e quickly measured against the test device (more in "Chapter 12. Operating and Verifying Timing Solutions", on test equipment). One could do something similar by measuring the frequency of an Ethernet port configured with SyncE, but that introduces security issues because it requires someone to configure an active port to measure it. The BITS port is currently being phased out on devices from most vendors. There are several reas- ons for this: Real estate (space) constraints on the front panel means that hardware engineers want to remove it and use the space saved for something else (like more Ethernet ports). The electronics industry that produces components is removing the products (such as framers) needed to build BITS interfaces. There are several reasons for this, including low volumes and expensive production processes to manufacture them. Router vendors are seeing less demand for BITS interfaces in customer requests, and the higher cost of the components to make them leads to a price disadvantage compared to routers from other vendors. The BITS port is quickly becoming a legacy device, SO do not assume that they are always present, especially on smaller platforms where faceplate space is at a premium and device cost is a constant consideration. The alternative is to use a 10-MHz interface (which may also support 2 MHz, but not E1/T1). Frequency Inputs and Outputs (SyncE) Devices such as a PRC/PRS that provide a reference frequency are increasingly also equipped with an Ethernet port (as well as the commonly available 10 MHz). Any modern PRTC delivering phase is almost certainly Ethernet enabled with support for SyncE output. This means that one of the best sources of frequency for a device is to use SyncE, mainly because it is simply Ethernet. There are several conditions that you must ensure are met to confirm a node correctly supports SyncE. Generally, fiber Ethernet interfaces can be designed to support SyncE without too much is- sue. Of course, the device should state in its documentation that it suppo