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Date: Tue, 11 Dec 2012 23:34:35 +0100
From: Simon Wunderlich <simon.wunderlich@s2003.tu-chemnitz.de>
Message-ID: <20121211223435.GA17765@pandem0nium>
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Subject: Re: [B.A.T.M.A.N.] [RFC] batman-adv: postpone OGM preparation to
 sending time
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On Tue, Dec 11, 2012 at 10:57:24PM +0100, Antonio Quartulli wrote:
> OGMs are currently prepared 1 originator interval in advance then the tim=
e they
> are used to be sent. This means that once in the air they carry old infor=
mation
> (e.g. TT announcements).
>=20
> To fix this, postpone the OGM creation to the same time of sending, in th=
is way
> the OGM is first created and then immediately sent.
>=20
> This patch also removes an insane "-2" that was introduced with
> 4d30670880c84071dba4b220f595e64d6c01d1ba ("batman-adv: accept delayed
> rebroadcasts to avoid bogus routing under heavy load") in the OGM seqno
> validation code that was put there to fix a possible heavy loaded scenari=
o.
> First that operation shown to be completely not valid and consequently it=
 was
> creating problem to the new behaviour introduced by this patch

Actually the -2 was not introduced there but was present (in some form) for=
 a much
longer time ... something before 2009, didn't trace it to the very end. :)

The reason for this was:
 * seqno is increased right after scheduling a new (own OGM)
 * the scheduled OGM was waiting one more cycle before beeing finally sent

Seems we forgot to document this properly, but removing this one is a good =
idea. :)
Your patch thankfully seems to correctly eliminate both reasons for "correc=
ting" the
incoming seqno.

I haven't reviewed the rest (don't know if this will stir trouble for the a=
ggregation),
but wanted to comment on this history bit. :) Please remove/correct the ref=
erence if
you merge or send it again.

Thanks!
	Simon

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