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Bug 1623520 - cannot change mtu on Sierra Wireless EM7345
Summary: cannot change mtu on Sierra Wireless EM7345
Keywords:
Status: CLOSED NOTABUG
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: NetworkManager
Version: 7.6
Hardware: Unspecified
OS: Unspecified
medium
medium
Target Milestone: rc
: ---
Assignee: Thomas Haller
QA Contact: Desktop QE
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2018-08-29 14:22 UTC by Vladimir Benes
Modified: 2020-06-11 11:31 UTC (History)
10 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of: 1460217
Environment:
Last Closed: 2020-06-11 11:31:16 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)

Description Vladimir Benes 2018-08-29 14:22:43 UTC 
I was trying to change mtu via gsm.mtu buth I see this error. MTU cannot be changed via ip either. Is that a kernel bug? For now I am pushing to NM.

I see error like this:
Aug 29 08:23:20 gsm-r5s2-01.wlan.rhts.eng.bos.redhat.com NetworkManager[18886]: <debug> [1535545400.6287] platform: link: setting 'wwp0s20u2' (25) mtu 1600
Aug 29 08:23:20 gsm-r5s2-01.wlan.rhts.eng.bos.redhat.com NetworkManager[18886]: <debug> [1535545400.6287] platform-linux: link: change 25: mtu: 1600
Aug 29 08:23:20 gsm-r5s2-01.wlan.rhts.eng.bos.redhat.com NetworkManager[18886]: <debug> [1535545400.6288] platform-linux: do-request-link: 25
Aug 29 08:23:20 gsm-r5s2-01.wlan.rhts.eng.bos.redhat.com NetworkManager[18886]: <debug> [1535545400.6288] platform-linux: do-change-link[25]: success changing link: success
Aug 29 08:23:20 gsm-r5s2-01.wlan.rhts.eng.bos.redhat.com NetworkManager[18886]: <debug> [1535545400.6288] platform-linux: sysctl: setting '/proc/sys/net/ipv6/conf/wwp0s20u2/mtu' to '1600' (current value is '1500')
Aug 29 08:23:20 gsm-r5s2-01.wlan.rhts.eng.bos.redhat.com NetworkManager[18886]: <debug> [1535545400.6288] platform-linux: sysctl: failed to set '/proc/sys/net/ipv6/conf/wwp0s20u2/mtu' to '1600': (22) Invalid argument
Aug 29 08:23:20 gsm-r5s2-01.wlan.rhts.eng.bos.redhat.com NetworkManager[18886]: <warn>  [1535545400.6288] device (cdc-wdm0): mtu: failure to set IPv6 MTU

echo 1600 > /proc/sys/net/ipv6/conf/wwp0s20u2/mtu doesn't work either

Any idea? RHEL7.6 
kernel-3.10.0-935.el7.x86_64
ModemManager-1.6.10-1.el7.x86_64
NetworkManager-1.12.0-3.el7.x86_64

I think I was able to change it before, have to find out when.
Comment 2 Lubomir Rintel 2019-03-27 17:33:21 UTC 
If it worked, then perhaps with a different device, or this one got a firmware update. Did a larger MTU actually work?

Or perhaps qmi_wwan gained support for the device and it's now using the CDC instead of PPP?

# lsusb -vvvv
...
Bus 003 Device 026: ID 1199:a001 Sierra Wireless, Inc.
...
      CDC Ethernet:
        iMacAddress                      6 FFFFFFFFFFFF
        bmEthernetStatistics    0x00000000
        wMaxSegmentSize               1514

In any case -- it works the way it is supposed to. This device only supports the MTU of 1500.
Comment 3 Marcelo Ricardo Leitner 2019-07-03 15:11:26 UTC 
Mass-moving bugs RHEL <= 7.6.0 to 7.7.0.
As we are past RFE deadline for 7.7.0 and we should have no new features on 7.8.0, please evaluate if it's still wanted on RHEL7 and contact PM for exception. You may also move it to RHEL8 if that's wanted. Thanks!
Comment 5 Till Maas 2020-06-05 08:07:14 UTC 
(In reply to Lubomir Rintel from comment #2)
> If it worked, then perhaps with a different device, or this one got a
> firmware update. Did a larger MTU actually work?
> 
> Or perhaps qmi_wwan gained support for the device and it's now using the CDC
> instead of PPP?
> 
> # lsusb -vvvv
> ...
> Bus 003 Device 026: ID 1199:a001 Sierra Wireless, Inc.
> ...
>       CDC Ethernet:
>         iMacAddress                      6 FFFFFFFFFFFF
>         bmEthernetStatistics    0x00000000
>         wMaxSegmentSize               1514
> 
> In any case -- it works the way it is supposed to. This device only supports
> the MTU of 1500.

Vlad, can we close this as NOTABUG since you are not sure that it worked in past?
Comment 6 Vladimir Benes 2020-06-11 11:31:16 UTC 
It looks it's not supported anyway. Closing.
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