We are already running /22 on other hardware, but not owned by us, and now migrating router to own, it's mikrotik.
There are already customers there, each using his own ip, and yes 192.168.1.255, 192.168.2.0 - also routed and used. (In fact IPs are not 192.168.X.X, but for our case it doesn't matter). Now in test-mode mikrotik also connected to network, yes, via sfp-port interface.
add address=192.168.0.1/22 interface=sfp-sfpplus1 network=192.168.0.0
I've setup BGP instance, have 2 peers now, and 1-2 more will be in nearest future. And i need to announce 1x /22 and 2x /23 prefixes for same network.
/routing bgp instance
set default disabled=yes
add as=XXXXX client-to-client-reflection=no name=XXXXX out-filter=OUTFILTER redistribute-connected=yes \
/routing bgp network
add disabled=no network=192.168.0.0/22 synchronize=yes
add disabled=no network=126.96.36.199/23 synchronize=yes
add disabled=no network=192.168.2.0/23 synchronize=yes
Regarding explanation in wiki if sync enabled - i need to get exact match route in routing table for this network.
Regarding tested, in fact without it - bgp won't work properly at all, routing bgp peer resend-all will not work (bgp proccess would not generate packets peer X.X.X.X rcvd UPDATE about 192.168.0.0/23 -- withdrawn)
So to have properly running bgp announce and soft reconfiguration with my peers i need to have in routing table exact prefix match for /23. And the question - how to do it in proper way?
I cannot do like your stuff recommends - have smaller networks, and aggregate them to bigger prefix by the help of blackhole route. I have inverse case - i have a lot of networks directly connected to router interface, and i need for properl bgp working to have more specific routes, example: network directly connected /22 - so i need to announce /22 and 2x /23 in bgp, network is /23 - 1x /23 and 2x /24.
So in conclusion - i do not have a target to split directly connected network, i need to create somehow fake routes /23 to get it normally working with BGP and soft reconfiguration with BGP peers.