Always exclude this address from any defined range. This address will never be assigned by the DHCP server.

Ok, it will exclude in any range.
Forget about it

Fixed in https://github.com/vyos/vyos-1x/commit/84b520dd580b7725de4c9e62b11ec490cb8d3f4f. The 1.4.0-epa2 build was created before the patch was applied.

comments above are for https://vyos.net/get/nightly-builds/

vyos@vyos:~$ show version
Version: VyOS 1.3-rolling-202005100117
Release Train: equuleus

same of

I don't see any problem on user receive message telling him MTU is not accepted by OS when his commit
On Juniper it is very common case

My suggestion: if you do a MTU suggestor/validation should be a tool optional outsite configure

great work @thomas-mangin I was reading your code

Hardware vendor: Red Hat
Hardware model: OpenStack Compute
MTU should be max 1450

https://github.com/vycontrol/vycontrol/issues/27

In T2404#62721, @jjakob wrote:

@c-po is it possible to detect the exact networking setup used on the host? If not, I don't think that'll do any good, because the hypervisor is just that - a hypervisor. There can be many different types of networking. Like in this case, Openstack's SDN supports a lower MTU than a bridged or NATed connection with the same hypervisor would. The only reliable way is to detect the max MTU in some way (the kernel/device driver must know this, the question how can we read it) - the first step is to not touch the default MTU if the user doesn't set it.

My suggestion:

• if someone set a higher MTU than OS support, commit fail will be ok and that's OK, each vyos admin should know his OS limitations

Other ubuntu servers inside same openstack max mtu OS leave at 1450 too

In T2404#62637, @robertoberto wrote:

I tried to google to find out how to discover max mtu an interface accept but not found.

I guess limitation is because we are using OpenStack KVM or the other guy is using VMware and they use some bytes to their SDN

I tried to google to find out how to discover max mtu an interface accept but not found.

In T2404#62624, @thomas-mangin wrote:

An issue to change the MTU should not fail the whole interface change but just this one but the code does not not allow this easily. I will try to work on this.

vyos@vyos:~$ show version
Version: VyOS 1.3-rolling-202004230117
Release Train: equuleus

In T2404#62621, @robertoberto wrote:

Here:

root@vyos:~# cat /sys/class/net/eth0/mtu
1450
root@vyos:~# echo 1500 > /sys/class/net/eth0/mtu
-bash: echo: write error: Invalid argument
root@vyos:~# echo 1460 > /sys/class/net/eth0/mtu
-bash: echo: write error: Invalid argument
root@vyos:~# echo 1440 > /sys/class/net/eth0/mtu
root@vyos:~# echo 1441 > /sys/class/net/eth0/mtu
root@vyos:~# echo 1442 > /sys/class/net/eth0/mtu
root@vyos:~# echo 1443 > /sys/class/net/eth0/mtu
root@vyos:~# echo 1449 > /sys/class/net/eth0/mtu
root@vyos:~# echo 1450 > /sys/class/net/eth0/mtu
root@vyos:~# echo 1460 > /sys/class/net/eth0/mtu
-bash: echo: write error: Invalid argument
root@vyos:~# echo 1455 > /sys/class/net/eth0/mtu
-bash: echo: write error: Invalid argument
root@vyos:~# echo 1453 > /sys/class/net/eth0/mtu
-bash: echo: write error: Invalid argument
root@vyos:~# echo 1452 > /sys/class/net/eth0/mtu
-bash: echo: write error: Invalid argument
root@vyos:~# echo 1451 > /sys/class/net/eth0/mtu
-bash: echo: write error: Invalid argument
root@vyos:~#

root@vyos:~# cat /sys/class/net/eth0/mtu
1450
root@vyos:~# echo 1500 > /sys/class/net/eth0/mtu
-bash: echo: write error: Invalid argument
root@vyos:~# echo 1460 > /sys/class/net/eth0/mtu
-bash: echo: write error: Invalid argument
root@vyos:~# echo 1440 > /sys/class/net/eth0/mtu
root@vyos:~# echo 1441 > /sys/class/net/eth0/mtu
root@vyos:~# echo 1442 > /sys/class/net/eth0/mtu
root@vyos:~# echo 1443 > /sys/class/net/eth0/mtu
root@vyos:~# echo 1449 > /sys/class/net/eth0/mtu
root@vyos:~# echo 1450 > /sys/class/net/eth0/mtu
root@vyos:~# echo 1460 > /sys/class/net/eth0/mtu
-bash: echo: write error: Invalid argument
root@vyos:~# echo 1455 > /sys/class/net/eth0/mtu
-bash: echo: write error: Invalid argument
root@vyos:~# echo 1453 > /sys/class/net/eth0/mtu
-bash: echo: write error: Invalid argument
root@vyos:~# echo 1452 > /sys/class/net/eth0/mtu
-bash: echo: write error: Invalid argument
root@vyos:~# echo 1451 > /sys/class/net/eth0/mtu
-bash: echo: write error: Invalid argument
root@vyos:~#

In T2404#62515, @jjakob wrote:

@robertoberto issue (cannot change udp fragmentation-offload) is not the same as the original post (changing MTU out of range) so please create a separate task for it.

same here
root@vyos:~# ls -la /tmp/vyos.log.debug
-rw-r--r-- 1 vyos users 0 May 1 18:03 /tmp/vyos.log.debug
root@vyos:~# /sbin/ethtool -K eth0 ufo off
Cannot change udp-fragmentation-offload