Date: Sun, 23 Jan 2005 12:22:19 +0100 From: Jeremie Le Hen <jeremie@le-hen.org> To: Brooks Davis <brooks@one-eyed-alien.net> Cc: Jeremie Le Hen <jeremie@le-hen.org> Subject: Re: [PATCH] 802.1p priority (fixed) Message-ID: <20050123112219.GJ36660@obiwan.tataz.chchile.org> In-Reply-To: <20050122203347.GB4466@odin.ac.hmc.edu> References: <41F1E99A.5070001@ntmk.ru> <20050122152546.GG36660@obiwan.tataz.chchile.org> <20050122203347.GB4466@odin.ac.hmc.edu>
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> > Having the possibility to test and set the 802.1p or TOS values > > separately would avoid making a "trust"/"override" subtlety and will > > obviously make it more flexible. > > I agree on this point. The one thing to be careful of is that 802.1p > priorities and TOS values work rather differently in that TOS values fit > in to an existing field of the packet and 802.1p values require > modifications to the header and adding data between the header and the > real body, possiably with a resuling reduction in MTU (though what > you're doing trying to use 802.1p priority with crappy nic I don't know > :-). I do not understand your point here. TOS is indeed an existing field of the IPv4 header but AFAIK, this is the same for the 802.1p header [1]. There are already 3 bits reserved for priority (802.1p) near the 802.1q field which are both inside what they call "Tag Control Information". Regards, [1] http://www.networkdictionnary.com/protocols/8021p.php -- Jeremie Le Hen jeremie@le-hen.org
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