Hyper-v / Centos 7 / Jumbo Frames

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ssherman
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Hyper-v / Centos 7 / Jumbo Frames

Post by ssherman » 2018/05/08 22:05:54

I am trying to enable jumbo frames on my centos 7 server, but the network goes down and the command never completes when I try.

command:
ifconfig eth1 mtu 9000


No errors in /var/log/messages

ssherman
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Joined: 2017/07/21 18:27:36

Re: Hyper-v / Centos 7 / Jumbo Frames

Post by ssherman » 2018/05/09 03:30:51

I tried a fresh install of centos 7 and it still doesn't work....

I went ahead and downloaded a copy of Fedora and I have working there.

[root@nfs ~]# ip link show dev eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc mq state UP mode DEFAULT group default qlen 1000
link/ether 00:15:5d:00:04:08 brd ff:ff:ff:ff:ff:ff
[root@nfs ~]# uname -r
4.16.6-302.fc28.x86_64
[root@nfs ~]#

hunter86_bg
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Re: Hyper-v / Centos 7 / Jumbo Frames

Post by hunter86_bg » 2018/05/09 04:25:39

Can you try with:

Code: Select all

ip link set dev eth0 mtu 9000
If the driver doesn't support custom MTU sizes or the size you are trying to set, you will recieve "SIOCSIFMTU: Invalid argument".
Source: Solution 3643.

ssherman
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Re: Hyper-v / Centos 7 / Jumbo Frames

Post by ssherman » 2018/05/09 04:45:33

hunter86_bg wrote:Can you try with:

Code: Select all

ip link set dev eth0 mtu 9000
If the driver doesn't support custom MTU sizes or the size you are trying to set, you will recieve "SIOCSIFMTU: Invalid argument".
Source: Solution 3643.

I have tried with the "ip link set dev eth0 mtu 9000" , ifconfig, and modifying the ifcfg-eth0 script with a reboot.

"ip link set dev eth0 mtu 9000" : Brings down all the interfaces
"ifconfig eth1 mtu 9000" : Brings down all the interfaces
"ifcfg-eth0 script" : boots just fine, but when I do a "ip link show dev eth0" it brings down all the interfaces

pjwelsh
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Re: Hyper-v / Centos 7 / Jumbo Frames

Post by pjwelsh » 2018/05/09 14:42:51

If you have the Network Manager CLI it should be as simple as:
nmcli connection modify eth0 802-3-ethernet.mtu 9000

But the other option should have worked also. It may be a good idea to post your ifcfg-eth0 script. Could very be the driver used is not liking it.

One note I saw was to make sure you have Hyper-V Linux Integration Services (LIS).

Keep us posted on progress.
Thanks
pjwelsh

hunter86_bg
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Re: Hyper-v / Centos 7 / Jumbo Frames

Post by hunter86_bg » 2018/05/09 15:56:13

What is the kernel module used for your nic?

ssherman
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Re: Hyper-v / Centos 7 / Jumbo Frames

Post by ssherman » 2018/05/10 01:59:53

nstalled Packages
Name : hyperv-daemons
Arch : x86_64
Version : 0
Release : 0.30.20161211git.el7
Size : 0.0
Repo : installed
From repo : base
Summary : HyperV daemons suite
URL : http://www.kernel.org
License : GPLv2
Description : Suite of daemons that are needed when Linux guest
: is running on Windows Host with HyperV.

[root@plex ~]# ethtool -i eth0
driver: hv_netvsc
version:
firmware-version: N/A
expansion-rom-version:
bus-info:
supports-statistics: yes
supports-test: no
supports-eeprom-access: no
supports-register-dump: no
supports-priv-flags: no

hunter86_bg
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Re: Hyper-v / Centos 7 / Jumbo Frames

Post by hunter86_bg » 2018/05/10 04:39:21

Once Linux Integration services are deployed, virtual machines running Linux distributions can use features like Live Migration, Jumbo Frames, VLAN Tagging and Trunking, support for Symmetric multiprocessing (SMP), Static IP Injection, VHDX resize, Virtual Fibre Channel, Live Virtual Machine Backup and the ability to perform hot adding and removal of memory using the Dynamic Memory feature of Hyper-V.
If this is true, you need the LIS in order to use jumbo frames.Did you install it?

Source: Some Article

ssherman
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Re: Hyper-v / Centos 7 / Jumbo Frames

Post by ssherman » 2018/05/10 17:12:14

This track is what our documentation refers to as “built-in”. You get LIS from the distro vendor as part of the distro release. And if you upgrade from CentOS 7.0 to 7.1, you’ll get updated LIS with the 7.1 update, just like any other Linux kernel updates. Same from 7.1 to 7.2. This track is the easiest track, because you don’t do anything special or extra for LIS – it’s just part of the distro release. It’s important to note that we don’t assign a version number to the LIS that you get this way. The specific set of LIS changes that you get depends on exactly when the distro vendor pulled the latest updates from the upstream Linux kernel, what they were able to include (they often don’t include every change due to the risk of destabilizing), and various other factors. The tradeoff with the “built-in” approach is that you won’t always have the “latest and greatest” LIS code because each distro release is a snapshot in time. You can upgrade to a later distro version, and, for example, CentOS 7.2 will be a later snapshot than CentOS 7.1. But there are inherent delays in the process. Distro vendors have freeze dates well in advance of a release so they can test and stabilize. And, CentOS, in particular, depends on the equivalent RHEL release.
For LIS 4.2 it is already part of the OS and the added tools for hyper-v is the hyperv-daemon , which is installed. Like I said earlier I did a fresh install with Fedora (with updates) and it is working just fine, but a fresh install with updates on centos is a no go.

hunter86_bg
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Re: Hyper-v / Centos 7 / Jumbo Frames

Post by hunter86_bg » 2018/05/13 06:43:31

Try with CentOS 7.5.1804 and if it is going on, then report a bug in bugs.centos.org

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