Good Day,
I have an RB750GR3 (R1) that is currently functioning well as my home router. I also have a HAPac2 (R2) that, for various reasons, I’d like to replace it with. I’ve been looking into ways to just copy the config from one to the other and none seems to be a simple backup-restore kind of procedure so I’ve decided to just export the config from R1 and copy and paste large chunks of it to import into R2, cleaning up some clutter as I go. I’ve already completely flattened R2 by resetting it with the no-default-config option and have it up and running with a static IP on an unused port so I’m ready to go. My network setup is pretty simple, I have a modem in bridge-mode providing internet connectivity, it is connected to the WAN port (ether-1) on the router, which is connected via ether-2 to a Mikrotik switch, and everything on the home network is connected to the switch. All LAN ports are bridged. The first issue I’ve come across is the admin-mac option on the bridge. On R1 it looks like this:
/interface bridge
add admin-mac=XX:XX:XX:XX:XX:XX auto-mac=no comment=defconf name=LAN_Bridge \
port-cost-mode=short
Since R2 will be replacing R1 and is meant to be a plug-in replacement, would it be advisable to give it the same MAC for the bridge interface? I’d like to have as little disruption as possible to the home network when I swap the devices out and at no time will they both be plugged in with the same configurations, so there won’t be a conflict. But is it the advisable thing to do?
Thanks
Yes.
One of the actual issues with backup (not export and manually restored in snippets like you did) is that it “brings over” the old MAC and sometimes this is not advised because it can create conflicts, but in your case you are replacing the device and you never have the two devices connected at the same time.
The idea of the backup (and restore) is more like a “clone”, you have a device in operation, make a backup of it, when/if that device fails you get an exact same model device and restore to it the backup, then replace with it the failed one.
So backup would have worked for you, if the device was another RB750GR3 (and you would have had the cloned MAC address), since the ac2 is a different device backup and restore may (or it may not ) have work, you did the right thing exporting and re-importing manually the snippets, better be safe than sorry.
Exactly what I needed, thank you. As a corollary, I guess I should also mirror the MAC addresses of the Ether-2-5 ports from R1 to R2? Ether-2 was the MAC that was used for the bridge on R1 and is currently the only one in use.
Cheers!
Yes and no.
In the sense that the way Mikrotik sets the MAC of the bridge is during the running of the default configuration script, and it does so by assigning to the bridge (and setting auto-mac=no) the MAC of the first interface it finds among the ports in bridge.
So, since:
- the default configuration puts ether1 self standing and ether2-5 into a bridge
- the interfaces are added in the order ether2, 3, 4 and 5
the net effect is that the automatically assigned MAC of the bridge is the same of that of ether2, and the reason why it is “forced” is to avoid that with auto-mac=yes it could change when the user removes/adds or however fiddles with ports on the bridge, and that is the main reason I believe why assigning a MAC and setting auto-mac=no is recommended for the bridge.
The risk of a duplication (only possible when/if you take ether2 out of the bridge) is lower than having the bridge MAC changed inadvertently, though there are diverging opinions on whether forcing manually on the bridge yet another MAC (different from all the ones given to the ether and other “self-standing” interfaces) is a good idea or in practice an unneeded precaution, JFYI:
http://forum.mikrotik.com/t/doubts-on-mac-address-on-bridge-uniqueness-laa-etc/182230/1
There is not written anywhere that the bridge MAC must be one of the ether ports in it, it could be a completely different one.