Interface MTU configuration makes the interface down

Installing and Using OpenWrt Network and Wireless Configuration
1

Hi everyone, I tried to configure MTU on the interface by adding an entry in the /etc/config/network file and reload the network service. But after reloading the network service is going down.

This is the below information in /etc/config/network
config interface 'LAN14'
option ifname 'et1_1'
option proto 'static'
option ipaddr '192.168.2.1'
option netmask '255.255.255.0'
option mtu '1500'

37: et1_1: <BROADCAST,MULTICAST> mtu 1500 qdisc mq state DOWN mode DEFAULT group default qlen 1000

2

To be clear, the same configuration works if you omit option mtu '1500' - correct?

3

Hi

i remember that was having trouble with lower line (underscore) char in configs, so maybe try to remove _

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4

nope.... Once the interface is down and if option mtu '1500' is omitted then it also the interface doesn't come up after a reboot

5

Hi,
I tried it without underscore and its still not working....
config interface 'LAN14'
option ifname 'et1'
option proto 'static'
option ipaddr '192.168.2.1'
option netmask '255.255.255.0'
option mtu '4200'
37: et1: <BROADCAST,MULTICAST> mtu 4200 qdisc mq state DOWN mode DEFAULT group default qlen 1000
link/ether ec:8a:48:04:27:fd brd ff:ff:ff:ff:ff:ff

6

Then I'm not understanding why your post says there's an issue is with the MTU configuration, can you explain?

I don't want to make false assumptions - please explain why this second config say MTU 4200?

7

et1 is also probably misconfigured. Please proof read your config before complaining.

And yes, mtu of 4200 bytes sounds broken for most low budget plastic boxes....

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