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Videoconferencing: Network Tools

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Auto Speed, Duplex. Ports can be told to automatically ... Show port statistics on the ... white paper on auto-negotiation problems. Highly recommended. ... – PowerPoint PPT presentation

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Title: Videoconferencing: Network Tools


1
Videoconferencing Network Tools Troubleshooting
  • Dave Devereaux-Weber
  • University of Wisconsin-Madison
  • Internet2 Commons Site Coordinator Training
  • March 31, 2005
  • Atlanta, Georgia

2
Delay and Jitter
  • Delay is the elapsed time from send to receive
  • Jitter is variation in delay for each packet

3
Lost Packets
  • When a packet arrives too late to be displayed,
    the codec assumes it is lost. If network issues
    delay a packet, the codec calls it lost, but the
    router does not.

4
TCP and UDP
  • Transmission Control Protocol
  • This protocol guarantees receipt
  • Universal Datagram Protocol
  • This protocol does NOT guarantee receipt
  • Video is so time sensitive that retransmission
    does not help, so UDP is used
  • Email, WWW and file transfer use TCP
  • TCP can mask a poor connection, video shows all
    the network faults.

5
Duplex Mismatch
  • Using thicknet Ethernet, the same wire was used
    for sending and receiving if more than 1 talker
    at same time, packet errors.
  • Using twisted pair or fiber, different wire for
    transmit and receive, but ports need to be told
    to wait for quiet (half duplex) or talk anytime
    (full duplex).
  • Mismatch when 1 at half, 1 at full.

6
Auto Speed, Duplex
  • Ports can be told to automatically set speed
    duplex.
  • The standard says if you are in auto and the
    other end is not auto, drop to default of
    10/half.
  • The danger is that if 1 end is set for 100/full
    and the other is auto, the auto end, detecting
    non-auto on the other end must drop to 10/half

7
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 Align FCS Xmit Rcv UnderSize
  • Err Err Err Err
  • 2/11 - 0 0 3077 0
  • Port Single- Multi- Late- Excess- CarriSen Runts G
    iants
  • Coll Coll Coll Coll
  • 2/11 3233 0 2588 0 0 2489 0

8
Firewall
  • Consult your vendor website for firewall
    recommendations

9
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

10
Sample Ping from Windows
  • C\WINDOWSgtping 10.1.1.1
  • Pinging 10.1.1.1 with 32 bytes of data
  • Reply from 10.1.1.1 bytes32 time88ms TTL112
  • Reply from 10.1.1.1 bytes32 time72ms TTL112
  • Reply from 10.1.1.1 bytes32 time69ms TTL112
  • Reply from 10.1.1.1 bytes32 time69ms TTL112
  • 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\WINDOWSgt

11
Sample Ping from Windows
  • C\WINDOWSgtping -l 40000 10.1.1.1
  • Pinging 10.1.1.1 with 40000 bytes of data
  • Reply from 10.1.1.1 bytes40000 time2412ms
    TTL112
  • Reply from 10.1.1.1 bytes40000 time2721ms
    TTL112
  • Reply from 10.1.1.1 bytes40000 time2761ms
    TTL112
  • Reply from 10.1.1.1 bytes40000 time2714ms
    TTL112
  • 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\WINDOWSgt

12
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

13
Ping Big and Fast on Linux
  • ping -c2000 -i.03 -s1470 -q hostname
  • 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

14
Traceroute
  • Used to discover the layer-3 network path
    (routers) between the two endpoints
  • Doesnt identify layer-2 devices (switches)
  • Take baselines know what your path should be in
    advance of trouble

15
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.

16
Traceroute Sample Output
  • dodpears_at_huck dodpears traceroute
    www.internet2.edu
  • traceroute to www.internet2.edu
    (209.211.239.208), 30 hops max, 38 byte packets
  • 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

17
(No Transcript)
18
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.

19
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

20
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

21
Ping Plotter
22
MRTG.ORG
  • Multi Router Traffic Grapher
  • Open Source
  • Collect and graph scalar, time-based data, e.g.,
    router and link performance data.

23
MRTG Example
  • MRTG graph showing traffic from SLAC to a physics
    lab at University of Wisconsin

24
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/

25
IperfExample 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

26
Gnuplotping
  • Pings multiple hosts in parallel with graphical
    display (gnuplot) of the delay distribution.
  • Runs on Unix/X-Windows
  • http//www.gnuplot.info/

27
Gnuplotping
28
Network Traffic Analyzer
  • Reveals the traffic on a LAN
  • Protocol analysis
  • Reports such as utilization, protocols,
    conversations, nodes, etc.

29
Network Traffic Analyzer Software
  • Ethereal http//ethereal.com/
  • EtherPeek http//wildpackets.com/

30
Network Traffic Analyzer Commercial Hardware
  • Fluke Networks NetTool http//www.flukenetworks.co
    m/us/LAN/HandheldTesters/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.

31
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/

32
ANL Web100 based Network Diagnostic Tester (NDT)
  • Highly recommended
  • http//miranda.ctd.anl.gov7123/
  • 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.

33
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/

34
Other Tools
  • CAIDA Internet Measurement Tool Taxonomy
    http//www.caida.org/tools/taxonomy/measurement/
  • A comprehensive list of internet measurement tools

35
ViDe Videoconferencing Cookbook
  • http//videnet.gatech.edu/cookbook/
  • All about videoconferencing

36
Network Performance Advisor
  • From National Laboratory for Applied Network
    Research (NLANR)
  • http//dast.nlanr.net/projects/advisor/
  • The NLANR Network Performance Advisor is an
    easily customizable framework that provides a
    single application to integrate the measurement,
    analysis, and display of network performance
    statistics.
  • Free, open-source software

37
Chariot
  • Now IxChariot
  • http//www.ixiacom.com/products/performance_applic
    ations/pa_display.php?skeypa_ixchariotsectionpe
    rftest
  • Computer-based, distributed measurement with
    central control
  • Commercial software
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