How to set up jumbo frames permanently?

English Network/Internet
1

Hello,

if I set the MTU value manually, like


ifconfig eth0 mtu 6122

I can get an MTU up to 6122. However, if I put this value into the appropriate network config file, I am back at MTU 1500 after reboot.

How to set up jumbo frames permanently?

2

You seem to think to know what is the appropriate network config file and how to configure there. How do you think we can check if you are correct in these assumptions if you do not tell us exactly which file and what you put there?

3

/etc/sysconfig/network/ifcfg-eth0:


BOOTPROTO='static'
BROADCAST=''
ETHTOOL_OPTIONS=''
IPADDR='192.168.1.2/24'
MTU='6122'
NAME='RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller'
NETWORK=''
REMOTE_IPADDR=''
STARTMODE='auto'
4

Those are computer facts! Thanks.
To me that looks fine.

Do you use wicked or NetworkManager?

5

And when using wicked, did you try to set it using YaST > Network Devices > Networksettings, or by editing the file?

6

I use NetworkManager, and I tried yast and editing directly.

7

Using YaST implies that you switch to wicked.

In fact I have almost nil knowledge of NetworkManager, I do not even know if it uses the ifcfg files or uses it’s own. I guess it uses it’s own.

8

Am Tue, 28 Feb 2017 18:56:02 GMT
schrieb hcvv <hcvv@no-mx.forums.microfocus.com>:

> I guess it uses it’s own.

Correct (and MTU can be configured there).

AK

–
Never attribute to malice that which can be adequately explained by stupidity.
(R.J. Hanlon)

9

It can be configured via the NM connection-editor, or directly in the configuration files which are located in /etc/NetworkManager/system-connections/ directory. For example, if MTU is set manually (say 1522 bytes), it will appear in the connection definition like this

[Ethernet]
mtu=1522
10

Sorry, I double checked: I am indeed using wicked.

11

Have you verified that your hardware NIC supports the size jumbo frames you’re trying to configure?
And, is your physical network connection point to point or have verified that all intermediate devices like switches similarly support the size you’re trying to configure?

Also, FYI
Although Jumbo Frames is a Layer 2 implementation to transfer super sized packets,
Another way to greatly increase throughput is to modify Layer 3 Window Scaling.
This is mentioned briefly with little comment along with other configurable network options in the community openSUSE docuementation
https://doc.opensuse.org/documentation/leap/tuning/html/book.sle.tuning/cha.tuning.network.html

And, I describe along with a number of other optimizations in a paper I wrote for an earlier openSUSE which is still relevant today
https://sites.google.com/site/4techsecrets/optimize-and-fix-your-network-connection

TSU