RB433GL MTU problem after upgrade to 6.30?!

RouterOS General
1

After upgrading to version 6.30 I noticed max L2MTU on ethernet port ether1 is 1520?
This is in accordance with the table at http://wiki.mikrotik.com/wiki/Manual:Maximum_Transmission_Unit_on_RouterBoards.
But in previous versions of ROS RB433GL reports L2MTU on Ether1 1524.
What is happening now, we have a problem with MPLS links whose MPLS Interface MTU is 1524.
If L2MTU was incorrectly shown in previous versions of ROS, how is it that we only now experiencing problems with MPLS?

2

Has anyone noticed this already? :open_mouth:

RoS: 6.30

routerboard: yes
model: 433GL
serial-number: **********
current-firmware: 3.18



Flags: D - dynamic, X - disabled, R - running, S - slave

NAME TYPE ACTUAL-MTU L2MTU MAX-L2MTU MAC-ADDRESS

0 R ether1 ether 1500 1520 1520 00:0C:42:
1 ether2 ether 1500 1520 1520 00:0C:42:
2 R ether3 ether 1500 1520 1520 00:0C:42:

RoS:6.24

Flags: D - dynamic, X - disabled, R - running, S - slave

NAME TYPE ACTUAL-MTU L2MTU MAX-L2MTU MAC-ADDRESS

0 RS ether1 ether 1500 1524 1524 00:0C:42:
1 RS ether2 ether 1500 1524 1524 00:0C:42:
2 S ether3 ether 1500 1524 1524 00:0C:42:



routerboard: yes
model: 433GL
serial-number: ***************
current-firmware: 3.18

3

Since v6.27 it was necessary to reduce max L2MTU size of RB411GL/RB433GL to fix packet loss problem. It resulted in a bad TCP performance in real life applications.

4

But now results in MPLS problems :blush:
So what to do now, when we need a minimum L2MTU 1524?