[B.A.T.M.A.N.] [batman-adv] Does batman-adv works perfectly?

[B.A.T.M.A.N.] [batman-adv] Does batman-adv works perfectly?

[Xuebing Wang]

Hi community,

We have batman-adv working on OpenWRT Chaos Calmer.
- Atheros ar9331 MIPS platform + built-in ath9k WiFi
- batman-adv version 2016.1
- routing_algos = BATMAN_IV
- Wireless interface MTU = 1532, adhoc network encryption "psk2-ccmp"
- bat0 interface MTU = 1500

We have batman-adv running on 10+ sites. For each site, there are 10-20 
nodes in the mesh network.

batman-adv runs almost perfectly (*almost*). Occasionally (occurrence 
rate is low), node drops off the batman-adv / adhoc mesh.
- Sometimes, node can recover (re-joins the mesh network automatically), 
but not always.

Any suggestions? Does batman-adv works perfectly in the field (i.e. 
running for 1 year with 100+ nodes without any issues)?

What about I use one node as Master, and other nodes ping this Master 
every 10s (or 30 seconds) (to keep mesh from inactivity)? Does this help?

Thanks.
Xuebing Wang

Re: [B.A.T.M.A.N.] [batman-adv] Does batman-adv works perfectly?

[Simon Wunderlich]

[-- Attachment #1: Type: text/plain, Size: 1482 bytes --]

Hello Xuebing,

it sounds like you have WiFi driver issues. There are some effects like key 
cache corruption, deafness, and other effects known for the AR93xx series. To 
confirm, you can try to use IPv6 link local ping (ping6 fe80:...%wlan0) to your 
neighbors. If you can ping but batman can't (e.g. use batctl) it's a batman 
issue. If both pings don't get through, it's most likely a WiFi driver issue. 
In this case, a master or something doesn't help. :)

Cheers,
     Simon

On Thursday, April 6, 2017 10:32:29 AM CEST Xuebing Wang wrote:
> Hi community,
> 
> We have batman-adv working on OpenWRT Chaos Calmer.
> - Atheros ar9331 MIPS platform + built-in ath9k WiFi
> - batman-adv version 2016.1
> - routing_algos = BATMAN_IV
> - Wireless interface MTU = 1532, adhoc network encryption "psk2-ccmp"
> - bat0 interface MTU = 1500
> 
> We have batman-adv running on 10+ sites. For each site, there are 10-20
> nodes in the mesh network.
> 
> batman-adv runs almost perfectly (*almost*). Occasionally (occurrence
> rate is low), node drops off the batman-adv / adhoc mesh.
> - Sometimes, node can recover (re-joins the mesh network automatically),
> but not always.
> 
> Any suggestions? Does batman-adv works perfectly in the field (i.e.
> running for 1 year with 100+ nodes without any issues)?
> 
> What about I use one node as Master, and other nodes ping this Master
> every 10s (or 30 seconds) (to keep mesh from inactivity)? Does this help?
> 
> Thanks.
> Xuebing Wang


[-- Attachment #2: This is a digitally signed message part. --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

Re: [B.A.T.M.A.N.] [batman-adv] Does batman-adv works perfectly?

[Sven Eckelmann]

[-- Attachment #1: Type: text/plain, Size: 487 bytes --]

On Donnerstag, 6. April 2017 09:04:50 CEST Simon Wunderlich wrote:
> Hello Xuebing,
> 
> it sounds like you have WiFi driver issues. There are some effects like key 
> cache corruption, deafness, and other effects known for the AR93xx series.

Correct, completely forgot about the deaf and 0xdeadbeef issues. There were 
also two workarounds for them [1,2] from Simon.

Kind regards,
	Sven

[1] https://patchwork.kernel.org/patch/9433619/
[2] https://patchwork.kernel.org/patch/9433621/

[-- Attachment #2: This is a digitally signed message part. --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

Re: [B.A.T.M.A.N.] [batman-adv] Does batman-adv works perfectly?

[Xuebing Wang]

Hi Sven, Simon,

Thank you very much for your help. These 2 patches are not merged 
upstream? I did see a similar patch merged (as you 2 are the authors, 
you know it very well):
 > [1] https://patchwork.kernel.org/patch/9433619/
 > [2] https://patchwork.kernel.org/patch/9433621/
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a34d0a0da1abae46a5f6ebd06fb0ec484ca099d9

Thanks again.
xuebing

On 2017年04月06日 15:13, Sven Eckelmann wrote:
> On Donnerstag, 6. April 2017 09:04:50 CEST Simon Wunderlich wrote:
>> Hello Xuebing,
>>
>> it sounds like you have WiFi driver issues. There are some effects like key
>> cache corruption, deafness, and other effects known for the AR93xx series.
> Correct, completely forgot about the deaf and 0xdeadbeef issues. There were
> also two workarounds for them [1,2] from Simon.
>
> Kind regards,
> 	Sven
>
> [1] https://patchwork.kernel.org/patch/9433619/
> [2] https://patchwork.kernel.org/patch/9433621/

Re: [B.A.T.M.A.N.] [batman-adv] Does batman-adv works perfectly?

[Sven Eckelmann]

[-- Attachment #1: Type: text/plain, Size: 794 bytes --]

On Donnerstag, 6. April 2017 16:05:26 CEST Xuebing Wang wrote:
> Hi Sven, Simon,
> 
> Thank you very much for your help. These 2 patches are not merged 
> upstream? I did see a similar patch merged (as you 2 are the authors, 
> you know it very well):
>  > [1] https://patchwork.kernel.org/patch/9433619/
>  > [2] https://patchwork.kernel.org/patch/9433621/
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a34d0a0da1abae46a5f6ebd06fb0ec484ca099d9
> 

The deaf patch is not applied upstream. But yes, the deadbeef patch was 
modified by Felix and then applied upstream (the commit you've listed here).

And these patches (in patchwork) are much newer than Chaos Calmer. So I would 
not expect to see them in the Chaos Calmer mac80211 package.

Kind regards,
	Sven

[-- Attachment #2: This is a digitally signed message part. --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

Re: [B.A.T.M.A.N.] [batman-adv] Does batman-adv works perfectly?

[Simon Wunderlich]

[-- Attachment #1: Type: text/plain, Size: 1246 bytes --]

Hi Xuebing,

I didn't try the QSDK on those devices, mainly because of its poor upstream 
support/community involvement. We tried it on other devices, with "mixed" 
results.

Cheers,
      Simon

On Monday, April 17, 2017 10:19:02 PM CEST Xuebing Wang wrote:
> Hi Sven and Simon,
> 
> Thank you very much for your help. I am curious that did you try QCA-WiFi
> driver for ath9k device (like AR9331) + OpenWRT, instead of trying to
> improve ath9k driver?
> 
> QCA-WiFi driver included in QSDK:
> https://www.codeaurora.org/projects/all-active-projects/qsdk
> 
> Thanks.
> Xuebing Wang
> 
> On Thu, Apr 6, 2017 at 3:13 PM, Sven Eckelmann <sven@narfation.org> wrote:
> > On Donnerstag, 6. April 2017 09:04:50 CEST Simon Wunderlich wrote:
> > > Hello Xuebing,
> > > 
> > > it sounds like you have WiFi driver issues. There are some effects like
> > 
> > key
> > 
> > > cache corruption, deafness, and other effects known for the AR93xx
> > 
> > series.
> > 
> > Correct, completely forgot about the deaf and 0xdeadbeef issues. There
> > were
> > also two workarounds for them [1,2] from Simon.
> > 
> > Kind regards,
> > 
> >         Sven
> > 
> > [1] https://patchwork.kernel.org/patch/9433619/
> > [2] https://patchwork.kernel.org/patch/9433621/


[-- Attachment #2: This is a digitally signed message part. --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

Re: [B.A.T.M.A.N.] [batman-adv] Does batman-adv works perfectly?

[Simon Wunderlich]

[-- Attachment #1: Type: text/plain, Size: 1246 bytes --]

Hi Xuebing,

I didn't try the QSDK on those devices, mainly because of its poor upstream 
support/community involvement. We tried it on other devices, with "mixed" 
results.

Cheers,
      Simon

On Monday, April 17, 2017 10:19:02 PM CEST Xuebing Wang wrote:
> Hi Sven and Simon,
> 
> Thank you very much for your help. I am curious that did you try QCA-WiFi
> driver for ath9k device (like AR9331) + OpenWRT, instead of trying to
> improve ath9k driver?
> 
> QCA-WiFi driver included in QSDK:
> https://www.codeaurora.org/projects/all-active-projects/qsdk
> 
> Thanks.
> Xuebing Wang
> 
> On Thu, Apr 6, 2017 at 3:13 PM, Sven Eckelmann <sven@narfation.org> wrote:
> > On Donnerstag, 6. April 2017 09:04:50 CEST Simon Wunderlich wrote:
> > > Hello Xuebing,
> > > 
> > > it sounds like you have WiFi driver issues. There are some effects like
> > 
> > key
> > 
> > > cache corruption, deafness, and other effects known for the AR93xx
> > 
> > series.
> > 
> > Correct, completely forgot about the deaf and 0xdeadbeef issues. There
> > were
> > also two workarounds for them [1,2] from Simon.
> > 
> > Kind regards,
> > 
> >         Sven
> > 
> > [1] https://patchwork.kernel.org/patch/9433619/
> > [2] https://patchwork.kernel.org/patch/9433621/


[-- Attachment #2: This is a digitally signed message part. --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

Re: [B.A.T.M.A.N.] [batman-adv] Does batman-adv works perfectly?

[Xuebing Wang]

Hi Simon / Sven,

Do you know any hardware platform on which batman-adv (or batmand) work 
perfectly and field-proven? Thanks.

Xuebing Wang

On 2017年04月06日 15:04, Simon Wunderlich wrote:
> Hello Xuebing,
>
> it sounds like you have WiFi driver issues. There are some effects like key
> cache corruption, deafness, and other effects known for the AR93xx series. To
> confirm, you can try to use IPv6 link local ping (ping6 fe80:...%wlan0) to your
> neighbors. If you can ping but batman can't (e.g. use batctl) it's a batman
> issue. If both pings don't get through, it's most likely a WiFi driver issue.
> In this case, a master or something doesn't help. :)
>
> Cheers,
>       Simon
>
> On Thursday, April 6, 2017 10:32:29 AM CEST Xuebing Wang wrote:
>> Hi community,
>>
>> We have batman-adv working on OpenWRT Chaos Calmer.
>> - Atheros ar9331 MIPS platform + built-in ath9k WiFi
>> - batman-adv version 2016.1
>> - routing_algos = BATMAN_IV
>> - Wireless interface MTU = 1532, adhoc network encryption "psk2-ccmp"
>> - bat0 interface MTU = 1500
>>
>> We have batman-adv running on 10+ sites. For each site, there are 10-20
>> nodes in the mesh network.
>>
>> batman-adv runs almost perfectly (*almost*). Occasionally (occurrence
>> rate is low), node drops off the batman-adv / adhoc mesh.
>> - Sometimes, node can recover (re-joins the mesh network automatically),
>> but not always.
>>
>> Any suggestions? Does batman-adv works perfectly in the field (i.e.
>> running for 1 year with 100+ nodes without any issues)?
>>
>> What about I use one node as Master, and other nodes ping this Master
>> every 10s (or 30 seconds) (to keep mesh from inactivity)? Does this help?
>>
>> Thanks.
>> Xuebing Wang

Re: [B.A.T.M.A.N.] [batman-adv] Does batman-adv works perfectly?

[Simon Wunderlich]

[-- Attachment #1: Type: text/plain, Size: 3281 bytes --]

Hi Xuebing,

actually, ath9k is the most used hardware platform used with batman-adv, at 
least as far as I'm aware. It is used commercially as well on some hundred 
thousand devices. I would assume that it's very hard (or impossible) to find a 
"perfect" running hardware platform and drivers. On other drivers, you will 
have trouble to even get IBSS/11s mode running.

The question is, how do you handle faults - usually, there are workarounds 
applied which happen automatically like the ones we have referenced in this 
thread. They don't happen very often (i.e. less than once a day), and many of 
them can be fixed quite fast (except for the deaf problem, which may take ~30 
seconds to recover).

However, there are also some problems which happen more often in certain 
environments or on certain hardware (maybe due to bad choices in RF design 
...). There also may be problems in certain driver versions (i.e. 
regressions). And of course, there can be issues which have not yet been 
addressed.

BTW, I've just seen that you use psk2-ccmp. There is a known problem with key 
cache corruption. I'm not sure if it was already solved and merged in Chaos 
Calmer [1]. You may want to try if the problem appears without encryption.

Cheers,
      Simon

[1] https://patchwork.kernel.org/patch/9381651/

On Saturday, April 22, 2017 3:12:54 PM CEST Xuebing Wang wrote:
> Hi Simon / Sven,
> 
> Do you know any hardware platform on which batman-adv (or batmand) work
> perfectly and field-proven? Thanks.
> 
> Xuebing Wang
> 
> On 2017年04月06日 15:04, Simon Wunderlich wrote:
> > Hello Xuebing,
> > 
> > it sounds like you have WiFi driver issues. There are some effects like
> > key
> > cache corruption, deafness, and other effects known for the AR93xx series.
> > To confirm, you can try to use IPv6 link local ping (ping6
> > fe80:...%wlan0) to your neighbors. If you can ping but batman can't (e.g.
> > use batctl) it's a batman issue. If both pings don't get through, it's
> > most likely a WiFi driver issue. In this case, a master or something
> > doesn't help. :)
> > 
> > Cheers,
> > 
> >       Simon
> > 
> > On Thursday, April 6, 2017 10:32:29 AM CEST Xuebing Wang wrote:
> >> Hi community,
> >> 
> >> We have batman-adv working on OpenWRT Chaos Calmer.
> >> - Atheros ar9331 MIPS platform + built-in ath9k WiFi
> >> - batman-adv version 2016.1
> >> - routing_algos = BATMAN_IV
> >> - Wireless interface MTU = 1532, adhoc network encryption "psk2-ccmp"
> >> - bat0 interface MTU = 1500
> >> 
> >> We have batman-adv running on 10+ sites. For each site, there are 10-20
> >> nodes in the mesh network.
> >> 
> >> batman-adv runs almost perfectly (*almost*). Occasionally (occurrence
> >> rate is low), node drops off the batman-adv / adhoc mesh.
> >> - Sometimes, node can recover (re-joins the mesh network automatically),
> >> but not always.
> >> 
> >> Any suggestions? Does batman-adv works perfectly in the field (i.e.
> >> running for 1 year with 100+ nodes without any issues)?
> >> 
> >> What about I use one node as Master, and other nodes ping this Master
> >> every 10s (or 30 seconds) (to keep mesh from inactivity)? Does this help?
> >> 
> >> Thanks.
> >> Xuebing Wang


[-- Attachment #2: This is a digitally signed message part. --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

Re: [B.A.T.M.A.N.] [batman-adv] Does batman-adv works perfectly?

[Xuebing Wang]

Hi Simon,

Thank you very much. Sven pointed to me this key cache corruption 
before, but I did not take it because it is a bit complicated. I did 
take deaf and 0xdeadbeef patches. Sven, thank you.

I am doing simple change to use software encryption (int 
ath9k_modparam_nohwcrypt = 1). It seems working ok for my simple test. 
Throughput is down about 2Mbps, which is acceptable. CPU usage is now 
60% (on ar9331) for max throughput scp, it is acceptable for my application.

I will put this software encryption in field test, at least it will show 
if my issue is related to key cache corruption or not.

Thanks again.
Xuebing Wang

On 2017年04月22日 16:35, Simon Wunderlich wrote:
> Hi Xuebing,
>
> actually, ath9k is the most used hardware platform used with batman-adv, at
> least as far as I'm aware. It is used commercially as well on some hundred
> thousand devices. I would assume that it's very hard (or impossible) to find a
> "perfect" running hardware platform and drivers. On other drivers, you will
> have trouble to even get IBSS/11s mode running.
>
> The question is, how do you handle faults - usually, there are workarounds
> applied which happen automatically like the ones we have referenced in this
> thread. They don't happen very often (i.e. less than once a day), and many of
> them can be fixed quite fast (except for the deaf problem, which may take ~30
> seconds to recover).
>
> However, there are also some problems which happen more often in certain
> environments or on certain hardware (maybe due to bad choices in RF design
> ...). There also may be problems in certain driver versions (i.e.
> regressions). And of course, there can be issues which have not yet been
> addressed.
>
> BTW, I've just seen that you use psk2-ccmp. There is a known problem with key
> cache corruption. I'm not sure if it was already solved and merged in Chaos
> Calmer [1]. You may want to try if the problem appears without encryption.
>
> Cheers,
>        Simon
>
> [1] https://patchwork.kernel.org/patch/9381651/
>
> On Saturday, April 22, 2017 3:12:54 PM CEST Xuebing Wang wrote:
>> Hi Simon / Sven,
>>
>> Do you know any hardware platform on which batman-adv (or batmand) work
>> perfectly and field-proven? Thanks.
>>
>> Xuebing Wang
>>
>> On 2017年04月06日 15:04, Simon Wunderlich wrote:
>>> Hello Xuebing,
>>>
>>> it sounds like you have WiFi driver issues. There are some effects like
>>> key
>>> cache corruption, deafness, and other effects known for the AR93xx series.
>>> To confirm, you can try to use IPv6 link local ping (ping6
>>> fe80:...%wlan0) to your neighbors. If you can ping but batman can't (e.g.
>>> use batctl) it's a batman issue. If both pings don't get through, it's
>>> most likely a WiFi driver issue. In this case, a master or something
>>> doesn't help. :)
>>>
>>> Cheers,
>>>
>>>        Simon
>>>
>>> On Thursday, April 6, 2017 10:32:29 AM CEST Xuebing Wang wrote:
>>>> Hi community,
>>>>
>>>> We have batman-adv working on OpenWRT Chaos Calmer.
>>>> - Atheros ar9331 MIPS platform + built-in ath9k WiFi
>>>> - batman-adv version 2016.1
>>>> - routing_algos = BATMAN_IV
>>>> - Wireless interface MTU = 1532, adhoc network encryption "psk2-ccmp"
>>>> - bat0 interface MTU = 1500
>>>>
>>>> We have batman-adv running on 10+ sites. For each site, there are 10-20
>>>> nodes in the mesh network.
>>>>
>>>> batman-adv runs almost perfectly (*almost*). Occasionally (occurrence
>>>> rate is low), node drops off the batman-adv / adhoc mesh.
>>>> - Sometimes, node can recover (re-joins the mesh network automatically),
>>>> but not always.
>>>>
>>>> Any suggestions? Does batman-adv works perfectly in the field (i.e.
>>>> running for 1 year with 100+ nodes without any issues)?
>>>>
>>>> What about I use one node as Master, and other nodes ping this Master
>>>> every 10s (or 30 seconds) (to keep mesh from inactivity)? Does this help?
>>>>
>>>> Thanks.
>>>> Xuebing Wang

Re: [B.A.T.M.A.N.] [batman-adv] Does batman-adv works perfectly?

[Xuebing Wang]

Hi Simon,

=> It is used commercially as well on some hundred thousand devices.

Are you saying that batman-adv has hundred of thousands (100,000+) nodes 
installed? Thanks for your always help.

Xuebing Wang

On 2017年04月22日 16:35, Simon Wunderlich wrote:
> Hi Xuebing,
>
> actually, ath9k is the most used hardware platform used with batman-adv, at
> least as far as I'm aware. It is used commercially as well on some hundred
> thousand devices. I would assume that it's very hard (or impossible) to find a
> "perfect" running hardware platform and drivers. On other drivers, you will
> have trouble to even get IBSS/11s mode running.
>
> The question is, how do you handle faults - usually, there are workarounds
> applied which happen automatically like the ones we have referenced in this
> thread. They don't happen very often (i.e. less than once a day), and many of
> them can be fixed quite fast (except for the deaf problem, which may take ~30
> seconds to recover).
>
> However, there are also some problems which happen more often in certain
> environments or on certain hardware (maybe due to bad choices in RF design
> ...). There also may be problems in certain driver versions (i.e.
> regressions). And of course, there can be issues which have not yet been
> addressed.
>
> BTW, I've just seen that you use psk2-ccmp. There is a known problem with key
> cache corruption. I'm not sure if it was already solved and merged in Chaos
> Calmer [1]. You may want to try if the problem appears without encryption.
>
> Cheers,
>        Simon
>
> [1] https://patchwork.kernel.org/patch/9381651/
>
> On Saturday, April 22, 2017 3:12:54 PM CEST Xuebing Wang wrote:
>> Hi Simon / Sven,
>>
>> Do you know any hardware platform on which batman-adv (or batmand) work
>> perfectly and field-proven? Thanks.
>>
>> Xuebing Wang
>>
>> On 2017年04月06日 15:04, Simon Wunderlich wrote:
>>> Hello Xuebing,
>>>
>>> it sounds like you have WiFi driver issues. There are some effects like
>>> key
>>> cache corruption, deafness, and other effects known for the AR93xx series.
>>> To confirm, you can try to use IPv6 link local ping (ping6
>>> fe80:...%wlan0) to your neighbors. If you can ping but batman can't (e.g.
>>> use batctl) it's a batman issue. If both pings don't get through, it's
>>> most likely a WiFi driver issue. In this case, a master or something
>>> doesn't help. :)
>>>
>>> Cheers,
>>>
>>>        Simon
>>>
>>> On Thursday, April 6, 2017 10:32:29 AM CEST Xuebing Wang wrote:
>>>> Hi community,
>>>>
>>>> We have batman-adv working on OpenWRT Chaos Calmer.
>>>> - Atheros ar9331 MIPS platform + built-in ath9k WiFi
>>>> - batman-adv version 2016.1
>>>> - routing_algos = BATMAN_IV
>>>> - Wireless interface MTU = 1532, adhoc network encryption "psk2-ccmp"
>>>> - bat0 interface MTU = 1500
>>>>
>>>> We have batman-adv running on 10+ sites. For each site, there are 10-20
>>>> nodes in the mesh network.
>>>>
>>>> batman-adv runs almost perfectly (*almost*). Occasionally (occurrence
>>>> rate is low), node drops off the batman-adv / adhoc mesh.
>>>> - Sometimes, node can recover (re-joins the mesh network automatically),
>>>> but not always.
>>>>
>>>> Any suggestions? Does batman-adv works perfectly in the field (i.e.
>>>> running for 1 year with 100+ nodes without any issues)?
>>>>
>>>> What about I use one node as Master, and other nodes ping this Master
>>>> every 10s (or 30 seconds) (to keep mesh from inactivity)? Does this help?
>>>>
>>>> Thanks.
>>>> Xuebing Wang

Re: [B.A.T.M.A.N.] [batman-adv] Does batman-adv works perfectly?

[Simon Wunderlich]

[-- Attachment #1: Type: text/plain, Size: 554 bytes --]

Hi Xuebing, On Wednesday, April 26, 2017 10:49:37 AM CEST Xuebing Wang wrote:
> Hi Simon,
> 
> => It is used commercially as well on some hundred thousand devices.
> 
> Are you saying that batman-adv has hundred of thousands (100,000+) nodes
> installed? Thanks for your always help.

Yes, installed and actively in use. The devices having batman-adv installed 
are probably some millions, since many Linux PC distributions ship the module 
along with their Linux kernel. On Debian for example, batman-adv is just an 
insmod away. ;)

Cheers,
     Simon

[-- Attachment #2: This is a digitally signed message part. --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

Re: [B.A.T.M.A.N.] [batman-adv] Does batman-adv works perfectly?

[Sven Eckelmann]

[-- Attachment #1: Type: text/plain, Size: 2080 bytes --]

On Donnerstag, 6. April 2017 10:32:29 CEST Xuebing Wang wrote:
> Hi community,
> 
> We have batman-adv working on OpenWRT Chaos Calmer.
> - Atheros ar9331 MIPS platform + built-in ath9k WiFi
> - batman-adv version 2016.1

Please update your batman-adv version. This one is known to have problems
which can cause crashes or memory corruptions.

If you are using the Chaos Calmer packages version 2016.1-3 then you should 
already have some of the fixes (I think all fixes up to 2016.3 or so). But no 
one is updating the Chaos Calmer branch in the openwrt-routing packages feed 
anymore. And I doubt that anyone will do that now because LEDE 17.01 was 
released a while ago.

[...]
> - Wireless interface MTU = 1532, adhoc network encryption "psk2-ccmp"
[..]
> We have batman-adv running on 10+ sites. For each site, there are 10-20 
> nodes in the mesh network.
> 
> batman-adv runs almost perfectly (*almost*). Occasionally (occurrence 
> rate is low), node drops off the batman-adv / adhoc mesh.
> - Sometimes, node can recover (re-joins the mesh network automatically), 
> but not always.

This sounds like problems in the wifi stack/hw. batman-adv is not handling 
adhoc or encryption - it is simply using the links which are provided by your 
wifi stack/hardware.

Your description therefore looks more like you should fix your wifi. I don't 
know why you have low rates but the IBSS problems with enabled encryption 
could be caused by an HW issue. You should check out a workaround to refresh 
the HW key cache [1] when incoming packets cannot be decrypted anymore.

> Any suggestions? Does batman-adv works perfectly in the field (i.e. 
> running for 1 year with 100+ nodes without any issues)?

There are a lot of other components which will fail during that time. For 
example your wifi stack

> What about I use one node as Master, and other nodes ping this Master 
> every 10s (or 30 seconds) (to keep mesh from inactivity)? Does this help?

I have absolutely no idea against what this should help.

Kind regards,
	Sven

[1] https://patchwork.kernel.org/patch/9381651/

[-- Attachment #2: This is a digitally signed message part. --]
[-- Type: application/pgp-signature, Size: 833 bytes --]