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* Re: bat0 not capable of MTU > 1500
       [not found] <Q1WvDb-RVDm4Z2qmDwD2hpBjITfuDQMFtWJYgRrhbad0oE0M76pzK6dfZyGkClGkkJskqjMAB0ZQUpZJ250oUB_EEZaVPqQd2pDEEKknXRM=@proton.me>
@ 2023-12-12 19:30 ` Rich Chase
  2023-12-12 19:53   ` Sven Eckelmann
  0 siblings, 1 reply; 3+ messages in thread
From: Rich Chase @ 2023-12-12 19:30 UTC (permalink / raw)
  To: b.a.t.m.a.n

I am trying to create an unimpeded path MTU of 1500 on my OpenWRT router (Belkin RT-3200). I built the firmware from git Master, with kernel version 6.1, and batman-adv version 2023.2.
I have a batmesh hard-if device mastering an 802.1S mesh, which are both set to MTU=2304.

Using Luci (OpenWRT web gui for uci), I set the MTU of bat0 to 1504 to accommodate .1q vlans on bat0 -- bat0.5, bat0.110, etc.

I see in the system log:

    kern.err kernel: [751585.375855] bat0: mtu greater than device maximum


Also, if I do:

    #> ip link set bat0 mtu 1504


I get:

    ip: SIOCSIFMTU: Invalid argument


and if I test:

    #> ip link show bat0

...it says that my mtu is 1500 still.

For my life I can't see anything I'm doing wrong. Why can't bat0
have MTU greater than 1500?

I don't have any other devices mastered by bat0, other than my .1s wifi mesh link.

Throwing myself at your mercy. Help?

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: bat0 not capable of MTU > 1500
  2023-12-12 19:30 ` bat0 not capable of MTU > 1500 Rich Chase
@ 2023-12-12 19:53   ` Sven Eckelmann
  2023-12-14  2:01     ` rchase47
  0 siblings, 1 reply; 3+ messages in thread
From: Sven Eckelmann @ 2023-12-12 19:53 UTC (permalink / raw)
  To: b.a.t.m.a.n; +Cc: Rich Chase

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On Tuesday, 12 December 2023 20:30:24 CET Rich Chase wrote:
> For my life I can't see anything I'm doing wrong. Why can't bat0
> have MTU greater than 1500?
> 
> I don't have any other devices mastered by bat0, other than my .1s wifi mesh link.
> 
> Throwing myself at your mercy. Help?

https://lore.kernel.org/all/20230727-jumbo-mtu-v1-3-036ce1a6e33c@narfation.org/
https://www.open-mesh.org/issues/365

Kind regards,
	Sven

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^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: bat0 not capable of MTU > 1500
  2023-12-12 19:53   ` Sven Eckelmann
@ 2023-12-14  2:01     ` rchase47
  0 siblings, 0 replies; 3+ messages in thread
From: rchase47 @ 2023-12-14  2:01 UTC (permalink / raw)
  To: b.a.t.m.a.n

Sven,

Amazing. I applied your patch (applied cleanly to 2023.3), recompiled my firmware (I had to modify the package to use 2023.3, and to exclude outdated patches -- your jumbo-frames patch is the only one I applied), and so far it's working great I can see that bat0 is able to take an MTU of 1504, which is what I wanted. 

I didn't try to violate the MTU "space" by reducing my hard-if MTU, and I don't use NC or the other suspect cases you suggested needed testing, but I'm willing to give back and try some additional configurations, if you can give me a list of test cases (and what you want to see).

Thank you so much for maintaining this project, and for your prompt and helpful reply. I'd love to help close this issue, as it looks to me like you likely have created a good patch. I naively don't see any likely reasons why it won't always work. The logic seems right to me.

Respectfully,
Rich

^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2023-12-14  2:02 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2023-12-12 19:30 ` bat0 not capable of MTU > 1500 Rich Chase
2023-12-12 19:53   ` Sven Eckelmann
2023-12-14  2:01     ` rchase47

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