Re: [B.A.T.M.A.N.] ap_isolation issue

Andre Courchesne
2012-01-26T21:46:44Z

Ok, did a bit of tcpdump and my test was the following:

tcpdump running on the linux firewall on the NIC (5.0.0.1) where AP#1 is connected.

From the linux server I ping AP#1 (T004) and as expected I see:

16:37:38.013775 arp who-has 5.0.0.1 tell T004
16:37:38.013792 arp reply 5.0.0.1 is-at 00:0e:2e:bd:d7:88 (oui Unknown)
16:37:39.010099 IP 5.0.0.1 > T004: ICMP echo request, id 22020, seq 24, length 64
16:37:39.010345 IP T004 > 5.0.0.1: ICMP echo reply, id 22020, seq 24, length 64

Pinging AP#2 (T003), I only get:

16:39:05.165998 arp who-has T003 tell 5.0.0.1

But there are no arp replies.

If I disable ap_isolation on AP#1, and make sure I do not have T003 in the arp table it finally gets it but takes a bit:

[root@andre-test~]# ping T003
PING T003 (5.1.180.144) 56(84) bytes of data.
From 5.0.0.1 icmp_seq=2 Destination Host Unreachable
From 5.0.0.1 icmp_seq=3 Destination Host Unreachable
From 5.0.0.1 icmp_seq=4 Destination Host Unreachable
From 5.0.0.1 icmp_seq=6 Destination Host Unreachable
From 5.0.0.1 icmp_seq=7 Destination Host Unreachable
From 5.0.0.1 icmp_seq=8 Destination Host Unreachable
From 5.0.0.1 icmp_seq=10 Destination Host Unreachable
From 5.0.0.1 icmp_seq=11 Destination Host Unreachable
From 5.0.0.1 icmp_seq=12 Destination Host Unreachable
From 5.0.0.1 icmp_seq=15 Destination Host Unreachable
From 5.0.0.1 icmp_seq=16 Destination Host Unreachable
From 5.0.0.1 icmp_seq=19 Destination Host Unreachable
From 5.0.0.1 icmp_seq=20 Destination Host Unreachable
64 bytes from T003 (5.1.180.144): icmp_seq=23 ttl=64 time=4.84 ms
64 bytes from T003 (5.1.180.144): icmp_seq=24 ttl=64 time=2.91 ms
64 bytes from T003 (5.1.180.144): icmp_seq=25 ttl=64 time=2.53 ms
64 bytes from T003 (5.1.180.144): icmp_seq=26 ttl=64 time=1.47 ms
64 bytes from T003 (5.1.180.144): icmp_seq=27 ttl=64 time=1.50 ms
64 bytes from T003 (5.1.180.144): icmp_seq=28 ttl=64 time=1.46 ms
64 bytes from T003 (5.1.180.144): icmp_seq=29 ttl=64 time=1.47 ms

With the tcp dump traces:
16:44:38.378149 arp who-has 5.0.0.1 tell T003
16:44:38.378215 arp reply 5.0.0.1 is-at 00:0e:2e:bd:d7:88 (oui Unknown)

On 2012-01-26, at 3:45 PM, Marek Lindner wrote:

> On Friday, January 27, 2012 04:39:24 Andre Courchesne wrote:
>> Sorry for the reply on the other post, getting tired I guess...
>>
>>
>> So...
>>
>> Ok, disabling loop avoidance has no effect.
>>
>> Has ap_isolation been tested in this type of scenario?
>
> Antonio is the real expert on the AP isolation but judging your debug output
> I'd say the AP isolation has nothing to do with your problem. Also, the
> disable/enable action seems to point into the same direction.
>
> The AP isolation only drops packets from wireless clients. You should see a
> "W" in the flags section of the "batctl tg" dump:
> 02:69:fe:45:a3:cf ( 1) via ae:86:74:01:b4:94 ( 2) [...]
> Try connecting with a wireless device and you will see it. Unless we have a
> bug the traffic from the linux firewall should not be dropped (I see no W).
>
> You could get packet dumps to find out where the pings are dropped. Maybe that
> brings us closer to understanding what is going on.
>
> Regards,
> Marek