#4131 BLOC First D: WLAN appears to die after some number of suspend/resumes
Zarro Boogs per Child
bugtracker at laptop.org
Wed Oct 17 15:42:41 EDT 2007
#4131: WLAN appears to die after some number of suspend/resumes
-----------------------+----------------------------------------------------
Reporter: wad | Owner: jcardona
Type: defect | Status: assigned
Priority: blocker | Milestone: First Deployment, V1.0
Component: wireless | Version:
Resolution: | Keywords: mesh
Verified: 0 |
-----------------------+----------------------------------------------------
Changes (by jcardona):
* owner: rchokshi => jcardona
* status: new => assigned
Comment:
The following was observed on one of the devices under test that failed:
1. dut does not wake up via wireless.
2. dut does wake up via power button.
3. while dut awake it cannot ping other nodes in infrastructure.
4. sniffer reveals that ARP packets are being transmitted, but no
response is received.
5. after populating the arp table manually ICMP echo requests starts
being transmitted ({{{dut MAC: 00:17:c4:05:2d:fa}}})
{{{
sniff at sniff:~$ sudo tcpdump -i ath1 -s 1500 -e | grep -i
SA:00:17:c4:05:2d:fa
15:35:38.328464 DA:00:13:10:7d:b5:fb (oui Unknown) SA:00:17:c4:05:2d:fa
(oui Unknown) BSSID:02:2f:af:93:ef:6b (oui Unknown) LLC, dsap SNAP (0xaa),
ssap SNAP (0xaa), cmd 0x03: oui Ethernet (0x000000), ethertype IPv4
(0x0800): 192.168.5.62 > 192.168.5.2: ICMP echo request, id 19724, seq
514, length 64
}}}
6. sniffer reveals no reply is transmitted to the dut:
{{{
sniff at sniff:~$ sudo tcpdump -i ath1 -s 1500 -e | grep -i
RA:00:17:c4:05:2d:fa
15:37:23.590191 RA:00:17:c4:05:2d:fa (oui Unknown) Acknowledgment
<only 802.11 acknowledgments>
}}}
7. sniffer reveals that AP (b5:fb), instead sending data to dut, is
sending it to another AP (b5:fd). Lazy-WDS can cause routing loops, and
this appears to be what we see here:
{{{
sniff at sniff:~$ sudo tcpdump -i ath1 -s 1500 -e | grep -i
DA:00:17:c4:05:2d:fa
15:29:50.253762 RA:00:17:c4:05:2c:e3 (oui Unknown) TA:00:13:10:7d:b5:fd
(oui Unknown) DA:00:17:c4:05:2d:fa (oui Unknown) SA:00:13:10:7d:b5:fb (oui
Unknown) LLC, dsap Unknown (0x10), ssap Unknown (0xfa), cmd 0xaaaa:
Information, send seq 85, rcv seq 85, Flags [Command, Poll], length 94
}}}
This is certainly one problem. If this is the '''only''' problem causing
the symptoms described in this ticket, pinging over the mesh should work
(the description of the ticket says it does not).
Can someone verify?
'''Suggestion:''' Can't we blacklist this AP? Or provide a firmware
image for it (this model's firmware can be replaced by
[http://openwrt.org/ OpenWRT]) with Lazy-WDS disabled? The Lazy-WDS
"feature" on the WRT54G is not based on any standard, not documented and
has well known weaknesses.
--
Ticket URL: <https://dev.laptop.org/ticket/4131#comment:7>
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