Coexistence of IEEE 1588, C37.238 and 802.1AS, issues and recommendations

Abstract

Profiles and extensions of IEEE 1588 have recently been standardized as IEEE C37.238 (for electrical power systems) and IEEE 802.1AS (for audio-video bridging). The working groups focused more on innovation in their application domain than on keeping compatibility with the original default profile of IEEE 1588 J.4. As a result, the profiles cannot share the same network infrastructure, hampering the engineering of mixed system, e.g. integrated power and automation networks. Nodes that support several profiles become complex and have to support three MIBs for SNMP, while one would be sufficient. This position paper presents the peculiarities of IEEE C37.238 and IEEE 802.1AS and makes propositions to ensure at least coexistence on the same network, and possibly allow a reuse of a common trunk with compatible extensions. These propositions imply that all standards should be amended simultaneously at their next revision, with 1588v3 taking over the bulk of the additional features and the other becoming true profiles. This contribution is limited to a mapping on IEEE 802.3, which is the most frequently used technology in industrial automation.