If a router interface is enabled for encryption and Layer 3 1588v2 packets are sent, they are encrypted using NGE. This means that if port timestamping is enabled on a router interface with NGE, the port timestamp is applied to the Layer 3 1588v2 packet using software-based timestamping instead of hardware-based timestamping, and consequently, timing accuracy may degrade. The exact level of timing or synchronization degradation is dependent on many factors, and testing is recommended to measure any impact.
If there is a need to support Layer 3 1588v2 with better accuracy for frequency or better time using port timestamping, an NGE exception ACL is required to keep the Layer 3 1588v2 packets in clear text. The exception ACL must enable UDP packets with destination port 319 to be sent in clear text.