A Port For BCM

Typically SQL Server installs create a sql instance and setup an NT service that listens for connections on a UDP port. A bug in the rcp port mapper was the cause of a huge worm attack on the internet a few years. It exploited the fact that sql listened on that UDP port on millions of machines. When a sqlserver.exe instance service starts up, it picks a random, unused, TCP port for connections. It then tells the sql listener what TCP port it is using.

When a typical client machine tries to connect a sql instance on a server, the sql client software calls the sql listener UDP port and requests connection to a sql instance. The sql listener then checks its table of instances that have published to it. If it finds a match, it looks up the TCP post number of the instance, and then returns the TCP port number to the client. The client then connects through that TCP port directly to the server.

When BCM installs MSDE it specifies a fixed TCP port, 56183, for the instance, and that information is kept a secret from the sql UDP listener. The only way to connect a BCM client to a BCM database on the server is to use TCP port 56183.

By the way, the port number is different for BCM v3 Beta; 5356. It complicates things a bit, but it allows BCM v2 (MSDE) and BCM v3 (Sql Xpress) databases to exist on the same machine.

Therefore, if you move the BCM database from the original MSDE instance to a SQL Server instance, BCM clients will only connect to the database if the SQL Server instance is using TCP port 56183.