[quagga-users 14953] problem with ospf6 MTU VLAN interface

[Bartłomiej Solarz-Niesłuchowski]

Dear list,

I have strange problem with ospf6d + VLAN interface + fedora 27.

in ospf6d config file(on disk) i have:
interface enp1s0f0.224
 ipv6 ospf6 cost 1
 ipv6 ospf6 network broadcast

BUT after rebooting serwer when i log in to management console:
sh run
interface enp1s0f0.224
 ipv6 ospf6 ifmtu 1504
 ipv6 ospf6 cost 1
 ipv6 ospf6 network broadcast

interface has MTU 1500 bytes:
sh interface enp1s0f0.224
Interface enp1s0f0.224 is up, line protocol is up
  Link ups:       1  last: Thu, 22 Feb 2018 16:34:20 +0100
  Link downs:     0  last: (never)
  vrf: 0
  index 4 metric 0 mtu 1500
  flags: <UP,BROADCAST,RUNNING,MULTICAST>
  Type: Unknown
  HWaddr: 00:1e:67:37:67:bc
  inet 213.135.44.139/28 broadcast 213.135.44.143
  inet6 fe80::21e:67ff:fe37:67bc/64
  inet6 2001:1a68:a:3000::139/64

WHY config automatically changing????

(tested quagga 1.2.4)