Date: Fri, 4 Feb 2000 17:01:10 -0800 (PST) From: Hugh LaMaster <lamaster@nren.nasa.gov> To: "FreeBSD-Net (FreeBSD.Org)" <freebsd-net@FreeBSD.ORG> Subject: Re: 802.1Q VLANs Message-ID: <Pine.GSO.4.05.10002041648430.4536-100000@kinkajou.arc.nasa.gov> In-Reply-To: <200002041605.LAA68266@khavrinen.lcs.mit.edu>
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On Fri, 4 Feb 2000, Garrett Wollman wrote: > > make sure that the NIC won't drop oversized frames so it can examine them, > > but if it sees a 1522-byte frame that doesn't belong to a 802.1Q VLAN it > > will drop that frame (as well as any frame longer than 1522 bytes). > > No, it should not. When debugging networks, all frames should be > made available (including true error frames, although that's a bit > harder). I think it may have been mentioned in one of these threads, but, I didn't see it in this one, so, I thought I should mention that even longer frames have been around for a while. Cisco provided ISL before 802.1Q was defined, and, it can have frame sizes of up to 1548 on Ethernet, according to the Cisco documentation. Since many of the Cisco FastEthernet ports are based on the DEC21140 chipset, at least the Cisco variant can handle frame sizes that large (perhaps all variants can, I don't know). The DEC21140 chipset came out about 5 years ago, IIRC. So, anyone who wants to dump ethernet frames on ISL trunks should be ready for framesize of 1548. Additions/corrections more than welcome. -- Hugh LaMaster, M/S 233-21, Email: lamaster@nren.nasa.gov NASA Ames Research Center Or: lamaster@nas.nasa.gov Moffett Field, CA 94035-1000 Or: lamaster@george.arc.nasa.gov Phone: 650/604-1056 Disc: Unofficial, personal *opinion*. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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