Date: Fri, 12 Nov 2004 11:36:13 +0000 (GMT) From: Robert Watson <rwatson@FreeBSD.org> To: Attila Nagy <bra@fsn.hu> Cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/dev/em if_em.c if_em.h Message-ID: <Pine.NEB.3.96L.1041112113402.20686A-100000@fledge.watson.org> In-Reply-To: <41949E0C.1080602@fsn.hu>
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On Fri, 12 Nov 2004, Attila Nagy wrote: > Robert Watson wrote: > > that the card isn't doing it on transmit. Due to a feature of card > > operation, if the global VLAN prepend/strip register isn't set, > > setting the VLAN tag flag on individual packet descriptors will > > cause the packet to be transmitted using ISL encapsulation rather > > than 802.1Q VLAN encapsulation. > > AFAIK, FreeBSD has no ISL support. Would it be possible to set this > flag somehow, so the user could switch between 802.1q and ISL? This way > the NIC would do the tagging, so no kernel support would be needed I > guess. Well, I think that would immediately run into the same problem the VLAN support had: if the kernel doesn't know about the encapsulation then when the card is put in promiscuous mode, you get back the un-encapsulated packets rather than the encapsulated ones. I don't know much/anything about ISL encapsulation, but if it's similar to VLAN encapsulation it probably wouldn't be bard to implement. I identified the encapsulation type being spewed out by the if_em cards using ethereal, which does a pretty good job at identifying fairly arbitrary looking sets of bytes. :-) Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert@fledge.watson.org Principal Research Scientist, McAfee Research
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