1. NTP and PTP Random Thoughts on Trade-offs and Scalability IETF 68 TICTOC BOF Karen O’Donoghue +1-540-653-1567

2. 15 March 2007 2 Objective As requested by the BOF organizers:  Kickoff a discussion on the tradeoffs between NTP and PTP (IEEE 1588), in particular as related to scalability Thought provoking slides? As revised by the speaker:  Identify some basic metrics for scalability  Propose a possible way ahead Rationale for revision:  May be a bit premature to discuss specific NTP/PTP tradeoffs (suffice it to say they exist…)

3. 15 March 2007 3 Characteristics of Scalability What are scalability requirements?  Number of clients/slaves supported  Number of servers/masters available  Number of network or infrastructure devices Clock (tod and/or freq) aware (e.g. transparent clocks) Non-clock (tod and/or freq) aware Mixture  Number and types of networks traversed  Logical and Geographic distance  Available bandwidth If a potential WG is limited to infrastructure networks, how can the requirements be narrowed/clarified?

4. 15 March 2007 4 Impacts to Scalability What impacts scalability?  Client/server approach versus Master/slave approach Server/master complexity Client/slave complexity  Hardware requirement  Network design  Communications model Unicast versus Multicast  Protocol Operations Modes of operation (NTP) Types of devices (PTP)  Algorithm complexity Edge cases  Master/server selection and redundancy

5. 15 March 2007 5 Clock Standardization Activities At a Glance IEEE 1588 (PTP) Pros  Designed for high precision applications  Industrial automation and telecom industries have real time requirements Cons  Lacks the robustness and deployment experience of NTP  Currently represents a niche market relative to generic computing equipment and enterprise deployments IETF (NTP) Pros  Scalable and robust  Subnet technology independent  Represents the generic computing equipment market  Wide scale deployment and years of experience Cons  Does not address high end synchronization requirements in an open standard manner IEEE 802.1AS Pros  Hardware time stamp capability available in every Ethernet NIC (mass market availability) Cons  Immature at this point  Targets consumer market (may not be suitable for enterprise or telecom infrastructures) Note: Each of these solutions has some overlap and addresses some unique aspects of the problem (not an apples to apples comparison).

6. 15 March 2007 6 Given that:  There are various solutions addressing parts (but not all) of the problem space  There is a significant investment in this problem space represented by NTP and PTP  There is an expectation that both NTP and PTP will be encountered in the future Perhaps:  There are aspects of both that can be identified and leveraged for a next generation solution  At the very least, an interface between the two should be considered

7. 15 March 2007 7 Possible TICTOC Way Ahead Clarify requirements  Both time and frequency Define a modular architecture  Analyze/Decompose existing solutions in terms of this architecture Identify existing components that can be leveraged in the new modular architecture  Identify any enhancements required to these existing components Define new components needed to complete the architecture  Don’t reinvent the wheel

8. 15 March 2007 8 Discussion?