Your message dated Tue, 24 Feb 2009 23:19:58 +0100
with message-id <[email protected]>
and subject line Re: vlan: vconfig should adjust MTU of created device
has caused the Debian Bug report #505998,
regarding vlan: vconfig should adjust MTU of created device
to be marked as done.
This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.
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--
505998: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=505998
Debian Bug Tracking System
Contact [email protected] with problems
--- Begin Message ---
Package: vlan
Version: 1.9-3
Severity: normal
When adding a vlan to eth0, for example:
vconfig add eth0 2
The MTU of the new device is not changed.
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP
qlen 1000
3: eth...@eth0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN
Surely this ought to be
3: eth...@eth0: <BROADCAST,MULTICAST> mtu 1492 qdisc noop state DOWN
-- System Information:
Debian Release: lenny/sid
APT prefers testing
APT policy: (990, 'testing'), (500, 'unstable')
Architecture: amd64 (x86_64)
Kernel: Linux 2.6.26-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash
Versions of packages vlan depends on:
ii iproute 20080725-2 networking and traffic control too
ii libc6 2.7-15 GNU C Library: Shared libraries
vlan recommends no packages.
vlan suggests no packages.
-- no debconf information
--- End Message ---
--- Begin Message ---
Hi Paul,
> When adding a vlan to eth0, for example:
>
> vconfig add eth0 2
>
> The MTU of the new device is not changed.
>
> 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state
> UP qlen 1000
> 3: eth...@eth0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN
>
> Surely this ought to be
>
> 3: eth...@eth0: <BROADCAST,MULTICAST> mtu 1492 qdisc noop state DOWN
No, 1492 is definitely wrong because:
* a VLAN tag is only 4 bytes,
* the MTU of a VLAN interface is still 1500.
If your Network adapter/driver can't handle larger frames, you can:
* update the driver,
* write a bug report for the driver,
* replace the adapter with one that can.
The problem with lowering the MTU is that when bridging the VLAN to untagged
ports you will have to adjust the MTU of the interfaces of all hosts
connected to these ports.
If you still want to use that workaround, just add an option "mtu 1496" to
/etc/network/interfaces, but make sure you do this on all connected systems.
I hope closing this (non-)bug is OK with the maintainer.
Timo
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