Our earth is very slowly slowing down, which means every now and then scientists call to add an extra second to our time to compensate. The last was in 2012, the next one is coming up on June 30, 2015 23:59:60 UTC. For more information about this leap second, check timeanddate.com.

Cisco posted an impact analysis on their website with links to bug reports which determine the impact. While most campus products are unaffected, there are some warnings on datacenter products where the leap second update can lead to a crash or lockup.

My intention is not to scare, but to have this post serve as a notice to check whether something in your environment may be affected. Cisco uses a lot of ‘may crash’ and ‘may lockup’ in the bug reports, so my understanding is that it is not a guarantee that it will happen, just that there is a chance. But I’d rather not take that chance. 😉

Below is a summary of the datacenter products, but for the full product list check the Cisco website.

 

Product Impact Workaround Cisco Bug
Nexus 1000v Possible active VSM reset Disable NTP config CSCus80369
MDS 9000 Series
MDS 9513
MDS 9509
MDS 9506
MDS 9222i
MDS 9148
MDS 8-Gb Fabric Switch for HP c-Class Blade System
MDS 9134
MDS 9124
MDS 4-Gbps Fabric Switch for HP c-Class BladeSystem
MDS 4-Gbps Fabric Switch for IBM BladeCenter
Switch doesn’t understand leap second Non-disruptively resync time CSCut22182
Nexus 3000 Series If PTP is enabled, a skew of max 35 seconds can be observed Disable PTP, increase TTL or upgrade to a known fix. CSCui37256
Nexus 5010/5500 Series Switches running NX-OS 5.0, 5.1 5.2 may lock up. Disable NTP config or upgrade to a known fix. CSCub38654
Nexus 5010/5500 Series If PTP is enabled, a skew of max 35 seconds can be observed Disable PTP, increase TTL or upgrade to a known fix. CSCut81357
Nexus 6000 Series Switches running NX-OS 5.0, 5.1 5.2 may lock up. Disable NTP config or upgrade to a known fix. CSCub38654
Nexus 7000 (SUP 1 only) Affected NX-OS versions may experience a livelock. Disable NTP config or upgrade to a known fix. CSCua77416
Nexus 9000 Series If PTP is enabled, a skew of max 35 seconds can be observed Disable PTP, increase TTL or upgrade to a known fix. CSCut78541
Unified Computing System (UCS) Manager
Unified Computing System (UCS) Fabric Interconnect
Unified Computing System (UCS) C-Series Rack Mount UCS-Managed Server SW
System could crash causing a network outage. Versions 2.0 & 2.1 are unaffected. Disable NTP config or upgrade to a known fix. CSCus83447


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