Red Hat Bugzilla – Bug 66139
MTU-Problems with VLAN
Last modified: 2007-04-18 12:42:59 EDT
From Bugzilla Helper: User-Agent: Mozilla/5.0 (compatible; Konqueror/3.0.0-10; Linux) Description of problem: NFS over VLANs: Using the standard MTU of 1500 copying large files hangs. Version-Release number of selected component (if applicable): How reproducible: Always Steps to Reproduce: 1. ifup vlan2 2. mount install:/redhad /mnt/install 3. dir /mnt/install (works perfectly) 4. cp /mnt/install/kernel.tar.gz /tmp (hangs) Actual Results: System hangs until I either shutdown the interface or reduce mtu Expected Results: file should be copied Additional info: After reducing MTU to 1400 on both sides, it works. Tested with tulip and 3C59x. Other end: RH72 without VLAN tagging connected via 3COM 3300 switch.
VLAN is known to be broken with several cards without fixes to the drivers for those cards. There is no ETA on when the fixes will be done to the cards that need them. 3c59x is one such card. The best we could do is basically make VLAN fail to initialize on such cards but that would restrict you from being able to use VLAN with a reduced MTU which does work around the problem.
rh brings vconfig package at 9 and rh-kernel has vlan support but a lot of drivers have problems with MTU/vlan. Are going this to change soon? more vlan bugs: http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=88592 http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=81570 http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=84212