For 27th time since 1972, a leap second is confirmed for 2016. It will take place on December 31 and to ensure our customers have everything they need to know about this upcoming event, Cisco has published an Information Page on Cisco.com.

Similar to a leap year, the leap second helps bring our tracking of atomic time in line with the Earth’s actual rotation (astronomical time). The key difference is that a leap second is only scheduled when measurement of the earth’s rotation requires it. And the decision on whether to add one is made just six months ahead of the occurrence itself.

As the backbone of the networking industry, we are completely cognizant of the potential disruption this addition of a leap second has on modern computing equipment and devices. To mitigate this risk, a network assessment must be done. In some cases, software updates may be necessary to ensure technology can navigate the scheduled leap second.

There’s never a better time to ensure our technology and customers’ networks are ready. Like in 2008, 2012 and 2015, we’ve set up a cross-functional team at Cisco worked to assess potential impacts and deliver any necessary fixes. As a result, we don’t expect any of our customers to experience major impacts or outages.

Customers should start by checking the Product Information tab of Cisco’s leap second information page. This list details how Cisco products are expected to respond to the 2016 leap second. It also includes links to updates that will be needed for select devices, and a summary list of products with no expected impacts.

The December timing of the 2016 leap second may add some complexity for those companies that experience their busiest period from late November through December. Many companies avoid performing network maintenance during this period, so we recommend that they work to implement the necessary updates as soon as possible.

For technical questions, customers can contact their Cisco account representative or Cisco Technical Assistance Center (TAC).


Ravi Chandrasekaran

Senior Vice President

Enterprise Networking