Ubuntu
debian-installer package

  1. Bug #1541544
  2. Comment #3

Comment 3 for bug 1541544

Revision history for this message
bugproxy (bugproxy) wrote : Comment bridged from LTC Bugzilla

------- Comment From <email address hidden> 2016-02-05 10:37 EDT-------
Hi Dimitri,

well done, your investigation and research! Thank you that you took the time to dig deeply into that, even into kernel code. Great work!

Here my answers:

IIRC the kernel has for the qeth module layer2=1 set as the default. To use layer3 (layer2=0), it needs to be set explicitely. Which means, if noone changes the sysfs entry for layer2, layer 2 will be used as default. For some setups it might be required to have layer3, thus it is mandatory to ask.

An configuration check like for x64 arch will usually not work in a mainframe/enterprise environment, may it be due to the lack of dhcp server or to stringent firewalls.

And now to your last three questions:

Q1: ideally kernel and/or with udev assistance would do the autodiscovery of the required mode, if possible.
A1: yes, that would be preferable, but IIRC for qeth is is the user's responsibilty to choose the correct layer2 setting, according to the network admin's advice.

> Use this device in layer2 mode?
> The qeth network driver is used for OSA-Express cards, HiperSockets and similar devices.
> Using the card in layer2 mode will make it keep the MAC addresses of IPv4 packets.
> Alternative is to use layer3 mode, in that mode LLC headers are removed from incoming
> IPv4 packets. Incorrect mode will lead to lack of connectivity.
Q2: does the proposed new wording sound better to you? or how would you like the question to be worded?
A2: Yes, good and crispy wording! I totally agree, but please move the question "Use this device in layer2 mode?" to the end, as it was before => and then it looks like this:
The qeth network driver is used for OSA-Express cards, HiperSockets and similar devices. Using the card in
layer2 mode will make it keep the MAC addresses of IPv4 packets. Alternative is to use layer3 mode, in that
mode LLC headers are removed from incoming IPv4 packets. Incorrect mode will lead to lack of connectivity.
Use this device in layer2 mode?

Q3: should I keep layer2 as default?
A3: yes, please. It is for almost all cases the recommended layer mode.