Force interface up without link?

fdmillion · 2017-11-27 18:40:16

Can I force netctl to bring up an interface even if there is no physical link on the interface at boot time?

My scenario: My Arch server is a file server and NAS. It has two interfaces - the primary Gigabit interface which leads to my LAN, and a secondary 10G Ethernet interface which is directly connected (no switch) via a Twinax cable to my virtual machine host.

The NAS boots faster than the virtualization server; by the time it is trying to bring up interfaces, the VM server still has not "enabled" the 10G interface. Therefore, the Arch install sees the interface as having no carrier. Netctl then fails to bring up the interface and simply gives up.

This means that each time I reboot my servers simultaneously (e.g. after a power failure), the VM server is unable to find its storage. When the VM server ultimately brings up its 10G interface, Arch has already "given up" looking for a carrier and simply leaves the interface down. This throws all sorts of warnings on the VM server. The easiest fix for me is to login to the NAS, bring the interface up manually, then reboot the VM server. The VM server's taking the interface down during reboot doesn't affect Arch, and once it reboots the storage is mounted OK and all is well. But this is annoying and means the system cannot come back up without manual intervention.

Hence, my desire to ask Netctl to simply bring up the interface WITHOUT looking for a carrier. The interface is configured with a static IP as there is obviously no DHCP server needed on a point-to-point link. Can this be done?

seth · 2017-11-27 21:18:49

https://wiki.archlinux.org/index.php/Ne … out_issues ?

fdmillion · 2017-12-26 04:44:28

Is the only option to increase the timeouts? Is there any way on a static-configured interface to just say "bring it up regardless"?

This could become a chicken-and-egg problem on another setup I am experimenting with. One of two directly-connected hosts is going to have to bring its interface up first without any carrier from the other, in order for the other to see the carrier in the first place...

seth · 2017-12-26 09:13:39

Sorry, I didn't really read your specific setup details (I'm lazy as shit - and the typical answer to the subject line is "wait longer for the carrier" ;-)

So see the green box in https://wiki.archlinux.org/index.php/Ne … figuration
Also to be found in netctl's manpage, btw :-P

Arch Linux

#1 2017-11-27 18:40:16

Force interface up without link?

#2 2017-11-27 21:18:49

Re: Force interface up without link?

#3 2017-12-26 04:44:28

Re: Force interface up without link?

#4 2017-12-26 09:13:39

Re: Force interface up without link?

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