MTU error creating Vlan over Bond

RouterOS Virtualization
1

Hi!!

I’ve been trying to test in GNS3 inter-vlan routing with Router-On-A-Stick over a Bonding interface before deploying to a CCR1009-7G-1C-1S+.

Something is not working, but just in virtualized environments.

The commands I’m testing are just two:

/interface bonding add name=bond mode=802.3ad transmit-hash-policy=layer-2-and-3 slaves=ether2,ether3
/interface vlan add name=vlan10 vlan-id=10 interface=bond

It DOES work in real hardware with version 6.42.12.

It does NOT work in virtualized scenario, throwing error

failure: could not set mtu

I’ve tried this in Virtualbox and in GNS3(qemu) with the same error.

I’ve also tested newer versions in GNS3(6.45 and even 7beta) with same error.

In Internet there are videos showing the same commands I use working in GNS3, so i’ve downloaded an older version (6.34.6) and the commands work ok in GNS3.

Does anyone have a hint about where to look?

Thanks

2

I am also experiencing this error.

Any updates?

3

No. But I’ve reduced the MTU and is working.

4

Thanks for the reply.
I’ve been trying all the other previous long-term releases and nothing worked.
I will try decreasing the MTU too and see how it goes.

5

So after a lot of trial and error, I finally managed to add a vlan in my GNS3 virtual router using the following commands below:

***Create the Main Bridge

/interface bridge add name=mainbridge
/interface bridge print

Notice that the l2mtu=65535

***Bond the interfaces

/interface bonding add mode=802.3ad transmit-hash-policy=layer-2-and-3 name=bond slaves=ether9,ether10

***Add the Bonded Interfaces to the Main Bridge

/interface bridge port add bridge=mainbridge interface=bond
/interface bridge print

Now the l2mtu=1500

In order to add a vlan, you need to specify the mtu of the vlan. The next highest value that is accepted is 1496.

***Create a VLAN

/interface vlan add interface=bond name=vlan10 vlan-id=10 mtu=1496

Do remember that this command is only necessary when in GNS3.

Cheers!

6

The same for me 1496 was the maximum MTU without error. Everything works as expected. Don’t know why!!
Without using a bridge I had also to reduce MTU to 1496.

7

Do you know which was the root cause of this issue? I’m trying to replicate a real scenario on Mikrotik CHR with GNS3, the default 1500 mtu isn’t working. Thanks!