Network device naming

During our original project to port LCFG to SL7 we were only really considering desktops which typically have a single network interface. To get things working quickly we decided to stick with the “legacy” network device naming scheme which gives us interfaces named like eth0, eth1, eth2, etc. This works just fine with a single interface since we will only ever need access to eth0 but as we’ve moved onto adding network interface bonding for servers we have some discovered some problems. Many of our servers have two controllers each of which has two devices, for maximum reliability we wish to bond over one device from each controller. Traditionally we have done this by naming eth0 as the first device on the first controller and eth1 as the first device on the second controller. We have found with the legacy support on SL7 that this is not possible as they always come out as eth0 and eth2 (eth1 being the second device on the first controller) it seems that the ability to rename interfaces based on MAC address is not working correctly. Due to the way we have configured bonding in LCFG, for simplicity we really would like the two interfaces to continue to be named eth0 and eth1. To resolve this problem we have decided that it is now time to convert to the “modern” naming scheme as described in the Redhat network guide. The interfaces can then be aliased as eth0 and eth1 after they have been configured with their “consistent” names. This appears to work as desired but requires some changes be made in the LCFG headers and we will be working through this transition over the next few weeks. It is likely that the complete change to the default approach will have to wait until the SL7.2 upgrade to ensure we don’t break anything. The first step will be to move the “legacy” support out of the lcfg-level header (lcfg/defaults/network.h) into the ed-level header, this will not have any impact for most users but makes it possible to easily enable and disable the naming schemes for testing purposes. New headers have been provided – lcfg/options/network-legacy-names.h and lcfg/options/network-modern-names.h – to make it easy to swap between the two naming schemes. Once we are confident that this modern approach is reliable we will update the various hardware support headers in the lcfg-level so that it works for the various server models we have in Informatics.

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