MikroTik

Is there a way to do a conditional BGP advertisement in routeros? Here is my situation. I have 2 connections, a big pipe and a small pipe. The provider I get the small pipe from buys transit from some of the big tier 1s. They propogate my route advertisement to these tier 1 isps who then preference that route over the advertisement via my other provider, who is a tier 1 and has peering with them. We have tried as path prepending, community strings, etc and haven't had any luck. I only want inbound traffic via the small pipe if the big pipe is down. On a cisco router I can accomplish this using a conditional advertisement using something like this:

neighbor 10.10.10.1 advertise-map ADVERTISE non-exist-map NON-EXIST

is there any way to do something like this with mikrotik?

Thanks!
cotcomsol

in RouterOS you will not find similar feature, however to achieve your goal, you can set routing filters to reject the prefix going to one peer. Then write a script that will check if second peer running, if not - disable filter rule.

another idea might be to use local-pref with your providers ?

thanks for the suggestions. we have tried local-pref but haven't achieved what we are looking for. I will try writing a script to enable/disable the advertisement.

An easier way is to do an asymmetrical announcement of your prefixes

announce your full prefixes to both peers ( IE: 10.10.222.0/23 )
then announce smaller prefixes of the same subnet to the preferred peer (IE: 10.10.222.0/24 and 10.10.223.0/24 )
this way the more focused prefix is always choosen by remote ASs.
If your main link goes down, the second peer still announces the routes to your network.


That's how i do load balancing, in a very basic way.
I apologize for my english.