I have a situation where I need to set the MTU when I advertise IPv6 addresses from my Mikrotik Router. My goal is to have all devices that receive an IPv6 address from the router advertisements have the MTU for their IPv6 connection set to 1420. Is that possible?
My situation is that this particular site connects to the internet2 first through a L2TP tunnel, and then through a 6to4 tunnel. The L2TP tunnel has a MTU limit of 1420. Packets that pass through both tunnels sometimes fail to load specific web pages unless the web server itself has an MTU equal to or less than 1420. I can manually set a computer or network device MTU to allow traffic, but ideally I’d like all current and future devices to have their IPv6 MTU set automatically.
Can RouterOS do what I need? What config do I need to accomplish this setup?
I tried “add mtu=1420” but I get the error “failure: configuration for this interface already exists”
I tried “set mtu=1420” and it comes up with a prompt “numbers:” If I leave the prompt blank, it accepts the command but doesn’t appear to make any config changes. I tried putting in 1420 on the number, but it gives the error: “Script Error: action cancelled”.
When I export the config for ipv6 / ND there is no current configuration.
What syntax do I use to set the mtu for advertisements?
You should try WinBox, the greatest admin interface ever made.
But of course command line can be used too. First do “/ipv6 nd print” and it will list all items and their numbers (there can be different configurations for different interfaces), in your case probably just default one with number 0. Then you can do “/ipv6 nd set mtu=1480”.
Thank you for letting me know you can set the MTU in winbox. Based on the manual, I thought this was one of those settings that was command line only. I found the setting, and it works now.