|  | 11.6 | Other Network Layer Services
| 11.6.4 | IP and the transport layer
IP is a connectionless system; it treats each packet independently. For example, if you use an FTP program to download a file, IP does not send the file in one long stream of data. It treats each packet independently. Each packet can travel different paths. Some may even get lost. IP relies on the transport layer protocol to determine whether packets have been lost, and to request retransmission. The transport layer is also responsible for reordering the packets.