US Patent 9276689 Pluggable packet master clock

Apparatus for providing timing information, the apparatus comprising: a primary reference time clock (PRTC) that provides a reference time of day (ToD) and a reference frequency; a packet master clock that receives the ToD and reference frequency and is configured to distribute timing to a slave clock in accordance with a timing over packet procedure responsive to the ToD and the reference frequency; and a housing that houses the PRTC and packet master clock which may be plugged into a conventional small form factor (SFP) compliant cage to connect the packet master clock to a packet switched network (PSN).