Physical layer processing of timestamps and MAC security

A physical layer device provides both timestamp processing and security processing. The timestamp processing may be PTP processing according to IEEE Std. 1588 and/or OAM processing according to ITU-T Recommendation Y.1731. The security processing may be MACsec processing according to IEEE Std. 802.1AE. The timestamp processing may delay some packets to avoid impairing accuracy of timing information. For example, the accuracy of timing information could be impaired when a packet containing the timing information is delay due to additional bits added to a preceding packet to include a security tag and integrity check value.