Download 10_Tools_Troubleshooting

Videoconferencing: Network
Tools & Troubleshooting
Dave Devereaux-Weber
University of Wisconsin-Madison
Internet2 Commons Site Coordinator Training
September 27, 2004
Austin, Texas
Duplex Mismatch – Detection
 Show port statistics on the Ethernet switch. When
mismatched, the full-duplex end will report a high
level of CRC or alignment errors; the half-duplex
end will report a high number of late collisions.

Port
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Align
FCS Xmit
Rcv UnderSize
Err Err Err Err
2/11
-
0
0
3077
0
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Port Single- Multi- Late-
Coll
2/11 3233 0
Excess- CarriSen
Coll
Coll
Coll
2588
0
2489
0
Runts
Giants
0
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Ping
 Test for availability, loss, and roundtrip
time
 ICMP Echo Request
• Plus optional dummy payload – only in the
direction of the ping, i.e., source to destination
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Sample Ping from Windows
 C:\WINDOWS>ping 10.1.1.1
 Pinging 10.1.1.1 with 32 bytes of data:
 Reply from 10.1.1.1: bytes=32 time=88ms TTL=112
 Reply from 10.1.1.1: bytes=32 time=72ms TTL=112
 Reply from 10.1.1.1: bytes=32 time=69ms TTL=112
 Reply from 10.1.1.1: bytes=32 time=69ms TTL=112
 Ping statistics for 10.1.1.1:
 Packets: Sent = 4, Received = 4, Lost = 0 (0%
loss),
 Approximate round trip times in milli-seconds:

Minimum = 69ms, Maximum = 88ms, Average =
74ms
 C:\WINDOWS>
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Sample Ping from Windows
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C:\WINDOWS>ping -l 40000 10.1.1.1
Pinging 10.1.1.1 with 40000 bytes of data:
Reply from 10.1.1.1: bytes=40000 time=2412ms TTL=112
Reply from 10.1.1.1: bytes=40000 time=2721ms TTL=112
Reply from 10.1.1.1: bytes=40000 time=2761ms TTL=112
Reply from 10.1.1.1: bytes=40000 time=2714ms TTL=112
Ping statistics for 10.1.1.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0%
loss),
Approximate round trip times in milli-seconds:
Minimum = 2412ms, Maximum = 2761ms, Average =
2652ms
C:\WINDOWS>
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Ping Big and Fast on Linux
 ping -c2000 -i.03 -s1470 -q
[destination]
• Count of 2000 packets
• Interval of .03 seconds between packet starts
• Packet size of 1470 bytes
• (2000)(.03) = 60 second long test
• (1/(.03 sec/packet))(1470 bytes/packet)(8
bits/byte) = 392 Kbps
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Ping Big and Fast on Linux
 $ ping -c2000 -i.03 -s1470
[hostname]
-q
 PING [hostname] ([hostaddr]) from
[hostaddr2] : 1470(1498) bytes of data.
 --- [hostname] ping statistics -- 2000 packets transmitted, 2000 packets
received, 0% packet loss
 round-trip min/avg/max = 4.8/5.1/13.2
ms
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Traceroute
 Used to discover the layer-3 network path
(routers) between the two endpoints
 Doesn’t identify layer-2 devices (switches)
 Take baselines – know what your path
should be in advance of trouble
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Traceroute
 Microsoft Windows tracert uses ICMP
 Unix traceroute uses UDP
 If Microsoft Windows tracert appears to
show continuous timeouts, the router
may be filtering ICMP traffic – try a
Unix/Linux traceroute.
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Traceroute; Sample Output
 [dodpears@huck dodpears]$ traceroute www.internet2.edu
 traceroute to www.internet2.edu (209.211.239.208), 30 hops max, 38 byte
packets
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1 wcc-sub5-hp1 (129.79.5.253) 11.726 ms 0.627 ms 0.571 ms
2 iub-gw (129.79.8.10) 3.133 ms 0.717 ms 0.651 ms
3 156.56.249.22 (156.56.249.22) 2.544 ms 3.138 ms 2.538 ms
4 abilene-iupui.abilene.ucaid.edu (198.32.11.13) 5.245 ms 3.402 ms
3.493 ms
 5 clev-ipls.abilene.ucaid.edu (198.32.8.26) 9.381 ms 9.586 ms 9.244 ms
 6 nycm-clev.abilene.ucaid.edu (198.32.8.30) 23.198 ms 21.963 ms
21.775 ms
 7 border-abilene-oc3.advanced.org (209.211.237.97) 23.448 ms 23.268
ms 23.052 ms
 8 www.internet2.edu (209.211.239.208) 23.559 ms 23.478 ms 23.234 ms
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Traceroute
 8 www.internet2.edu (209.211.239.208) 23.559 ms 23.478 ms 23.234
ms
 Hop
 Router/host name

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Router/host address
Round-trip times of each of three probes
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Traceroute – Example Uses
 Identify the path, and then perform
pings along the path segments to
isolate troublesome segments.
 Insure that Internet2 is being used for a
connection, rather than commercial
Internet.
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Looking Glass
These network tools work from your
vantage point out; what if you want to
measure from some other vantage point
back in? You want a looking glass:
See traceroute.org
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Ping Plotter
 Shareware tool; $15
• http://www.pingplotter.com
 Performs a visual traceroute and ping
tests along the entire path
 Permits identification of bottlenecks
along a path
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Ping Plotter
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MRTG.ORG
 Multi Router Traffic Grapher
 Open Source
 Collect and graph scalar, time-based
data, e.g., router and link performance
data.
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MRTG Example
MRTG graph showing traffic from SLAC to a
physics lab at University of Wisconsin
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Iperf
 Client/server application that
• Measures maximum TCP bandwidth
• Facilitates tuning of TCP and UDP parameters
• Reports bandwidth, jitter, and packet loss
 http://dast.nlanr.net/Projects/Iperf/
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Iperf
Example on Intercampus DS3
At server, invoke:
iperf -fk -i30 -u -s
(f)ormat reports in kbps
(i)nterval for reporting = 30 seconds
(u)dp
(s)erver mode
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Gnuplotping
 Pings multiple hosts in parallel with
graphical display (gnuplot) of the delay
distribution.
 Runs on Unix/X-Windows
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Gnuplotping
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Network Traffic Analyzer
 Reveals the traffic on a LAN
 Protocol analysis
 Reports such as utilization, protocols,
conversations, nodes, etc.
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Network Traffic Analyzer: Software
Ethereal http://ethereal.com/
EtherPeek http://wildpackets.com/
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Network Traffic Analyzer:
Commercial Hardware
Fluke Networks NetTool
http://www.flukenetworks.com/us/LAN/Handheld+Testers/NetTool/Overview.htm This
is a technician-oriented tool to perform diagnostics and testing.
 Fluke has an excellent white paper on auto-negotiation problems. Highly
recommended.
Network Associates Sniffer
http://nai.com/
This is an engineer-oriented tool to analyze packets and traffic- often needs
interpretation.
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Internet2 Detective
 I2 Detective is a small application.
 Very easy to use
 Detects Internet2 connection.
 Measures connection bandwidth (using
Iperf).
 Detects multicast connection.
• http://detective.internet2.edu/
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ANL Web100 based Network
Diagnostic Tester (NDT)
 Highly recommended
 http://miranda.ctd.anl.gov:7123/
• Located at Argonne National Laboratory; 100 Mbps
FastEthernet network connection
This java applet was developed to test the reliability and
operational status of your desktop computer and network
connection. It does this by sending data between your computer
and this remote NDT server. These tests will determine:
• The slowest link in the end-to-end path (Dial-up modem to 10 Gbps
Ethernet/OC-192)
• The Ethernet duplex setting (full or half);
• If congestion is limiting end-to-end throughput.
It can also identify 2 serious error conditions:
• Duplex Mismatch
• Excessive packet loss due to faulty cables.
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H.323 Beacon
 Open Source Software
 Used to measure, monitor and qualify the
performance of an H.323 Videoconference
session.
 Provides H.323-protocol specific evidence
and other information necessary to
troubleshoot H.323 application performance
problems in the network and at the host
(end-to-end)
• http://www.itecohio.org/beacon/
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Other Tools
CAIDA Internet Measurement Tool
Taxonomy
http://www.caida.org/tools/taxonomy/measurement/
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ViDe Videoconferencing Cookbook
 http://videnet.gatech.edu/cookbook/
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The Network
Information on these slides courtesy of
Doug Pearson
Indiana University
And
David Devereaux-Weber
University of Wisconsin-Madison
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