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).
1. Apparatus for providing timing information, the apparatus comprising:
a primary reference time clock (PRTC) that is operable to provide 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 the packet master clock, the housing being suitable for plugging into a conventional small form factor (SFP) compliant cage to connect the packet master clock to a packet switched network (PSN).
2. Apparatus according to claim 1 wherein the PRTC comprises:
a global satellite navigation system (GNSS) receiver that receives GNSS transmissions transmitted by GNSS satellites; and
a GNSS processor that processes received GNSS transmissions to generate the reference frequency.
3. Apparatus according to claim 1 wherein the PRTC comprises an internal oscillator that generates the reference frequency.
4. Apparatus according to claim 1 wherein the PRTC comprises an input for receiving the reference frequency from an external frequency source.
5. Apparatus according to claim 4 wherein the PRTC comprises a clock extractor that generates the reference frequency responsive to a physical data rate of a backplane of a network element of the SFP comprising the SFP cage into which it the apparatus is plugged.
6. Apparatus according to claim 1 wherein the PRTC comprises:
a global satellite navigation system (GNSS) receiver that receives GNSS transmissions transmitted by GNSS satellites; and
a GNSS processor that processes received GNSS transmissions to generate the ToD.
7. Apparatus according to claim 1 wherein the PRTC comprises an input for receiving the reference ToD from an external source.
8. Apparatus according to claim 1 wherein the PRTC comprises a frequency selector that receives a plurality of prospective reference frequencies and selects the reference frequency from the plurality of prospective reference frequencies.
9. Apparatus according to claim 8 wherein the PRTC comprises:
a global satellite navigation system (GNSS) receiver that receives GNSS transmissions transmitted by GNSS satellites; and
a GNSS processor that processes received GNSS transmissions to generate a prospective reference frequency of the plurality of reference frequencies.
10. Apparatus according to claim 8 wherein the PRTC comprises an internal oscillator that generates a prospective reference frequency of the plurality of reference frequencies.
11. Apparatus according to claim 8 wherein the PRTC comprises an input for receiving a prospective reference frequency of the plurality of reference frequencies from an external frequency source.
12. Apparatus according to claim 8 wherein the PRTC comprises a clock extractor that generates a prospective reference frequency of the plurality of reference frequencies responsive to a physical data rate of a backplane of a network element of the SFP comprising the SFP cage into which it the apparatus is plugged.
13. Apparatus according to claim 1 wherein the PRTC comprises a ToD selector that selects a reference ToD from amongst a plurality of prospective reference ToDs.
14. Apparatus according to claim 13 wherein the PRTC comprises:
a global satellite navigation system (GNSS) receiver that receives GNSS transmissions transmitted by GNSS satellites; and
a GNSS processor that processes received GNSS transmissions to generate a prospective reference ToD of the plurality of reference ToDs.
15. Apparatus according to claim 13 wherein the PRTC comprises an input for receiving a prospective reference ToD from an external source.
16. Apparatus according to claim 1 wherein the timing over packet procedure conforms to IEEE-1588-2008.
17. Apparatus according to claim 1 wherein the timing over packet procedure conforms with Network Time Protocol (NTP).
18. The apparatus according to claim 1 , wherein the conventional SFP-compliant cage for which the housing is suitable for plugging into is a cage configured to receive a module selected from the group consisting of: a Small Form-factor Pluggable (SFP) module, an Enhanced Small Form-factor Pluggable (SFP+) module, a 10G Form-factor Pluggable (XFP) module, a 100G Form-factor Pluggable (CFP) module, and a Gigabit Interface Converter (GBIC) module.
19. A packet switched network (PSN) comprising a plurality of apparatuses for providing timing information, each apparatus comprising:
a primary reference time clock (PRTC) that is operable to provide 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 information 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 the packet master clock, the housing being suitable for plugging into a conventional small form factor (SFP) compliant cage to connect the packet master clock to a packet switched network (PSN).
20. A PSN according to claim 19 and comprising a slave clock that receives timing information distributed by a packet master clock comprised in an apparatus of the plurality of apparatuses.
21. A plurality of apparatuses for providing timing information, each apparatus comprising:
a primary reference time clock (PRTC) that is operable to provide 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 information 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 the packet master clock, the housing being suitable for plugging into a conventional small form factor (SFP) compliant cage to connect the packet master clock to a packet switched network (PSN);
wherein the PRTC of at least one apparatus from the plurality of apparatus has a substantially same reference ToD and reference frequency as the PRTC of at least another apparatus from the plurality of apparatuses.