New Parameter L2MTU

RouterOS General
1

We have made new parameter L2MTU, which is available for every interface,

/ interface print 
Flags: D - dynamic, X - disabled, R - running, S - slave 
 #     NAME                                        TYPE             MTU   L2MTU
 0  R  ether1                                      ether            1500  1526 
 1  R  ether2                                      ether            1500  1522 
 2     ether3                                      ether            1500  1522 
 3     wlan1                                       wlan             1500  2304 
 4  R  bridge1                                     bridge           1500  1522

More information about the option is available in the Wiki.

2

Thank you. This parameter is very helpful.
Regards,
Andrew

3

why is mtu on all bridge interface 65535 ??

is not that problem when router reboot its loose config.
i see that on your pic bridge mtu is 1522 , and all my bridge interfaces is 65535.

4

65535 is max possible, if bridge is empty (without set up bridge ports) bridge will have max possible mtu.

5

but bridge is not empty , 3 wlan is in bridge

6

is L2MTU shown only on RBs?.. I don’t see it on my x86…

7

http://wiki.mikrotik.com/wiki/Maximum_Transmission_Unit_on_RouterBoards#MAC.2FLayer-2.2FL2_MTU

L2MTU support is added for all Routerboard related Ethernet interfaces, VLANs, Bridge and VPLS interfaces ..
All other Ethernet interfaces might indicate L2MTU only if the chip set is the same as Routerboard Ethernets

8

thanks. will the support be extended?

9

wow! a bit smart spambot?.. coool =)

10

I have a problem relating to this L2MTU field that downed a bunch of my customer today (RB450). Come to find out that my ether1 is stuck with an L2MTU of 1526 and as soon as I move the ethernet cable and ip address to another port I can get through just fine.

The other ones are set to 1522, what is weird about this is that I can’t change this setting anywhere. or at least anywhere that I can find. The other thing that is strange is that I don’t believe I did anything to cause this, one second it was working and the next it wasn’t.

This happened around the time I created a vlan on ether1, I have since removed the vlan – first thing I did when I had to access the unit with a serial cable as my only way of getting into it.

Does anyone has any insight on this for me? Maybe I am just retarded…

11

L2MTU can be changed from terminal only.

12

Nevermind - I am retarded all of the other Mikrotik’s I have are the same, there must be some other explanation for what happened.

Regards,

Matt

13

Helo All,

Why my RouterOS can’t view L2 MTU??
no-L2MTU~.jpg

14

because hardware/driver doesn’t support that