Videoconferencing: Network Tools

1
Videoconferencing Network Tools Troubleshooting

• Egon Verharen
• TNC2004 H.323 training
• June 11, 2004
• Rhodes, Greece

2
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

3
Network Traffic Analyzers

• Reveals the traffic on a LAN
• Protocol analysis
• Reports such as utilization, protocols,
  conversations, nodes, etc.
• Software
• Ethereal http//ethereal.com/
• EtherPeek http//wildpackets.com/
• 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.

4
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

5
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
• Microsoft Windows tracert uses ICMPUnix
  traceroute uses UDP
• If Microsoft Windows tracert appears to show
  continuous timeouts, the router may be filtering
  ICMP traffic try a Unix/Linux traceroute.
• Identify the path, and then perform pings along
  the path segments to isolate troublesome
  segments.

6
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

7
Gnuplotping

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

8
MRTG.ORG

• Multi Router Traffic Grapher
• Open Source
• Collect and graph scalar, time-based data, e.g.,
  router and link performance data.

9
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 http//traceroute.org/

10
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.

11
NREN Detectives

• I2 Detective http//detective.internet2.edu/
• SURFnet Detectivehttp//detective.surfnet.nl/

12
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/

13
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/

14
Other Tools

• CAIDA Internet Measurement Tool Taxonomy
  http//www.caida.org/tools/taxonomy/measurement/

15
ViDe Videoconferencing Cookbook

• http//videnet.gatech.edu/cookbook/