Bug 620662 – net-misc/networkmanager-1.8.0: infinite loop when changing MTU

• Product: Gentoo Linux
• Status: RESOLVED UPSTREAM

[Description cyrillic 2017-06-04 00:18:05 UTC]

networkmanager-1.8.0 + dhcpcd can no longer connect to a 9000 MTU network, but this was working with networkmanager-1.4.4 + dhcpcd.

Reproducible: Always

[Comment 1 cyrillic 2017-06-04 00:19:19 UTC]

Created attachment 475130 [details]
networkmanager_looping.txt

[Comment 2 Mike Gilbert 2017-06-04 00:38:14 UTC]

networkmanager-1.4.4 did not have dhcpcd support enabled.

Are you able to reproduce this with dhclient or the built-in dhcp support?

[Comment 3 cyrillic 2017-06-04 01:09:10 UTC]

(In reply to Mike Gilbert from comment #2)
> networkmanager-1.4.4 did not have dhcpcd support enabled.
It did after I patched the ebuild :)

> Are you able to reproduce this with dhclient or the built-in dhcp support?
I have not tried a recent version of dhclient, but in the past, it did not support changing MTU where dhcpcd did.

[Comment 4 Mike Gilbert 2017-06-04 02:24:19 UTC]

I would suggest you work with the upstream developers of NetworkManager and dhcpcd to resolve this.

[Comment 5 cyrillic 2017-06-04 14:48:26 UTC]

I have now tried the available DHCP clients.

dhclient : ignores MTU option from server
dhcpcd : loops
internal : loops

I think one of the internal timeouts has been shortened in networkmanager-1.8.0, and it gives-up before the MTU change can complete.

[Comment 6 Mike Gilbert 2017-06-04 15:33:05 UTC]

(In reply to cyrillic from comment #5)

Thanks for testing.

[Comment 7 cyrillic 2017-06-05 23:13:39 UTC]

Created attachment 475314 [details, diff]
disconnect_delay.patch

I am not sure if this is hardware specific, but MTU change takes right around 4 seconds for me, and relaxing this timeout completely fixes the problem I was having.

Tested on networkmanager-1.8.0 and networkmanager-9999, Intel 1Gb and 10Gb ethernet.

[Comment 8 Cyril 2017-06-12 07:59:51 UTC]

Same problem here since networkmanager-1.8.0.
Intel 82567LM Gigabit
Intel 82574L Gigabit

The problem appears on all my locally configured machines with a 9000 MTU and autoconnected.
In manual connection, this works correctly.

The patch works for my case.

Thanks Cyrillic

[Comment 9 Cyril 2017-11-28 12:24:57 UTC]

Created attachment 506916 [details, diff]
device-carrier-wait-timeout

[Comment 10 Cyril 2017-11-28 12:26:15 UTC]

fixed upstream https://cgit.freedesktop.org/NetworkManager/NetworkManager/commit/?id=eb95d6bbbb6982dac78949368fc8b2512aa906bb

[Comment 11 cyrillic 2017-12-03 02:12:05 UTC]

Does this mean the timeout can now be changed in a config file somewhere ?