Paint a DB Link = for example in a network there programs which auto discover, mapping and paint all the network by SNMP. I want to know if there any tool which do something like this, "auto discover and paint" the db liniks over de databases of my network.
A database link is really nothing more than a connection definition stored in a database. It is only used when a query runs that accesses an object in the remote database.
As such, I know of no way to dynamically map database links. The best you can do is visit all of your databases and document the db_links that exist there. You can then manually create an overlay to put on top of your network topology map.
As an added layer of complexity, you must realize that the db_link definition actually points to an entry in the local tnsnames.ora file. So the entry in the tnsnames.ora file determines which actual database the link points to. For instance, in a dev database, the dblink will be called to PRODDB2. However, we don't really want to point a dev database to a production database, so the PRODDB2 entry in the tnsnames file will point to DEVDB2. We do this so the code that uses the database link does not have to change as it moves from dev to QA to production. The point being, you can't just look at the database link definition in the database, you have use tnsnames.ora to verify where that link is pointing.