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How to set MTU value for an Open vSwitch bridge from command line?

I have tried man pages, I failed.

Thank you.

Shan
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3 Answers3

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The bridge MTU is automatically set to the smallest port MTU. So you just have to set the MTU of each port of the bridge. You can get a list of them via ovs-vsctl list-ports <BRIDGENAME>.

Ferenc Wágner
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  • So glad that you posted this answer. I had been scouring the net for a while in search of an answer. I found that I had the MTU unset on one of my ports in the br-ex in my OpenStack environment and even though that port wasn't being used, it kept the MTU at the default 1500. After you use the ```ovs-vsctl list-ports ``` you could create a quick bash loop to change the MTUs to 9000 (or whatever value supported by the card). My bash script would look like this: ```for i in $(ovs-vsctl list ports );do ip link set mtu 9000 dev $i;done;ip a show ``` – 86bornprgmr May 04 '16 at 05:57
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ifconfig "ovs bridge" mtu $value up

This is a temporary modification, it will reset after reboot

Georges DAMIEN
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Example:

ovs-vsctl set int br0 mtu_request=1450

This will make the change persist in the DB. Changes made through ip or ifconfig will not persist

The mtu_request column can be used to configure MTU even for physical interfaces (e.g. eth0).

OVS sets the Bridge MTU to that of the lowest Port. So you may have to adjust the MTU on other Bridge Ports before you get the result you want.

http://docs.openvswitch.org/en/latest/faq/issues/
2nd Q&A from bottom of page

xdfil
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