Re: [B.A.T.M.A.N.] [PATCH] batman-adv: Use safer default config for optional features

From: Marek Lindner <mareklindner@neomailbox.ch>
To: b.a.t.m.a.n@lists.open-mesh.org
Cc: Sven Eckelmann <sven@narfation.org>
Subject: Re: [B.A.T.M.A.N.] [PATCH] batman-adv: Use safer default config for optional features
Date: Wed, 18 Feb 2015 15:33:48 +0800	[thread overview]
Message-ID: <3583975.lz5Xt4SSRR@voltaire> (raw)
In-Reply-To: <1423153373-17033-1-git-send-email-sven@narfation.org>

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On Thursday, February 05, 2015 17:22:53 Sven Eckelmann wrote:
> The current default settings for optional features in batman-adv seems to be
> based around the idea that the user only compiles what he requires. They
> will automatically enabled when they are compiled in. For example the
> network coding part of batman-adv is by default disabled in the out-of-tree
> module but will be enabled when the code is compiled during the module
> build.
> 
> But distributions like Debian just enable all features of the batman-adv
> kernel module and hope that more experimental features or features with
> possible negative effects have to be enabled using some runtime
> configuration interface.

Interesting point. Based on what you are saying we definitely should review our 
policy and agree on sane defaults.

> The network_coding feature can help in specific setups but also has
> drawbacks and is not disabled by default in the out-of-tree module.
> Disabling by default in the runtime config seems to be also quite sane.

This feature requires the wifi driver to support promisc mode. We should keep 
it disabled.

> The distributed_arp_table is in theory a good solution to reduce connection
> problems in large networks caused by ARP packet loss. Unfortunatelly, it
> seems to also break ARP resolution in simple mesh setups. The only solution
> which seems to be used by AP firmwares seems to be the deactivation of this
> feature. Disabling this feature by default until the problem was understood
> and fixed may help new deployments to create a working mesh. Tuning of the
> mesh can still be done by them in case DAT works in their setup.

I vote for keeping DAT enabled. 

> The bridge_loop_avoidance is the only feature which is disabled by default
> but may be necessary even in simple setups. Packet loops may even be
> created during the initial node setup when this is not enabled. This is
> different than STP on bridges because mesh is usually used on Adhoc WiFi.
> Having two nodes (by accident) in the same LAN segment and in the same mesh
> network is rather common in this situation.

Agreed.

Cheers,
Marek

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