Cisco Nexus GM Time Synchronization NIC Data Sheet

Data Sheet

Available Languages

Download Options

  • PDF
    (324.1 KB)
    View with Adobe Reader on a variety of devices
Updated:July 9, 2021

Bias-Free Language

The documentation set for this product strives to use bias-free language. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. Learn more about how Cisco is using Inclusive Language.

Available Languages

Download Options

  • PDF
    (324.1 KB)
    View with Adobe Reader on a variety of devices
Updated:July 9, 2021


Dual port IEEE PTP GM Time Synchronization solution

High-performance GPS-based PTP GM in a half-height NIC form factor

The Cisco Nexus® Cisco Nexus GM Time Synchronization NIC is a unique grandmaster solution. It packages an entire GPS-based Precision Time Protocol (PTP) grandmaster into a tiny, half-height, half-length network-card form factor. This allows users to save on rack space without compromising on features. The onboard GPS receiver provides time synchronization to a UTC of 60ns. The adapter also provides PPS and 10MHz output and can be used to synchronize the host-system clock to the GPS reference.

High-stability holdover

An onboard high-stability oscillator results in a holdover of better than 15us over 24 hours.

During times when GPS reception has failed, the Cisco Nexus GM Time Synchronization NIC will automatically revert to using its onboard high-precision OCXO oscillator as a holdover time reference until the GPS lock is restored. For applications demanding exceptional holdover accuracy, a miniature atomic clock upgrade is also available.

Simple yet powerful

The software included runs on your host, allowing the GM to run as an “appliance.”

The Cisco Nexus GM Time Synchronization NIC is bundled with open-source configuration and management software. The included software runs on any Linux host. This allows users to set the operating conditions for the Cisco Nexus NIC GM; the adapter can also be used to show running status information (for example, the number of connected slaves, the GPS lock, the number of satellites in view, etc.).

Despite using host-based configuration tools, the Cisco Nexus GM Time Synchronization NIC handles all PTP operations internally. This eliminates any need for the host at runtime. The Cisco Nexus GM Time Synchronization NIC will power-up and immediately begin serving time using the last saved configuration, even if the host operating system fails to start. This ensures always on operation, even under host-failure conditions.

GPS-locked packet capture and timestamping

Built-in timestamping records frame arrivals, using a GPS-disciplined clock, to a granularity of 4ns.

These timestamps are available through a direct access API (libexanic), through a transparent TCP/UDP acceleration library (exasock), and to the kernel. Standard utilities such as tcpdump can make use of these hardware timestamps. You can also acquire our open-source high rate capture application called Exact Capture for demanding capture requirements.

Cisco Nexus GM Time Synchronization NIC

Figure 1.               

Cisco Nexus GM Time Synchronization NIC

IEEE 1588v2 GM

     2x SFP+ ports

     Hardware accelerated PTP Grandmaster (Port 0 only)

     Each port configurable to 10G, 1G or 100M

     IPv4 and PTP Ethertype operation

     Unicast and multicast operation

     Up to 128 unicast slaves

     Telecom profile

     Default profile

GNSS receiver

     GPS, GLONASS, QZSS, and BeiDou

     72 channels

     Internal timesync accuracy: 30ns RMS

     Receiver sensitivity: 167dBm

     Active antenna support (3.3V)

     Cold-start acquisition <30s

     Tunable antenna delay

High-precision oscillator


     24 hour holdover, <15us

     0.2ppb temperature stability

     Allen variance: 1 x10-11


     1 PPS @ 3.3V

     10MHz @ 3.3V

     Can be configured for PPS in


Form factor:

     Low-profile PCI Express Card

     150x68mm (5.91x2.67in)


     Operating temperature: 0 °C to 55 °C

     Storage temperature: -40 °C to 70 °C

     Operating Relative Humidity: 5% to 90% (non-condensing)

     Storage Relative Humidity: 5% to 95% (non-condensing)


     2x SFP+

     SMA for GPS Antenna Connector

     SMA for PPS in/out

Data rates:

     10GbE, 1GbE, 100M Fast Ethernet

Supported media:

     Fiber (10GBASE-SR, 10GBASE-LR, 1000BASE-SX), SFP+ Direct Attach

Host interface:

     PCIe x8 Gen 3 @ 8.0 GT/s per lane

Operating systems:

     Linux x86_64 (all distributions)


Timestamp resolution:

     4 ns

Timestamp availability:

     All received frames, most recent transmitted frame

Cisco environmental sustainability

Information about Cisco’s environmental sustainability policies and initiatives for our products, solutions, operations, and extended operations or supply chain is provided in the “Environment Sustainability” section of Cisco’s Corporate Social Responsibility (CSR) Report.

Reference links to information about key environmental sustainability topics (mentioned in the “Environment Sustainability” section of the CSR Report) are provided in the following table:

Sustainability topic


Information on product material content laws and regulations


Information on electronic waste laws and regulations, including products, batteries, and packaging

WEEE compliance

Cisco makes the packaging data available for informational purposes only. It may not reflect the most current legal developments, and Cisco does not represent, warrant, or guarantee that it is complete, accurate, or up to date. This information is subject to change without notice.

Cisco Capital

Flexible payment solutions to help you achieve your objectives

Cisco Capital® makes it easier to get the right technology to achieve your objectives, enable business transformation and help you stay competitive. We can help you reduce the total cost of ownership, conserve capital, and accelerate growth. In more than 100 countries, our flexible payment solutions can help you acquire hardware, software, services and complementary third-party equipment in easy, predictable payments. Learn more.




Learn more