2007/11/13, Willy Tarreau <[EMAIL PROTECTED]>: > On Mon, Nov 12, 2007 at 02:57:16PM -0800, David Miller wrote: > > From: "Chris Friesen" <[EMAIL PROTECTED]> > > Date: Mon, 12 Nov 2007 16:43:24 -0600 > > > > > David Miller wrote: > > > > > > > When you select VLAN, you by definition are asking for non-VLAN > > > > traffic to be elided. It is like plugging the ethernet cable > > > > into one switch or another. > > > > > > For max functionality it seems like the raw eth device should show > > > everything on the wire in promiscuous mode. > > > > > > If we want to sniff only the traffic for a specific vlan, we can sniff > > > the vlan device. > > > > VLAN settings are a filter of sorts, much like plugging into > > one switch or another filters traffic physically. > > > > If you don't want that filter, turn the VLAN settings off. > > I don't really agree with that view. Having spent a lot of time with > tcpdump on production systems, I can say that sometimes you'd like to > be aware that one of your VLANs is wrong and you'd simply like to > sniff the wire to guess the correct tag. And on production, you simply > cannot remove other VLANs, otherwise you disrupt the service. >
I agree. If I had a mis-plugged cable, I can guess it with tcpdump. Because I cannot see the packets. It means no such packets on the wire 100%. But if I had a incorrect vlan configuration, it's hard to sure. In a case both of mis-plugged and mis-configured situation, I cannot see anything. Moreover, if I am configuring a machine via vlan interface which is mis-configured partially, I cannot disable vlan hw acceleration feature. Thanks. Joonwoo - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
