Hi, i have the problem that after the upgrade of the RB/450G to Ros 5.7 the L2MTU was 1520 and before was 1522. This is a VERY VERY VERY VERY BIG PROBLEM for the people that uses this hardware with MPLS&VPLS, because 1500+14+4+4=1522!! Mikrotik support answer me that is a problem of ehternet chipse…

Hi, I know I’m pretty late on this, but I got caught today, trying to upgrade 4 brand new RB493G boards. Importing the config from the old 450G, still running on 5.6, with L2MTU set to 1524 worked, till I decided to upgrade to 5.12, where my L2MTU got decreased to 1520. Trying to get this under …

I don’t see how that is relevant to the L2MTU being lowered. I also don’t see any mention of this in the changelog.

I don’t see how that is relevant to the L2MTU being lowered. I also don’t see any mention of this in the changelog. me neither that’s exactly why I wrote “silently” in the above posting looks to me like no one cares… saludos Bernardo

Can somebody from MikroTik please explain why this was changed?

L2MTU decreased on "G series" after upgrade to 5.7

Hardware MikroTik hardware general

jandafields November 12, 2011, 6:50pm 2

Here is an older discussion of MPLS with these chipsets:
http://forum.mikrotik.com/t/routerboard-433ah-3v1-chipset-problem-ip175d/36800/1