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 chipset and then the L2MTU was decreased according this limit and then it will still 1520 also for new release. the use of 5.5 (L2MTU 1522) is deprecated and at my own risk.
ok, but i have a lot of gigabit routerboards in my network, all configured with MPLS+VPLS. i need to change all boards to be able to upgrade to ros >5.5?
any other with the same problem?

thanks,

Michele Pietravalle

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 chipset and then the L2MTU was decreased according this limit and then it will still 1520 also for new release. the use of 5.5 (L2MTU 1522) is deprecated and at my own risk.
ok, but i have a lot of gigabit routerboards in my network, all configured with MPLS+VPLS. i need to change all boards to be able to upgrade to ros >5.5?
any other with the same problem?

thanks,

Michele Pietravalle

Here is an older discussion of MPLS with these chipsets:
http://forum.mikrotik.com/viewtopic.php?f=3&t=40743

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 chipset and then the L2MTU was decreased according this limit and then it will still 1520 also for new release. the use of 5.5 (L2MTU 1522) is deprecated and at my own risk.
ok, but i have a lot of gigabit routerboards in my network, all configured with MPLS+VPLS. i need to change all boards to be able to upgrade to ros >5.5?
any other with the same problem?

thanks,

Michele Pietravalle

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 control, I downgraded to 5.11 with the same result.
Tried out each and every version down to 5.7 and no go.
Downgraded back to 5.6 and the L2MTU was back up to 1524.
Seems like 5.6 was the last one with 1524 L2MTU. FW right now is still 2.36, which came with 5.7, instead of 2.29 which came with 5.6. We'll see how it works out.
Checking the pdf's, I found that the specs for all those similar G boards were changed silently sometime ago from 1524 down to 1520 L2MTU.
There goes down the drain my hope for a fix for the port-flapping issue and the OSPF NBMA bug.
Looks like I'm locked to 5.6 for ever.
Knowing this, I'd have paid 120$ more for a RB1100 instead.

Really nice move Mikrotik!
It's getting better every day.

Thank you.
Bernardo

Here is an older discussion of MPLS with these chipsets:
http://forum.mikrotik.com/viewtopic.php?f=3&t=40743

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.

Here is an older discussion of MPLS with these chipsets:
http://forum.mikrotik.com/viewtopic.php?f=3&t=40743

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?