Ver.3.x of Mikrotik RouterOS has the checkbox "Synchronize ".

routing bgp network print I didn't found any information in the Manual. For what it is necessary?

Short answer, stay away from it. It's evil

For a long answer on what syncronization is:
http://www.juniper.net/techpubs/softwar ... fig11.html

(yehe I know it's for juniper, but it applies for anything that talks bgp)

HI:
If you Enable Synchronize in Networks BGP, by default network is advertised only if corresponding route is present in routing table else (if it`s Disabled) you can advertised every subnets even if corresponding route is NOT present in your routing table.

It also "synchronizes" the route attribute.

Example And you enable synchronize, the community 123:456 will be announced, too

Short answer, stay away from it. It's evil

This is completely wrong IMO/

TLDR: Standard BGP behavior is to announce networks based on their reachability in the active routing table. Best practice is to create static null routes to nail up your advertisements if you need to do so.

Network statements are commands that instruct the BGP process to originate prefixes, and synchronize means the router should only originate those prefixes which is has matching IP routes. In other words, don't hoist the flag and announce a prefix unless you actually know how to get there. This is the default behavior in other vendors' implementations. Best practice for a small network where you have only one border router, for instance, would be to create a static null route (type=blackhole in Mikrotik-speak) for your destination. This is a "nail-up" route. This may seem nit-picky in the beginning, but I've had several instances over the course of my career where I didn't think something was important best-practice-wise, and I just did whatever worked, and later had to face challenges based on my non-standard configurations.