss -2.. 2%  MBONE3.UU.NET
Hop  9  loss  0.. 0%  st6.wcomcast.com
Hop 10  loss  0.. 0%  128.101.25.56

Path changed during tracing...

(raw data, GNUplot commands, GNUplot data.)

Nodes, with loss variation (percent over mtrace -l's 10-second intervals):

Hop  0  loss  0.. 0%  cambridge1-mbone1.bbnplanet.net
Hop  1  loss  0.. 0%  MBONE3.UU.NET
Hop  2  loss  0.. 0%  st6.wcomcast.com
Hop  3  loss  0.. 0%  128.101.25.56

Path changed during tracing...

(raw data, GNUplot commands, GNUplot data.)

Nodes, with loss variation (percent over mtrace -l's 10-second intervals):

Hop  0  loss  0.. 0%  224.0.1.32
Hop  1  loss -4.. 5%  arcbone.arc.nasa.gov
Hop  2  loss -2.. 3%  ARC-MBONE.NSN.NASA.GOV
Hop  3  loss  0.. 0%  maew-mbone.nsn.nasa.gov
Hop  4  loss  0.. 0%  mbone-w.ans.net
Hop  5  loss  0.. 0%  mbone-e.ans.net
Hop  6  loss  0.. 0%  collegepk-mbone1.bbnplanet.net
Hop  7  loss  0.. 0%  cambridge1-mbone1.bbnplanet.net
Hop  8  loss  0.. 0%  MBONE3.UU.NET
Hop  9  loss  0.. 0%  st6.wcomcast.com
Hop 10  loss  0.. 0%  128.101.25.56

Path changed during tracing...

(raw data, GNUplot commands, GNUplot data.)

Nodes, with loss variation (percent over mtrace -l's 10-second intervals):

Hop  0  loss  0.. 0%  224.0.1.32
Hop  1  loss  0.. 0%  arcbone.arc.nasa.gov
Hop  2  loss  0.. 0%  ARC-MBONE.NSN.NASA.GOV
Hop  3  loss  0.. 0%  FIXW-MBONE.NSN.NASA.GOV
Hop  4  loss  0.. 1%  mbone.nsi.nasa.gov
Hop  5  loss  0.. 3%  stk-mbone-1.sprintlink.net
Hop  6  loss  0.. 7%  fw-mbone-1.sprintlink.net
Hop  7  loss -99.. 0%  dc-mbone-1.sprintlink.net
Hop  8  loss 21..28%  pen-mbone-1.sprintlink.net
Hop  9  loss  0.. 1%  mbone1.nap.net
Hop 10  loss -1.. 2%  MBONE3.UU.NET
Hop 11  loss  0.. 0%  st6.wcomcast.com
Hop 12  loss  0.. 0%  128.101.25.56

Path changed during tracing...

(raw data, GNUplot commands, GNUplot data.)

Nodes, with loss variation (percent over mtrace -l's 10-second intervals):

Hop  0  loss  0.. 0%  224.0.1.32
Hop  1  loss  0.. 1%  arcbone.arc.nasa.gov
Hop  2  loss  0.. 0%  ARC-MBONE.NSN.NASA.GOV
Hop  3  loss  0..21%  FIXW-MBONE.NSN.NASA.GOV
Hop  4  loss -1.. 3%  dec3800-2-fddi-1.SanFrancisco.mci.net
Hop  5  loss -1.. 2%  dec3800-1-fddi-1.Dallas.mci.net
Hop  6  loss  0.. 3%  dec3800-2-fddi-1.Atlanta.mci.net
Hop  7  loss -2.. 2%  atlanta3-mbone1.bbnplanet.net
Hop  8  loss -1.. 4%  collegepk-mbone1.bbnplanet.net
Hop  9  loss -1.. 3%  cambridge1-mbone1.bbnplanet.net
Hop 10  loss -2.. 5%  MBONE3.UU.NET
Hop 11  loss  0.. 0%  st6.wcomcast.com
Hop 12  loss  0.. 0%  128.101.25.56