+------+              +------+
               | ISP1 |              | ISP2 |
               +---+--+              +--+---+     
                   |                    |     Service Providers
       ............|....................|.......................
                   +---------++---------+     Enterprise Network           
                             ||     
                          +--++-+ 
                          | CPE | 
                          +-----+ 
                                ... (Internal Network)