John Carbone, Express Logic
embedded.com (December 29, 2013)
In today's world of connected devices, smartphones upload photos to servers in the cloud, car rental agencies check-in your rental upon your return, you can purchase in-flight meals using your credit card, and doctors access vital signs of patients across town—or around the world.
While such machine-to-machine (M2M) communication is performed over the Internet and generally uses the popular transmission control protocol (TCP), what you may not realize is that many other M2M communications utilize ‘user datagram protocol’ (UDP) and communicate at rates that would be unachievable using TCP.
In fact, UDP can be advantageous for many embedded M2M system requirements, and might be worth consideration for your next “Internet of Things” design. Following are highlights and some of my thoughts on the use of UDP in M2M communications.
TCP/IP is a layered protocol, which means more complex protocols are built on top of simpler underlying protocols (Table 1). In TCP/IP, the lowest layer protocol is at the link level and is handled by the network driver. This level is typically targeted for Ethernet, but it could also be fiber, serial, or virtually any physical media.
On top of the link layer is the network layer. In TCP/ IP, this is the IP, which is responsible for sending and receiving simple packets, in a best effort manner, across the network. Management type protocols like ICMP and IGMP also are typically categorized as network layers, even though they rely on IP for sending and receiving.
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