Hi, On Fri, Jun 29, 2007 at 05:19:06PM +0100, Gary Smith wrote: > I have been running a VLAN configured system for some years using 10/100 > Sundance driver cards without a problem. I recently tried on a HP > proliant server using gigabit cards and found a problem related to the > MTU size for the interface I an using. > > The 10/100 cards seem to need a MTU of 1504 bytes, but this size does > not work with the e1000 gig cards, or the US robotics, Dlink DGE, > broadcom etc. I have to move the MTU down to 1500 to make fragmentation > work and allow it to pass the larger packets. >From what I read, I guesss the vlan on sundance is software only, and need a special MTU of 1504. Most gigabit cards (not all!) already strip the vlan tag, so the driver only sees a payload of 1500 and somewhere else in the receiver buffer the vlan tag is found. > Is this what I should expect from the e1000, broadcom, R8169 drivers for > gigabit cards? I've been using vlans since 2.4.14 or so, and I have never had to set the MTU size to 1504 for any of my cards. I do know however that some of the drivers need the MTU size of 1504 to keep it from discarding it as a long packet and to cope for the increased buffer size needed. _______________________________________________ Vlan mailing list Vlan@xxxxxxxxxxxxxxx http://www.candelatech.com/mailman/listinfo/vlan
