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{{TOCright}}[[Category:Network]]
While the [[Mesh_OLPC_Testbed|OLPC Mesh Testbed]] is conveniently located in the same space used by OLPC for development and business activities, it suffers from an excess of unrelated wireless traffic. In order to allow repeatable testing of larger numbers of laptops, a larger testbed has been set up at another location in the Boston area, where the 802.11b spectrum is relatively unused.
While the [[Mesh_OLPC_Testbed|OLPC Mesh Testbed]] is conveniently located in the same space used by OLPC for development and business activities, it suffers from an excess of unrelated wireless traffic. In order to allow repeatable testing of larger numbers of laptops, a larger testbed has been set up at another location in the Boston area, where the 802.11b spectrum is relatively unused.


= Test Setup =
= Test Setup =


At this location, we currently have a hundred laptops and a school server, along with a separate packet recording machine. Ten laptops are grouped together on each 1.5 m by 0.7 m table. We hope to grow to at least a hundred and fifty laptops over time.
At this location, we currently have a hundred [[Collab_Network_Test_Laptops|laptops]] and a school server, along with a separate packet recording machine. Ten laptops are grouped together on each 1.5 m by 0.7 m table. We hope to grow to at least a hundred and fifty laptops over time.


[[Image:PeabodyAnnex.png]]
[[Image:PeabodyAnnex.png]]
Line 10: Line 11:


The laptop developer keying, upgrading, and application installation is [[Peabody_Setup|done using USB keys]].
The laptop developer keying, upgrading, and application installation is [[Peabody_Setup|done using USB keys]].

<gallery>
Image:Collab_Network_Testbed_0101.JPG|The two rooms
Image:Collab_Network_Testbed_0099.JPG|Server/Monitoring Room
Image:Collab_Network_Testbed_0104.JPG|View into Front Room
Image:Collab_Network_Testbed_0103.JPG|Active Antennas
</gallery>


= Tests and Results =
= Tests and Results =


The tests are grouped according to the type of network used when they were performed: [[#Simple_Mesh|simple mesh]], a [[#School_Server_Mesh|mesh with a school server]], or [[#School_Server_WiFi|access points with a school server]].
The tests are grouped according to the type of network used when they were performed: [[Collab_Network_Simple_Mesh_Tests|simple mesh]], [[Collab_Network_Simple_Wifi_Tests|simple collaboration over managed WiFi]], a [[Collab_Network_School_Mesh_Tests|mesh with a school server]], or [[Collab_Network_School_Wifi_Tests|access points with a school server]].


All packet traces are in wireshark format, and contain beacon and link layer management frames as well as IP packets. They were obtained using <tt>tcpdump -i rtapX -w filename</tt>.
All packet traces are in wireshark format, and contain beacon and link layer management frames as well as IP packets. They were obtained using <tt>tcpdump -i rtapX -w filename</tt>.

More specifically, interfaces are configured to the appropriate channels at boot time via ifcfg_ethX files in <tt>/etc/sysconfig/network-scripts/</tt> (eth1 to channel 1, eth2 to channel 11, and eth3 to channel 6). There is a script, [http://xs-dev.laptop.org/mesh/test0321/setup_snoop setup_snoop], for setting up the interfaces which is run once after boot. Another, [http://xs-dev.laptop.org/mesh/test0321/do_snoop do_snoop], is used to start logging. Logging is stopped with <tt>sudo killall tcpdump</tt>


== Simple Mesh ==
== Simple Mesh ==


In these tests, the laptops are connected solely to one another, through the wireless mesh.
In these [[Collab_Network_Simple_Mesh_Tests|tests]], the laptops are connected solely to one another, through the wireless mesh. All presence and collaboration is Peer-to-Peer.


=== Startup ===
=== Startup ===
* [[Collab_Network_Simple_Mesh_Tests#Test_0317A|test 0317A]], 23 of 25 laptops join Simple Mesh

* [[Collab_Network_Simple_Mesh_Tests#Test_0331A|test 0331A]], 27 of 28 laptops join Simple Mesh
==== Test 0317A ====
* [[Collab_Network_Simple_Mesh_Tests#Test_0321C|test 0321C]], 20 of 21 laptops join Simple Mesh

* [[Collab_Network_Simple_Mesh_Tests#Test_0331B|test 0331B]], [[Collab_Network_Simple_Mesh_Tests#Test_0331C|test 0331C]], 28 of 28 laptops join Simple Mesh
'''Laptop Build:''' 699
* [[Collab_Network_Simple_Mesh_Tests#Test_0321A|test 0321A]], 10 of 10 laptops join Simple Mesh

=== Write sharing ===
This was a staged startup of laptops. The packet trace was started five minutes before starting to turn the laptops on. The laptops were turned on in groups of five, with each group allowed to enter simple mesh mode before starting the next group.
* [[Collab_Network_Simple_Mesh_Tests#Test_0331A|test 0331A]], 28 laptops, 5 of 7 succeed at joining Write

* [[Collab_Network_Simple_Mesh_Tests#Test_0321B|test 0321B]], 10 laptops, 9 of 9 succeed at joining Write
The first ten laptops (X50 - X59) came up without a problem, with all laptops able to see the others.
* [[Collab_Network_Simple_Mesh_Tests#Test_0317B|test 0317B]], 25 laptops, 7 of 10 succeed at joining Write

=== Read sharing ===
One laptop (X69) in the third group of laptops (X65 - X69) came up without joining a simple mesh ([http://dev.laptop.org/ticket/5848 Trac 5848]). A reboot fixed the problem.
* [[Collab_Network_Simple_Mesh_Tests#Test_0331C|test 0331C]], 28 laptops, 0 of 5 succeed at joining Read

* [[Collab_Network_Simple_Mesh_Tests#Test_0321A|test 0321A]], 10 laptops, 0 of 2 succeed at joining Read
Another laptop (X73) in the fifth group of laptops (X70 - X74) came up with [http://dev.laptop.org/ticket/5848 Trac 5848] and had to be rebooted before joining the simple mesh.
=== Chat ===

* [[Collab_Network_Simple_Mesh_Tests#Test_0331B|test 0331B]], 28 laptops, 6 of 11 succeed at Chat
After rebooting two laptops, all 25 laptops (X50 - X74) could see the other 24 in their neighborhood view.
* [[Collab_Network_Simple_Mesh_Tests#Test_0321C|test 0321C]], 21 laptops, 21 of 21 succeed at Chat

'''Packet Traces:''' [http://xs-dev.laptop.org/mesh/test0317/t0317_A_1.dump Chan 1], [http://xs-dev.laptop.org/mesh/test0317/t0317_A_11.dump Chan 11], [http://xs-dev.laptop.org/mesh/test0317/t0317_A_6.dump Chan 6]

[[Collab_Network_Test_0317A|Discussion of packet traces]]

=== Write Sharing ===

==== Test 0317B ====

'''Laptop Build:''' 699

This test started with 25 laptops (X50 - X74) in a simple mesh on channel 1.

The Write activity was started on laptop X69 (169.254.1.204), and shared with the neighborhood.

The shared activity was seen on 24 of 25 laptops (X70 not showing). After further shared activity, it was eventually seen by all 25 laptops.

Ten laptops joined the shared activity, almost simultaneously. Three of the ten laptops launched write, but never showed the contents of the write document. The other seven correctly mirrored the shared document.
The three laptops which failed to collaborate were X51 (169.254.5.153), X53 (169.254.2.7), and X54 (169.254.5.25).

More words were typed on X69, and were mirrored to the seven working laptops (no change in X51, X53, or X54).

Some words were typed on X59, and were correctly mirrored to the seven other collaborating laptops.

'''Packet Traces:''' [http://xs-dev.laptop.org/mesh/test0317/t0317_B_1.dump Chan 1], [http://xs-dev.laptop.org/mesh/test0317/t0317_B_11.dump Chan 11], [http://xs-dev.laptop.org/mesh/test0317/t0317_B_6.dump Chan 6]


== School Server Mesh ==
== School Server Mesh ==


In these tests, a school server equipped with one to three active antennas provides the interconnection for the laptops. In general, the laptops are registered with the school server and using the school's presence service.
In these [[Collab_Network_School_Mesh_Tests|tests]], a [[School server]] equipped with one to three [[Active Antenna]] provides the interconnection for the laptops. In general, the laptops are registered with the school server and using the school's presence service.


=== Startup & Registration ===
=== Startup & Registration ===
* [[Collab_Network_School_Mesh_Tests#Test_0414A|test 0414A]] 28 laptops
* [[Collab_Network_School_Mesh_Tests#Test_0414B|test 0414B]] 28 laptops
* [[Collab_Network_School_Mesh_Tests#Test_0414D|test 0414D]] 28 laptops
* [[Collab_Network_School_Mesh_Tests#Test_0323A|test 0323A]] 10 laptops
* [[Collab_Network_School_Mesh_Tests#Test_0323B|test 0323B]] 10 laptops
* [[Collab_Network_School_Mesh_Tests#Test_0323C|test 0323C]] 15 laptops
* [[Collab_Network_School_Mesh_Tests#Test_0323D|test 0323D]] 10 laptops
* [[Collab_Network_School_Mesh_Tests#Test_0323H|test 0323H]] 20 laptops
* [[Collab_Network_School_Mesh_Tests#Test_0317D|test 0317D]] 29 laptops
* [[Collab_Network_School_Mesh_Tests#Test_0317C|test 0317C]]
=== Presence ===
* [[Collab_Network_School_Mesh_Tests#Test_0321D|test 0321D]] 38 laptops
* [[Collab_Network_School_Mesh_Tests#Test_0317E|test 0317E]] 29 laptops
=== Chat ===
* [[Collab_Network_School_Mesh_Tests#Test_0323E|test 0323E]] 15 laptops
=== Write sharing ===
* [[Collab_Network_School_Mesh_Tests#Test_0321E|test 0414C]] 20 laptops
* [[Collab_Network_School_Mesh_Tests#Test_0321E|test 0414E]] 8 invites to another
* [[Collab_Network_School_Mesh_Tests#Test_0321E|test 0321E]]
=== Read sharing ===
* [[Collab_Network_School_Mesh_Tests#Test_0323F|test 0323F]] 10 laptops
* [[Collab_Network_School_Mesh_Tests#Test_0323G|test 0323G]] 10 laptops


==== Test 0317D ====
=== Startup Problems (#5963) ===


This table summarizes the tests done in search of information on [http://dev.laptop.org/ticket/4153 Trac ticket 4153] ([http://dev.laptop.org/ticket/5963 Trac ticket 5963] is a duplicate), an inability to reliably DHCP upon startup that impacts other use of the mesh as well. The information listed after each test is the number of laptops involved in the test, how they were started up (simultaneously or staggered in some way), and the number that successfully managed to find a school portal.
'''Laptop Build:''' 699


<table>
'''School Server Build:''' 160
<tr><th>Test</th><th>Num. Laptops</th><th>Timing</th><th>Spacing</th><th>Success</th><th>Comments</th></tr>
<tr align=center><td>[[Collab_Network_School_Mesh_Tests#Test_0323G|test 0323G]]</td><td>10</td><td>staged 5 sec</td><td>1 table</td><td>90%</td><td align=left></td></tr>
<tr align=center><td>[[Collab_Network_School_Mesh_Tests#Test_0323H|test 0323H]]</td><td>20</td><td>staged 7.5 sec</td><td>2 tables</td><td>90%</td><td align=left>groups of 2, 15 sec apart</td></tr>
<tr align=center><td>[[Collab_Network_School_Mesh_Tests#Test_0323E|test 0323E]]</td><td>15</td><td>staged 10 sec</td><td>spaced, 20 cm</td><td>87%</td><td align=left></td></tr>
<tr align=center><td>[[Collab_Network_School_Mesh_Tests#Test_0323B|test 0323B]]</td><td>10</td><td>simul.</td><td>spaced</td><td>80%</td><td align=left></td></tr>
<tr align=center><td>[[Collab_Network_School_Mesh_Tests#Test_0323F|test 0323F]]</td><td>10</td><td>simul.</td><td>1 table</td><td>80%</td><td align=left></td></tr>
<tr align=center><td>[[Collab_Network_School_Mesh_Tests#Test_0317D|test 0317D]]</td><td>29</td><td>grouped</td><td>3 tables</td><td>76%</td><td align=left>3 groups of 10, 5 min. apart</td></tr>
<tr align=center><td>[[Collab_Network_School_Mesh_Tests#Test_0323C|test 0323C]]</td><td>15</td><td>simul.</td><td>spaced, 30 cm.</td><td>73%</td><td align=left></td></tr>
<tr align=center><td>[[Collab_Network_School_Mesh_Tests#Test_0317E|test 0317E]]</td><td>29</td><td>simul.</td><td>3 tables</td><td>72%</td><td align=left></td></tr>
<tr align=center><td>[[Collab_Network_School_Mesh_Tests#Test_0323D|test 0323D]]</td><td>10</td><td>simul.</td><td>spaced, 60 cm.</td><td>60%</td><td align=left></td></tr>
<tr align=center><td>[[Collab_Network_School_Mesh_Tests#Test_0321D|test 0321D]]</td><td>38</td><td>simul.</td><td>4 tables</td><td>60%</td><td align=left></td></tr>
<tr align=center><td>[[Collab_Network_School_Mesh_Tests#Test_0323A|test 0323A]]</td><td>10</td><td>simul.</td><td>1 table</td><td>60%</td><td align=left></td></tr>
</table>


'''School Server Channels:''' 1
== School Server WiFi ==


In these [[Collab_Network_School_Wifi_Tests|tests]], the laptops are connected to the [[School server]] through normal 802.11b/g access points. In general, the laptops are registered with the school server and using the school's presence service.
This test was a staged registration of 29 laptops. 7 out of the 29 had problems finding the school mesh portal. Once they found the portal, all of the laptops registered on the first try.


=== Presence ===
Ten laptops (X50 - X59) were turned on first. They all found the school server mesh portal. They were registered, the registration verified (on the Home Screen) and Sugar restarted using CTL-ALT-ERASE.
* [[Collab_Network_School_Wifi_Tests#Test_0410A|test 0410A]], 76 laptops startup, 13 failed to associate, another 17 had problems
* [[Collab_Network_School_Wifi_Tests#Test_0410B|test 0410B]], 50 laptops startup, all associated, 8 had presence problems, others missing neighbors
* [[Collab_Network_School_Wifi_Tests#Test_0410C|test 0410C]], 50 laptops startup, 2 failed to associate, 6 had presence problems, others missing neighbors
* [[Collab_Network_School_Wifi_Tests#Test_0410D|test 0410D]], 49 laptops startup + BW hog, 5 failed to associate, 6 had presence problems
* [[Collab_Network_School_Wifi_Tests#Test_0408B|test 0408B]], 38 laptops staged startup, no problems
* [[Collab_Network_School_Wifi_Tests#Test_0408F|test 0408F]], 77 laptops startup, 6 didn't associate
* [[Collab_Network_School_Wifi_Tests#Test_0331G|test 0331G]], poor AP, 28 laptops startup, pure chaos
* [[Collab_Network_School_Wifi_Tests#Test_0323J|test 0323J]], poor AP
* [[Collab_Network_School_Wifi_Tests#Test_0323K|test 0323K]], poor AP
=== Write sharing ===
* [[Collab_Network_School_Wifi_Tests#Test_0410F|test 0410F]], 50 laptops + BW hog, 40 successfully sharing Write and Chat
* [[Collab_Network_School_Wifi_Tests#Test_0331H|test 0331H]], poor AP, 24 laptops, no collaboration
=== Read sharing ===


=== Chat ===
Another ten laptops (X61 - X70) were turned on. Four (X62, X64, X65, and X68) didn't find the school mesh portal, and joined a simple mesh on channel 1 ([http://dev.laptop.org/ticket/5963 Trac 5963]). Clicking on mesh channel 1 in the neighborhood view caused three of the laptops to find the school mesh portal, and trying twice worked on the fourth (X65).
* [[Collab_Network_School_Wifi_Tests#Test_0410E|test 0410E]], 50 laptops + BW hog, 49 successfully sharing Chat
* [[Collab_Network_School_Wifi_Tests#Test_0408C|test 0408C]], 78 laptops, 75 successfully sharing Chat


== Simple WiFi ==
Another nine laptops (X71 - X79) were turned on. Three of these didn't find the school mesh portal ([http://dev.laptop.org/ticket/5963 Trac 5963]), but all three found it on the first manual retry.


In these [[Collab_Network_Simple_Wifi_Tests|tests]], the laptops are connected to one another and the Internet, through a normal 802.11b/g access point. All presence and collaboration is Peer-to-Peer.
All of the laptop registered on the first try, but registration wasn't simultaneous.


=== Chat ===
'''Packet Traces:''' [http://xs-dev.laptop.org/mesh/test0317/t0317_D_1.dump Chan 1], [http://xs-dev.laptop.org/mesh/test0317/t0317_D_11.dump Chan 11], [http://xs-dev.laptop.org/mesh/test0317/t0317_D_6.dump Chan 6]
* [[Collab_Network_Simple_Wifi_Tests#Test_0331D|Test 0331D]], 28 laptops, 9 of 10 successful
=== Write sharing ===
* [[Collab_Network_Simple_Wifi_Tests#Test_0331E|Test 0331E]], 28 laptops, 5 of 10 successful
* [[Collab_Network_Simple_Wifi_Tests#Test_0330A|Test 0330A]], Two laptops, 2 of 2 successful
* [[Collab_Network_Simple_Wifi_Tests#Test_0330C|Test 0330C]], Three laptops, 3 of 3 successful
* [[Collab_Network_Simple_Wifi_Tests#Test_0330D|Test 0330D]], Six laptops, 6 of 6 successful
=== Measure ===
* [[Collab_Network_Simple_Wifi_Tests#Test_0330B|Test 0330B]], Two laptops, successful
===Read sharing===
* [[Collab_Network_Simple_Wifi_Tests#Test_0331F|Test 0331F]], 28 laptops, 440 KB file, 1.5 of 4 successful
* [[Collab_Network_Simple_Wifi_Tests#Test_0330E|Test 0330E]], Six laptops, 2.2 MB file, 0 of 6 successful
* [[Collab_Network_Simple_Wifi_Tests#Test_0330F|Test 0330F]], Six laptops, 40 KB file, 5 of 6 successful
* [[Collab_Network_Simple_Wifi_Tests#Test_0330G|Test 0330G]], Six laptops, 440 KB file, 6 of 6 successful
* [[Collab_Network_Simple_Wifi_Tests#Test_0330H|Test 0330H]], Six laptops, 440 KB file, 6 of 6 successful


==== Test 0317C ====
== Jabber Scaling ==


In these [[Collab_Network_Jabber_Scaling_Tests|tests]], the laptops are connected to one school server via the Internet. There is no local RF contention. This isolates the Jabber server and can be performed by many isolated individuals.
'''Laptop Build:''' 699


'''School Server Build:''' 160
=== Server health ===

'''School Server Channels:''' 1

This test was supposed to be a staged registration of laptops. It was aborted after three (X52 - X54) of the first five laptops (X50 - X54) to be turned on couldn't find a school mesh portal and instead joined a simple mesh.

The school server active antenna had been placed on the same plane as the laptops (at 1 m from the floor). The antenna was moved to about 2 m off the floor, and the test repeated as [[#Test_0317D|0317D]].

'''Packet Traces:''' [http://xs-dev.laptop.org/mesh/test0317/t0317_C_1.dump Chan 1], [http://xs-dev.laptop.org/mesh/test0317/t0317_C_11.dump Chan 11], [http://xs-dev.laptop.org/mesh/test0317/t0317_C_6.dump Chan 6]


=== Presence ===
=== Presence ===


==== Test 0317E ====
=== Chat sharing ===


=== Write sharing ===
'''Laptop Build:''' 699


=== Read sharing ===
'''School Server Build:''' 160


=== Record sharing ===
'''School Server Channels:''' 1


=== Browse sharing ===
This test was a simultaneous booting up of 29 registered laptops. 8 out of the 29 had problems finding the school mesh portal ([http://dev.laptop.org/ticket/5963 Trac 5963]). Once they found the portal, all of the laptops connected using gabble (although three had to have sugar restarted before they would display neighbors properly.)


[[Category:Collaboration]]
All 29 laptops (X50 - X59, X61 - X79) had previously been registered with the school server (and the school ejabberd server). They were turned on within a sixty second period, starting with X50 and moving up.

21 of the 29 laptops found the school server mesh portal. The ones that didn't ([http://dev.laptop.org/ticket/5963 Trac 5963]) were X57, X65, X68, X70, X72, X75, X78, and X79. Note that these were the last ones turned on!

All 8 failing laptops found the school mesh portal after clicking on mesh channel 1 in the neighborhood view.
Three of the failing laptops (X65, X68, and X75) didn't show other laptops in their neighborhood view until Sugar was restarted. They were not running salut instead of gabble (they didn't show each other), instead they didn't show any other XOs at all.

'''Packet Traces:''' [http://xs-dev.laptop.org/mesh/test0317/t0317_E_1.dump Chan 1], [http://xs-dev.laptop.org/mesh/test0317/t0317_E_11.dump Chan 11], [http://xs-dev.laptop.org/mesh/test0317/t0317_E_6.dump Chan 6]

'''Server logs:''' [http://xs-dev.laptop.org/mesh/test0317/server_log /var/log/messages], [http://xs-dev.laptop.org/mesh/test0321/school_list later output of school_who]

[[Collab_Network_Test_0317E|Discussion of Packet Traces]]

==== Test 0321D ====

'''Laptop Build:''' 699 + telepathy-salut-0.2.3-1.olpc2.i386.rpm

'''School Server Build:''' 160 + 22.p6 Libertas firmware

'''School Server Channels:''' 1

This test was a simultaneous booting up of 29 registered laptops and 9 unregistered ones. 15 out of the 38 had problems finding the school mesh portal ([http://dev.laptop.org/ticket/4153 Trac 4153], [http://dev.laptop.org/ticket/5963 5963]). Most found the mesh portal after the mesh 1 circle in the neighborhood view was clicked on, but three (X71, X92, X96) required a reboot. Once they found the portal, all of the unregistered laptops registered on the first try and all connected using gabble.

29 of the laptops (X50 - X59, X61 - X79) had previously been registered with the school server (and the school ejabberd server). They were upgraded to have telepathy-salut-0.2.3-1.olpc2.i386.rpm and all logs (libertas, telepathy, sugar) turned on. Another nine unregistered laptops (X90 - X98) were used without the upgraded telepathy-salut. Salut shouldn't be used when connected to a school server, so no difference was expected.
They were all turned on within a ninety second period, starting with X50 and moving up.

23 of the 38 laptops found the school server mesh portal. The ones that didn't ([http://dev.laptop.org/ticket/4153 Trac 4153], [http://dev.laptop.org/ticket/5963 5963]) were X53, X54, X58, '''X59''', X64, '''X71''', X73, X74, X76, X77, X79, X91, X92, X95, and X96. Note less correlation with startup time than seen in [[#Test_0317E|Test 0317E]].

Twelve of the failing laptops found the school mesh portal after clicking on mesh channel 1 in the neighborhood view. Three of the failing laptops (X71, X92, and X96) didn't find it after two clicks, but did find it immediately upon reboot.

Two of the laptops (X91 aka 00:17:C4:11:14:5D aka 172.18.10.236, and X92 aka 00:17:C4:0D:14:54 aka 172.18.11.234) entered a weird state after having Sugar rebooted to force an ejabberd registration after a registration of the laptop with the school server. Unfortunately, no logs were obtained and the problem disappeared on reboot. More details later...

'''Packet Traces:''' [http://xs-dev.laptop.org/mesh/test0321/t0321_D_1.dump Chan 1], [http://xs-dev.laptop.org/mesh/test0321/t0321_D_11.dump Chan 11], [http://xs-dev.laptop.org/mesh/test0321/t0321_D_6.dump Chan 6]

'''Laptop X59 logs:''' [http://xs-dev.laptop.org/mesh/test0321/x59logs/ All], [http://xs-dev.laptop.org/mesh/test0321/x59logs/ dmesg], [http://xs-dev.laptop.org/mesh/test0321/x59logs/messages /var/log/messages], [http://xs-dev.laptop.org/mesh/test0321/x59logs/logs/ Telepathy/Sugar]

'''Laptop X71 logs:''' [http://xs-dev.laptop.org/mesh/test0321/x59logs/ All], [http://xs-dev.laptop.org/mesh/test0321/x59logs/ dmesg], [http://xs-dev.laptop.org/mesh/test0321/x59logs/messages /var/log/messages], [http://xs-dev.laptop.org/mesh/test0321/x59logs/logs/ Telepathy/Sugar]

'''Server logs:''' [http://xs-dev.laptop.org/mesh/test0321/x71_server_log /var/log/messages], [http://xs-dev.laptop.org/mesh/test0321/school_list output of school_who]

[[Collab_Network_Test_0321D|Discussion of Packet Traces]]

== School Server WiFi ==

Latest revision as of 21:51, 3 September 2009

While the OLPC Mesh Testbed is conveniently located in the same space used by OLPC for development and business activities, it suffers from an excess of unrelated wireless traffic. In order to allow repeatable testing of larger numbers of laptops, a larger testbed has been set up at another location in the Boston area, where the 802.11b spectrum is relatively unused.

Test Setup

At this location, we currently have a hundred laptops and a school server, along with a separate packet recording machine. Ten laptops are grouped together on each 1.5 m by 0.7 m table. We hope to grow to at least a hundred and fifty laptops over time.

PeabodyAnnex.png

While we will eventually provide remote automated control of large portions of the testing, we are currently performing tests manually.

The laptop developer keying, upgrading, and application installation is done using USB keys.

  • The two rooms

    The two rooms

  • Server/Monitoring Room

    Server/Monitoring Room

  • View into Front Room

    View into Front Room

  • Active Antennas

    Active Antennas

Tests and Results

The tests are grouped according to the type of network used when they were performed: simple mesh, simple collaboration over managed WiFi, a mesh with a school server, or access points with a school server.

All packet traces are in wireshark format, and contain beacon and link layer management frames as well as IP packets. They were obtained using tcpdump -i rtapX -w filename.

More specifically, interfaces are configured to the appropriate channels at boot time via ifcfg_ethX files in /etc/sysconfig/network-scripts/ (eth1 to channel 1, eth2 to channel 11, and eth3 to channel 6). There is a script, setup_snoop, for setting up the interfaces which is run once after boot. Another, do_snoop, is used to start logging. Logging is stopped with sudo killall tcpdump

Simple Mesh

In these tests, the laptops are connected solely to one another, through the wireless mesh. All presence and collaboration is Peer-to-Peer.

Startup

Write sharing

  • test 0331A, 28 laptops, 5 of 7 succeed at joining Write
  • test 0321B, 10 laptops, 9 of 9 succeed at joining Write
  • test 0317B, 25 laptops, 7 of 10 succeed at joining Write

Read sharing

  • test 0331C, 28 laptops, 0 of 5 succeed at joining Read
  • test 0321A, 10 laptops, 0 of 2 succeed at joining Read

Chat

School Server Mesh

In these tests, a School server equipped with one to three Active Antenna provides the interconnection for the laptops. In general, the laptops are registered with the school server and using the school's presence service.

Startup & Registration

Presence

Chat

Write sharing

Read sharing

Startup Problems (#5963)

This table summarizes the tests done in search of information on Trac ticket 4153 (Trac ticket 5963 is a duplicate), an inability to reliably DHCP upon startup that impacts other use of the mesh as well. The information listed after each test is the number of laptops involved in the test, how they were started up (simultaneously or staggered in some way), and the number that successfully managed to find a school portal.

TestNum. LaptopsTimingSpacingSuccessComments
test 0323G10staged 5 sec1 table90%
test 0323H20staged 7.5 sec2 tables90%groups of 2, 15 sec apart
test 0323E15staged 10 secspaced, 20 cm87%
test 0323B10simul.spaced80%
test 0323F10simul.1 table80%
test 0317D29grouped3 tables76%3 groups of 10, 5 min. apart
test 0323C15simul.spaced, 30 cm.73%
test 0317E29simul.3 tables72%
test 0323D10simul.spaced, 60 cm.60%
test 0321D38simul.4 tables60%
test 0323A10simul.1 table60%

School Server WiFi

In these tests, the laptops are connected to the School server through normal 802.11b/g access points. In general, the laptops are registered with the school server and using the school's presence service.

Presence

  • test 0410A, 76 laptops startup, 13 failed to associate, another 17 had problems
  • test 0410B, 50 laptops startup, all associated, 8 had presence problems, others missing neighbors
  • test 0410C, 50 laptops startup, 2 failed to associate, 6 had presence problems, others missing neighbors
  • test 0410D, 49 laptops startup + BW hog, 5 failed to associate, 6 had presence problems
  • test 0408B, 38 laptops staged startup, no problems
  • test 0408F, 77 laptops startup, 6 didn't associate
  • test 0331G, poor AP, 28 laptops startup, pure chaos
  • test 0323J, poor AP
  • test 0323K, poor AP

Write sharing

  • test 0410F, 50 laptops + BW hog, 40 successfully sharing Write and Chat
  • test 0331H, poor AP, 24 laptops, no collaboration

Read sharing

Chat

  • test 0410E, 50 laptops + BW hog, 49 successfully sharing Chat
  • test 0408C, 78 laptops, 75 successfully sharing Chat

Simple WiFi

In these tests, the laptops are connected to one another and the Internet, through a normal 802.11b/g access point. All presence and collaboration is Peer-to-Peer.

Chat

Write sharing

Measure

Read sharing

  • Test 0331F, 28 laptops, 440 KB file, 1.5 of 4 successful
  • Test 0330E, Six laptops, 2.2 MB file, 0 of 6 successful
  • Test 0330F, Six laptops, 40 KB file, 5 of 6 successful
  • Test 0330G, Six laptops, 440 KB file, 6 of 6 successful
  • Test 0330H, Six laptops, 440 KB file, 6 of 6 successful

Jabber Scaling

In these tests, the laptops are connected to one school server via the Internet. There is no local RF contention. This isolates the Jabber server and can be performed by many isolated individuals.

Server health

Presence

Chat sharing

Write sharing

Read sharing

Record sharing

Browse sharing

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