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Minutes from RIPE 38. Thanks to Rene Wilhelm once again.

  • To: "'tt-wg@localhost" < >
  • From: Keith Godber < >
  • Date: Mon, 26 Feb 2001 17:30:42 -0000
  • Cc: "'sylvana@localhost" < >

Draft minutes Test Traffic Working Group at RIPE 38

Chair    Keith Godber
Scribe   Rene Wilhelm

49 attendees

- -----------------------------


   1.Agenda Bashing 

   2.Introduction of new chair

   3.Status and plans, presentation by Henk Uijterwaal

   4.Data analysis, presentation Daniel Karrenberg

   5.GPS Site Survey tool, presentation by Florian Gruber



- -----------------------------

1. Agenda Bashing

   Agenda adopted without modification.

2. Introduction of new chair

   Matthew Robinson stepped down after the last meeting.
   Following a call to the tt-wg mailinglist, Keith Godber
   volunteered to take up this role.

3. Status and plans, presentation by Henk Uijterwaal

   [slides at ]

   Henk presented status of and future plans with Test Traffic Measurements

   TTM is now available as a membership service from RIPE NCC. As the tax 
   status is still under investigation, the service fee is currently set to
   EUR 0.0; hardware is provided against cost. Well defined analysis and
   research topics for next months.

   Questions & Answers:

   Q. Have you thought about adding a service like 'expected path'?
      Measure the path taken by packets between two boxes, notify user
      when it changes from what is expected. Would need a method to
      put the expected path in a database.
   A. We do have a database of traceroutes between all boxes.
      Good idea to raise alarm if path changes from expected one.

   Q. Testboxes rely on GPS, do you have alerting signal when quality is
   A. Yes, in the daily plots we color code the status of sender's and
      receiver's clock. We also have graphs and e-mailed lists of
      satellite reception conditions.

   Q. Can a test-box be used in a site's NTP service? would one have
      to contact RIPE NCC to enable it?
   A. Yes, a test-box may be used as stratum one time server in a site's
      network; no need to contact us, the service is available from the
      box as shipped. However, we do ask you to use it in a sensible way:
      only a limited number of machines (up to ~10) should peer directly
      with the test-box' NTP server; the rest of a site's machines should
      take time from these secondaries. In future we may need to put 
      passwords on the NTP service, secure it with encryption and enforce
      a maximum on the number of clients.

   Q. Do you have access lists to get to a box' data?
   A. Not at the moment, we want to add a service where people can get
      to latest results of a box in near real-time via http; that will
      require access control. All data are stored in a central database,
      we can configure from there, athough at this moment there's not
      much to configure (on request we provide data files via ftp).

   Q. Is there any process for analyzing the data we have? to learn
      traffic measurement variables?
   A. You can get the raw data from us, in ROOT format [];
      instructions and first steps with ROOT in the framework of TTM
      are posted on our website. Upon request we put the data on our 
      ftp site. If you have analysis code you find useful, we can discuss
      it in the test-traffic working group and include it the daily TTM
      analysis job.

   Q. Do you have experience with Denial of Service attacks to test-boxes?
   A. No.
   Q. Are you prepared?
   A. If we see it we react appropriately. Not many running services
      on the test-boxes.
   Q. But what about ICMP or UDP storms? These could disable a box.
   A. Yes, but one would see these on more of the site's network(s),
      not only the test-box would be affected.
   R. Still your naming scheme makes it relatively easy for hackers
      to guess a test-box name; suggest to switch to a naming scheme
      that hides the purpose (TT measurements) of the box.

   Q. Do you have a map which shows location of test-boxes?
   A. Yes, available from the member pages.   
   Q. As antenna is outside, what about weather conditions? ice, lightning?
   A. Snow and rain do not affect antenna itself; it comes as a sealed unit
      which can be submerged in water. The connector, however, might get
      damaged, as it is accessible on the outside.  Usually, the problem
      will be liquids which could cause short circuits; easily solved by
      disconnecting the connecting plug and letting it dry.

      Lightning: any lightning protection will help, do not make antenna
      highest point on the building. Note that it is the host's
      to make it compliant with the local lightning protection scheme. As
      country has its own regulations in this area, it is very hard to do
      coordinate that from Amsterdam.

4. Data analysis, presentation Daniel Karrenberg

   [slides at ]

   Daniel presented some of his findings from looking at the data
   over the last two weeks. The slides he showed illustrate what 
   interesting effects TTM can measure, and how the new plots-on-demand
   service can help zooming in to particular areas of interest.

   The precision the TTM tool can achieve was illustrated in the last
   slide, which showed a change pattern with amplitude of ~200 microseconds
   for delays between RIPE NCC office and Amsterdam Internet Exchange;
   these could be traced back to load balancing over the two different 
   circuits that connect the two sites.

   Questions & Answers

   Q. Can you report the number of changes in traceroutes as an
      indication of routing stability? would be especially useful
      to know when different paths have same number of hops.
   A. Yes, good idea, we'll implement this.

5. GPS Site Survey tool, presentation by Florian Gruber

   [slides at ]

   Florian talked about his work on a GPS site survey tool, which
   aims at assisting a test-box host in finding a good location for
   the GPS antenna before starting hard installation work. He also
   presented his experiences with various antenna positions.

   Questions & Answers

   Q. Windows sometimes work?
   A. Yes; if you don't have a possibility to put the antenna on the roof
      but do have a window facing south, in a high position it could work.
      However, you would have to monitor it for a longer time; the GPS
      satellites are not stationary with respect to earth, so good 
      conditions at one moment could evolve to bad conditions some hours

      Visibility of higher elevations is very important. On the outside
      of a window (wall mount) is much better than inside. Finally,
      the window will attenuate the signal; if coated with metal or
      other reflective material, it could even go to zero.

      General rule of thumb: if you can't get to the roof but can mount 
      the antenna on a southeast[*] wall, looking up, it will work.
      ([*] assuming you're on the northern hemisphere)

6. Competition 

   Only few entries were received for the 'renaming the project'
   No real winning catchy name, so it was agreed to stick with the old
   name of 'Test Traffic Measurements' and close this issue.

7. AOB 
   No other business; meeting closed.

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