Date: Thu, 19 Oct 2000 15:14:39 -0500 From: "C. Stephen Gunn" <csg@waterspout.com> To: MIHIRA Sanpei Yoshiro <sanpei@sanpei.org> Cc: freebsd-net@FreeBSD.ORG Subject: Re: [Patch] VLAN MTU1500 patch for FreeBSD 4.1-RELEASE and later Message-ID: <20001019151439.A17464@waterspout.com> In-Reply-To: <200010191411.e9JEBZ817011@lavender.sanpei.org>; from sanpei@sanpei.org on Thu, Oct 19, 2000 at 11:11:35PM %2B0900 References: <200010191411.e9JEBZ817011@lavender.sanpei.org>
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On Thu, Oct 19, 2000 at 11:11:35PM +0900, MIHIRA Sanpei Yoshiro wrote: > This is VLAN MTU1500 patch for FreeBSD 4.1-RELEASE and > later(sorry, I did not test under 5-current). This patch was created > by HOSOKAWA Tatsumi-san(hosokawa@FreeBSD.org), but he was too busy > to announce and commit. So I post this patch by proxy. > > This patch was tested: > - with Intel PRO/100+ Management Adapter(fxp) > - with Netgear Gigabit Ethernet (MM SC) GA-620 In my experience with VLAN interfaces, most of this code should not be necessary. The problem lies in the difference in the MTU used by IP, and the maximum frame size a card/driver will receive. There isn't currently a mechanism in FreeBSD to either allow the physical device to report what its maximum receive framesize is, or to allow the vlan driver to request a larger one. While inelegant, I've simply configured my ethernet cards (ti/xl) to allow larger frames to be passed to ether input. With this patch installed, you can simply: ifconfig xl0 up ifconfig vlan0 vlan 123 vlandev xl0 inet 1.2.3.4 netmask 0xffffff00 mtu 1500 You have to set the MTU on the vlan device because the the default is ETHERMTU - EVL_ENCAPLEN (1496). If your hardware _actually_ delivers the oversize frames you're fine. My patch for the xl driver (works on 3c905B-TX cards) is available online. It simply allows for larger frames. http://www.physics.purdue.edu/~csg/FreeBSD/xl_vlan.patch - Steve To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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