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<span style="font-weight:bold">From: </span><<a href="mailto:users-bounces@openvz.org">users-bounces@openvz.org</a>> on behalf of Axton <<a href="mailto:axton.grams@gmail.com">axton.grams@gmail.com</a>><br>
<span style="font-weight:bold">Reply-To: </span>OpenVZ users <<a href="mailto:users@openvz.org">users@openvz.org</a>><br>
<span style="font-weight:bold">Date: </span>Sunday 28 February 2016 20:27<br>
<span style="font-weight:bold">To: </span>OpenVZ users <<a href="mailto:users@openvz.org">users@openvz.org</a>><br>
<span style="font-weight:bold">Subject: </span>[Users] Virtuozzo7 beta - jumbo frames on veth<br>
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<div dir="ltr">I need to configure some veth interfaces with jumbo frames. I can setup everything properly on the host where the interfaces all have mtu 9000:
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<div>2: enp0s20f0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc mq master team0 state UP mode DEFAULT qlen 1000</div>
<div> link/ether 0c:c4:7a:6b:95:55 brd ff:ff:ff:ff:ff:ff</div>
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<div>3: enp0s20f1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc mq master team0 state UP mode DEFAULT qlen 1000</div>
<div> link/ether 0c:c4:7a:6b:95:55 brd ff:ff:ff:ff:ff:ff</div>
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<div>4: enp0s20f2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc mq master team0 state UP mode DEFAULT qlen 1000</div>
<div> link/ether 0c:c4:7a:6b:95:55 brd ff:ff:ff:ff:ff:ff</div>
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<div>5: enp0s20f3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc mq master team0 state UP mode DEFAULT qlen 1000</div>
<div> link/ether 0c:c4:7a:6b:95:55 brd ff:ff:ff:ff:ff:ff</div>
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<div>7: team0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc noqueue state UP mode DEFAULT</div>
<div> link/ether 0c:c4:7a:6b:95:55 brd ff:ff:ff:ff:ff:ff</div>
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<div>46: team0.97@team0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc noqueue master vmbr97 state UP mode DEFAULT</div>
<div> link/ether 0c:c4:7a:6b:95:55 brd ff:ff:ff:ff:ff:ff</div>
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<div>47: vmbr97: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc noqueue state UP mode DEFAULT</div>
<div> link/ether 0c:c4:7a:6b:95:55 brd ff:ff:ff:ff:ff:ff</div>
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<div>When I start a container with a veth interface on vmbr97, the bridge interface falls back to mtu 1500:<br>
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<div>[root@cluster-02 network-scripts]# prlctl start <a href="http://ha21t02dh.tech.abc.org">
ha21t02dh.tech.abc.org</a></div>
<div>Starting the CT...</div>
<div>The CT has been successfully started.</div>
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<div>[root@cluster-02 network-scripts]# ip link show vmbr97</div>
<div>47: vmbr97: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT</div>
<div> link/ether 0c:c4:7a:6b:95:55 brd ff:ff:ff:ff:ff:ff</div>
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<div>brctl shows that this container is the only one on this network:</div>
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<div>[root@cluster-02 network-scripts]# brctl show vmbr97</div>
<div>bridge name bridge id STP enabled interfaces</div>
<div>vmbr97 8000.0cc47a6b9555 no team0.97</div>
<div> veth42f2f0a5</div>
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<div>The container is running centos7. I have setup mtu 9000 inside the container:</div>
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<div>CT-6598defa /# cat /etc/sysconfig/network-scripts/ifcfg-eth1</div>
<div>DEVICE=eth1</div>
<div>BOOTPROTO=none</div>
<div>ONBOOT=yes</div>
<div>HOSTNAME=<a href="http://ha21t02dh-c.tech.abc.org">ha21t02dh-c.tech.abc.org</a></div>
<div>NM_CONTROLLED=no</div>
<div>TYPE=Ethernet</div>
<div>MTU=9000</div>
<div>IPADDR=10.1.28.9</div>
<div>PREFIX=22</div>
<div>DEFROUTE=no</div>
<div>IPV6INIT=no</div>
<div>IPV6_AUTOCONF=no</div>
<div>DOMAIN="..."</div>
<div>DNS1=10.0.20.250</div>
<div>DNS2=10.0.20.252</div>
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<div>I can manually fix the issue by setting the mtu to 9000 on the veth interface after the container is started as follows.</div>
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<div>[root@cluster-01 ~]# ip l show vmbr97</div>
<div>47: vmbr97: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT</div>
<div> link/ether 0c:c4:7a:6b:92:56 brd ff:ff:ff:ff:ff:ff</div>
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<div>[root@cluster-01 ~]# ip link set dev veth42346d2f mtu 9000<br>
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<div>[root@cluster-01 ~]# ip l show vmbr97</div>
<div>47: vmbr97: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc noqueue state UP mode DEFAULT</div>
<div> link/ether 0c:c4:7a:6b:92:56 brd ff:ff:ff:ff:ff:ff</div>
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<div>The problem with having to do this each time a container is stopped/started should be obvious.</div>
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<div>My question is this: how do I configure the host and guest so the mtu settings for jumbo frames are setup properly at container start time for the veth interface on the host.</div>
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We don't have such setting (MTU for veth) right now – libvzctl should be patched for it.</div>
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<div><font face="Calibri,sans-serif">Setup of veth params is performed in </font><font face="Andale Mono" style="font-size: 12px;">/usr/libexec/libvzctl/scripts/vz-netns_dev_add,</font><font> O</font>ne can modify it (or vz-functions and add a call of new function
to the vz-netns_dev<span style="font-style: italic;">_</span>add) to add above manual step there. Disadvantage of patching in place is that after libvzctl update these changes will be lost. So, patch to libvzctl is definitely the preferable way to fix it permanently.</div>
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<div>Thank you,</div>
<div>Dmitry.</div>
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<div><font face="Andale Mono" style="font-size: 12px;"> </font></div>
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<div>Axton Grams</div>
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