ROBUST DISTRIBUTION OF IP TIMING SIGNALS

Number: 20210028876
Published: 2021-01-28
Filed: 2019-07-22
Assignee: Disney Enterprises, Inc.
Inventors: Beardsley; Craig L., Liscano; Jerome G., Strein; Michael J., Brown; Carl A., Shah; Nishith, Kepler; Benjamin H.
CPC: H04J3/0641; H04Q11/0005; H04J3/0673; H04N21/6125; H04J3/0667; H04N21/4305; H04N21/64322
Verdict: Set aside broadcast infrastructure timing, plumbing
Source: Google Patents · FreePatentsOnline

Abstract

Embodiments disclosed herein provide techniques to selectively distribute Precision Time Protocol (PTP) data in a network. The network can include multiple different network devices (e.g., switches) connected to form a network architecture (e.g., a spine/leaf architecture). Rather than distributing the PTP data (e.g., PTP timestamps) through all the network devices in order to synchronize local clocks to a global, master clock, the embodiments herein describe an out-of-band distribution network which selectively distributes the PTP data to select network devices in the network.

Background

BACKGROUND Field of the Disclosure

Embodiments disclosed herein relate to selectively distributing Precision Time Protocol (PTP) time reference data in network. Description of the Related Art

The Precision Time Protocol (PTP) is defined by the Institute of Electrical and Electronics Engineers (IEEE(r)) 1588 standard and adopted by the Society of Motion Picture and Television Engineers(r) (SMPTE(r)) 2059. The PTP standard provides a timestamp that has 80 bits of precision and is accurate to the microsecond range. Generally, SMPTE 2059 is directed to leveraging PTP to provide timestamps for video data that is encapsulated in Internet Protocol (IP) packets. Using these protocols, PTP time reference data can be shared throughout a network to provide a synchronized clock to media nodes (e.g., cameras, audio devices, video encoders, audio encoders, etc.) connected to the network. That is, the switches and other network devices distribute clock signals (e.g., timestamps) that can synchronize local clocks to a master clock.

However, every hop in the network introduces inaccuracy into the PTP signals. That is, even when the switches in the network are PTP-enabled, the switches introduce jitter (e.g., 5-20 nanoseconds) which can reduce the accuracy between a local clock and the master clock. Further, if a path in the network traverses a non-PTP-enabled switch, the jitter or inaccuracy in the PTP signals is increased more, since the non-PTP switch does not account for the

Claims

1. A network, comprising: a plurality of Precision Time Protocol (PTP)-enabled network devices communicatively coupled to a plurality of media nodes; a plurality of non-PTP enabled network devices communicatively coupled to the plurality of PTP-enabled network devices; an out-of-band PTP distribution network communicatively coupled to the plurality of PTP-enabled network devices, the out-of-band PTP distribution network comprising: a master clock device configured to generate a master clock, and a transparent clock switch, wherein the transparent clock switch is communicatively coupled between the master clock device and the plurality of PTP-enabled network devices, wherein the transparent clock switch measures a transit delay, and inserts the transit delay, into PTP packets exchanged between the master clock device and the plurality of PTP-enabled network devices, wherein the plurality of PTP-enabled network devices is configured to transmit only non-PTP signals to the plurality of non-PTP enabled network devices. || 8. A method for synchronizing boundary clocks in a plurality of PTP-enabled network devices, comprising: receiving, at the plurality PTP-enabled network devices, an announcement from a master clock device, wherein the announcement is received via a transparent clock switch, wherein the master clock device and the transparent clock switch form an out-of-band PTP distribution network; synchronizing the boundary clocks to a master clock generated by the master clock device based on a timestamp of the master clock and a transit delay corresponding to the transparent clock switch; transmitting timestamps of the boundary clocks to media nodes connected to the plurality of PTP-enabled network devices; and transmitting non-PTP data signals from the plurality of PTP-enabled network devices to a plurality of non-PTP enabled network devices. || 15. An out-of-band distribution network, comprising: a PTP-enabled network device; a master clock device configured to generate a master clock, and a transparent clock switch communicatively coupled between the master clock device and the PTP-enabled network device, wherein the transparent clock switch measures a transit delay, and inserts the transit delay, into PTP packets exchanged between the master clock device and the PTP-enabled network device, wherein the PTP-enabled network device is communicatively coupled to a non-PTP enabled network device.