Industrial automation and control, utilities, and military networks require large numbers of devices in their networks to have an accurate and synchronized view of time. Cisco Industrial Ethernet switches are capable of accurate time distribution using PTP or IRIG-B, but previously relied on an external source (Grand Master Clock) to provide accurate time. The IE 5000 switch has a built-in Global Navigation Satellite System (GNSS) receiver that enables the switch to determine its own location and get an accurate time from a satellite constellation. The switch can then become the source (Grand Master Clock) for time distribution in the network. GNSS capability simplifies network synchronization planning and provides flexibility and resilience in resolving network synchronization issues in a hierarchical network.

GNSS Hardware

The IE 5000 uses a GNSS receiver with precise frequency and phase outputs for the host system. When connected to an external GNSS antenna, the receiver contains all the circuitry necessary to automatically acquire GNSS satellite signals, track up to 32 GNSS satellites, and compute location, speed, heading, and time. It provides an accurate one pulse-per-second (PPS) and stable 10 MHz frequency output. For more information, see GNSS Signaling

The GNSS chip supports the following frequency bands:

• GPS/NAVSTAR - Global Positioning System – USA: L1

• GLONASS – Global'naya Navigatsionnaya Sputnikovaya Sistema – Russia: L1/G1

• BeiDou – China: (including B1-2)

Note	The Galileo satellite system is not currently supported in the released software.

• GNSS is supported only on IE 5000 switches with SKUs that have Version ID (VID) v05 or later. The show version command output includes the VID:

  Switch# show version
  .
  .
  .
  Version ID : V05

• The GNSS feature is supported only on IE 5000 switches that have GNSS receiver firmware version 1.04 or later. To verify the GNSS firmware version, use the show version command:

  Switch# show version
  .
  .
  .
  GNSS firmware version : 1.04

• A GNSS license is not required. The GNSS feature is available for all feature sets (lanbase, ipservices).

• GNSS is available as a timing source for PTP default and power profiles only.

• GNSS is available as a timing source for PTP only when PTP is in GMC-BC mode.

• Syslog messages are sent when the following GNSS events occur:

  • GNSS is in self-survey mode.

  • GNSS reaches OD mode.

  • GNSS firmware upgrade is in progress, complete, or failed.

• If the switch is the PTP grandmaster clock and it loses the antenna signal, the clock quality will degrade, resulting in a grandmaster clock switchover.

• The GPS antenna alarm will not trigger an external relay alarm.

GNSS is disabled by default.

The following shows example output for show gnss status after the GNSS receiver has completed self-survey mode and is providing timing information from the satellite system:

# show gnss status
 GNSS status: Enable
 Constellation: GPS
 Receiver Status: OD
 Survey progress: 100
 Satellite count: 7
 PDOP: 1.00    TDOP: 1.00
 HDOP: 0.00    VDOP: 0.00
 Alarm: None

Status fields and possible values are:

• GNSS status

  • Enable

  • Disable

• Receiver Status

  • Auto—Auto mode for 2D/3D

  • 1SV—Single satellite

  • 2SV—Horizontal (2D)

  • 3SV—Full position (3D)

  • OD—Over-determined

• Survey progress—This field shows the progress of the survey as a percentage of fixes collected so far. The self-survey is complete when the self-survey progress reaches 100%.

• PDOP—Position dilution of precision

• HDOP—Horizontal dilution of precision

• VDOP—Vertical dilution of precision

• TDOP—Time dilution of precision

• Alarm

  • Antenna open

  • Antenna shorted

  • Not tracking satellites

  • Survey-in progress

  • No stored position

  • Leap second pending

  Note	If any GPS alarm conditions are present, the switch may not be providing timing information from the satellite system. The alarm will clear automatically.

The following shows example output for show gnss satellite :

Switch# show gnss satellite all
SV Type Codes: 0 - GPS, 1 - GLONASS, 2 - Beidou

All Satellites Info:
SV PRN No   Channel No       Acq Flg    Ephemeris Flg     SV Type     Sig Strength
----------------------------------------------------------------------------------
        5            0             1                1           0               44
        2            1             1                1           0               46
       29            2             1                1           0               49
       18            3             1                1           0               43
       25            4             1                1           0               44
       21            5             1                1           0               44
       20            6             1                1           0               45
       12            7             1                1           0               47
       15            8             1                1           0               47
       13            9             1                1           0               46

This example shows output for show gnnss time and show gnss location :

Switch# show gnss time
Current GNSS Time:
Time: 2017/09/18  19:29:58 UTC Offset: 18

Switch# show gnss location
Current GNSS Location:
  LOC: 30:26.045678699 N  97:45.036946399 W  266.1928 m

• Cisco Industrial Ethernet 5000 Series Switches

• Cisco IE 5000 Hardened Aggregator Hardware Installation Guide

• Precision Time Protocol Software Configuration Guide for IE 4000, IE 4010, and IE 5000 Switches