BGP ID selection process
It is best practice to configure the BGP ID explicitly by using protocols bgp <asn> parameters router-id <id>. If explicitly assigned, then this is the BGP ID that should be used. If it is not assigned explicitly, then the system choose one automatically. If a loopback address is configured as is not 127.0.0.1, it be used. If the loopback address is not used, then the largest IP address assigned to an interface in the system configuration be used.
So, best practice suggests that the following configuration commands be run on each BGP router to explicitly set the BGP ID. In this example, a loopback address of 10.0.0.11/32 is used.
Set the loopback address and prefix length (note the prefix length of 32). In this case 10.0.0.11/32.
Set the router ID to the previously defined loopback address.
Commit the configuration.
Verify the configuration.