Collab Network Test 0317E

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This is a forum for discussion about the packet traces obtained in test 0317E.

Packet Traces: Chan 1, Chan 11, Chan 6

Channel 1

Following one laptop: 00:17:c4:11:08:04 (a.k.a. 172.18.11.252)

  • At 234.590, the laptop broadcasts a DHCP DISC request
  • At 234.592, it receives a DHCP reply for 172.18.11.252
  • At 234.88, the laptop multicasts an IGMP membership report
  • At 234.974, the laptop multicasts to mDNS a packet with three queries. Unfortunately, the packet dump truncates the packet right before the interesting bits...
  • At 235.07, the laptop multicasts another mDNS query, and again at 235.11, 235.365, 235.62, 235.82, etc.
  • At 236.952, the laptop queries the school DNS server
  • At 237.14, the laptop establishes a TCP connection with the school ejabberd, which continues to be the main source of this laptop's traffic for the rest of the trace.
  • At 237.25, the laptop makes another DNS request (conference.schoolserver ?)
  • At 237.41, the laptop checks in with NTP
  • At 462.14, the laptop renews its DHCP lease

Unused Channels

The unused channels (6 and 11) don't have a school server mesh portal point in this test, so they provide a picture of a laptop searching unsuccessfully for a school server.

Taking channel 6, and applying a filter: 

wlan.sa == 00:17:c4:11:81:5a

The following behavior is seen on this laptop:

  • We see Beacons sent out at irregular intervals (around 2 - 5 sec)
  • At time 66.85, we see a request for IPv6 RADV (actually two, sent with two different BSS IDs), sent at 2 Mb/s. These continue to appear at roughly every 0.25 sec.
  • At time 67.47, we see the RREQ go out for the first DHCP request. It is sent at four different rates.
  • At 68.615, a RREQ message is relayed for laptop 00:17:c4:0d:37:f5, again at 69.68, 72.69, ...
  • At 68.71 an RREQ for the DHCP server anycast MAC is resent
  • At 71.72, an RREQ for the DHCP server is resent
  • At 72.25, an RREQ is relayed for laptop 00:17:c4:0d:00:01, again at 73.27, ...
  • At 72.54, an RREQ is relayed for laptop 00:17:c4:11:01:f0, again at 74.54, ...
  • At 75.72, an RREQ for the DHCP server is resent
  • Numerous RREQs for other laptops are relayed
  • At 82.72, an RREQ for the DHCP server is resent
  • At 134.61, we see an omen of future problems, as an ARP request from the school server (transmitted on channel 1!) is relayed.
  • Again at 135.99, we see another channel 1 relay, an RREQ from the school server.
  • At 158 sec, we leave this channel for the next one.
  • Overall, roughly 90 seconds were spent on this channel!

For a closer look at "bleed through" from channel 1, try this filter: 

wlan.sa == 00:50:43:28:26:2d || wlan.da == 00:50:43:28:26:2d
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