Date: Fri, 27 Jul 2001 15:57:45 +0400 From: Yar Tikhiy <yar@FreeBSD.ORG> To: Peter Jeremy <peter.jeremy@alcatel.com.au> Cc: audit@FreeBSD.ORG Subject: Re: vlan(4) manpage Message-ID: <20010727155744.E14779@comp.chem.msu.su> In-Reply-To: <20010726082642.U506@gsmx07.alcatel.com.au>; from peter.jeremy@alcatel.com.au on Thu, Jul 26, 2001 at 08:26:42AM %2B1000 References: <20010725072042.A24573@comp.chem.msu.su> <20010725191744.A77305@comp.chem.msu.su> <20010726082642.U506@gsmx07.alcatel.com.au>
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On Thu, Jul 26, 2001 at 08:26:42AM +1000, Peter Jeremy wrote: > > According to Donald Becker <becker@scyld.com>, only the later 21143 > chip versions, the 21143-TD, support VLAN. Anyway, there is no direct support for VLAN in de(4) right now. > It's possible that the > BIG_PACKET code handles long packets via a back-door approach that > works on (some?) older chips. Yes, according to if_de.c, the hack works on the 21140, 21140A, and 21041 chips. It's reflected in the vlan(4) page now. The rest of your comments weren't in vain, too. Thank you. To everybody: Here's the latest revision. If no more serious errors found, I'll commit it tomorrow. Sorry for spoiling the list with such a long audit of a single manpage, but you see, it is being written way too late and depends on poorly documented features of quite a few other drivers. And people out there seem to need it badly nowadays. -- Yar .\" .\" $FreeBSD$ .\" .Dd July 25, 2001 .Dt VLAN 4 .Os .Sh NAME .Nm vlan .Nd IEEE 802.1Q VLAN network interface .Sh SYNOPSIS .\" In -stable: .Cd pseudo-device vlan Op Ar count .Cd device vlan Op Ar count .\" .Sh DESCRIPTION The .Nm driver demultiplexes frames tagged according to the IEEE 802.1Q standard into logical .Nm network interfaces, which allows routing/bridging between multiple VLANs through a single switch trunk port. .Pp To function, a .Nm interface must be assigned a parent interface and numeric VLAN tag using .Xr ifconfig 8 . A single parent can be assigned to multiple .Nm interfaces provided they have different tags. The parent interface is likely to be an ethernet card connected to a properly configured switch port. The VLAN tag should match one of those set up in the switched network. .Pp The .Nm driver supports physical devices that do the VLAN demultiplexing in firmware. The .Ar link0 flag should be set on a .Nm interface .Pq Em not on its parent using .Xr ifconfig 8 in that case to indicate that the hardware support for the 802.1Q VLANs is present in its parent. .\" .Ss "Selecting the right network interface card to run VLANs through" By now, the only NICs that have both hardware support and proper driver hooks for the 802.1Q VLAN technology in .Fx are .Xr nge 4 , .Xr ti 4 , and .\" not in -stable .Xr txp 4 . .Pp The rest of ethernet NICs supported by .Fx can run VLANs using the software emulation in the .Nm driver. However, most of them lack the capability of transmitting and/or receiving oversized frames. Using such a NIC as a parent interface for a .Nm implies a reduced MTU on the corresponding .Nm interfaces. In the modern Internet, the latter is likely to cause .Xr tcp 4 connectivity problems due to massive, inadequate .Xr icmp 4 filtering that breaks the Path MTU Discovery mechanism. .Pp The NICs that support oversized frames are as follows: .Bl -tag -width "fxp(4)" -compact -offset indent .It Xr de 4 requires defining .Dv BIG_PACKET in the .Pa /usr/src/sys/pci/if_de.c source file and rebuilding the kernel .\" not in -stable or module. The hack works only for the 21041, 21140, and 21140A chips. .It Xr fxp 4 supports long frames for the .Nm natively. .It Xr tl 4 does support long frames. .It Xr tx 4 may begin supporting long frames soon. .It Xr xl 4 supports long frames only if the card is built on a newer chip .Pq Cyclone and above . .El Note: All of the above cards' drivers except .Xr fxp 4 don't indicate yet they support long frames. Just fix the MTU of a .Nm interface if it appears to be lower that 1500 bytes after attaching the .Nm to an above parent. .Sh SEE ALSO .Xr ifconfig 8 .Sh BUGS No 802.1Q features except VLAN tagging are implemented. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-audit" in the body of the message
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