Hello Jesse, thank you for answering anyway. Though I think your answer covers only the obvious half of the problem. Indeed one might think that this solves the issue - as long as there are only linux kernels involved. Unfortunately my setup is a bit more complicated in terms of hardware. So I should have probably clarified the question this way: how do you configure the interface in a manner that packets with data length of 1500 get transferred, and not only 1496 ? I tried enlarging both real-device and first vlan interface mtu but that does not work out. I really thought that the visible device setting of mtu=1500 should have worked out and that the driver (or some code in between) should have corrected the allowed frame size to reflect the actual setup, not?
Regards, Stephan PS: crossposted to both lists, list-members keep in mind I am not subscribed when answering! Thank you. On Mon, 28 Aug 2006 10:23:09 -0700 "Brandeburg, Jesse" <[EMAIL PROTECTED]> wrote: > Stephan von Krawczynski wrote: > > Hello Jesse, > > > > sorry to bother you directly, but since you did the patch for my e1000 > > interrupt problem last time (February) I hope you have a short-hand > > idea for my current issue, too. > > > > I am trying to make stacked vlan tagging work under kernel 2.4 with > > e1000. Generally I do this on two boxes connected back-to-back: > > > > ifconfig eth0 up > > vconfig add eth0 4094 > > ifconfig eth0.4094 up > > vconfig add eth0.4094 1 > > ifconfig eth0.4094.1 192.168.1.1 netmask 255.255.255.0 broadcast > > 192.168.1.255 up > > > > (of course the second box gets another ip, lets assume .2). > > > > if you do a > > > > ping -s 1472 192.168.1.2 > > > > through the stacked vlan you see the packets vanish. > > With > > > > ping -s 1468 192.168.1.2 > > > > everything seems ok. > > > > I have the impression that the stacked vlans show some problem with > > mtu handling inside the e1000 driver. Mtu is set to 1500 but because > > stacking tags uses 4 bytes more the packets cannot use the full mtu. > > Any ideas what happens here? > > The packet is being dropped because it is longer than the allowed frame > size for 1500 MTU. check ethtool -S eth0 > > mine shows > rx_long_length_errors: 169 > > which indicates that you need to change your mtu on the stacked > interface to 1496, at which point after I did: > > ip l s eth1.4094.1 mtu 1496 > > on both sides of my connection, everything was working. I think in this > case it is just a configuration problem. When you stack vlans you have > to account for the extra inserted length someplace and that place is by > reducing the MTU. > > I'd appreciate it in the future if you could use > [EMAIL PROTECTED] or netdev@vger.kernel.org for support questions > like this because I'm not the only one who can answer questions (and I > might have been on vacation! :-) ) > > Jesse > - 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
