A framer is a device, system or an IC solution that is used to process frames in data networking. It is widely used in SONET synchronous data transmission on optical media. A framer provides frame alignment as its first activity when the data is received. Once the start of the frame is known, the section and the line overheads are then extracted. A framer usually has two paths that are independent of each other; one for data reception and the other for data transmission. It provides pointer processing in a downstream direction. It also provides pointer interpolation in an upstream direction.

In buying a framer device, one thing to consider first is the application. Different applications need a specific framer device. Some commonly supported applications are edge and WAN ATM switches, IP routers, packet switches and hubs, and for applications involving multi-protocol switches. The second thing to consider is the supported interfaces. Today’s framer device has several supported industry standard interfaces.

A framer device comes with a variety of features. Some of the important features to look for in buying this device are the supported industry standard interfaces, the number of buses, the size of the bus, and the operating frequency. Different applications may need a different interface, and this is important so that the framer can communicate with other devices. The number of buses is important in parallel interfacing. The size of the bus is specified in terms of bit. Larger bus width supports faster transmission. Some framer solutions nowadays can support industry standard serial and parallel interfaces with four 8-bit buses running at around 20 MHz.