Re: [B.A.T.M.A.N.] Mangling broadcast packets

[Jan Huwald <jh@sotun.de>]

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Hi Simon,

thanks for your advice.


On 07/26/2013 02:16 PM, Simon Wunderlich wrote:
> * send unicast to each neighbor instead of sending broadcast (find 
> out who is a neighbor by reading originator tables) --> using unicast
> might be faster than using broadcast too, which is usually fixed to a
> lower mcast rate.

I had not considered the mcast rate issue. Given the typical low degree
topology that is probably the most efficient way to go. Even more so
given that bcast-packets are send several times. (I just discovered this
in the batman srcs.)


> alfred, which servers a similar purpose (at least i think so) does
> the same.

We had a look at alfred, but unfortunately it is no replacement for us.
But hopefully I can copy your neighbourhood discovery code :-)


Nitpicking part:

>> * using NFQUEUE on all enslaved interfaces to mangle packets
>> before they are seen by batman; requires out-of-kernel parsing of 
>> batman-adv packets and watching enslaved interfaces
> 
> out-of-kernel parsing of batman-adv packets will kill you
> performance completely.

By filtering with U32 and friends only packets that are scheduled for
local delievery anyway would be processed in userspace. That _should_
have only a minor performance impact. (And only be ugly^10.)

With best regards,
Jan


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