**Time Synchronization in IP Networks**

**Moshe Sidi (a joint work with
O. Gurewitz and I. Cidon)**
**Abstract:**

Time synchronization is critical in distributed environments. A
variety of network protocols, middleware and business applications
rely on proper time synchronization across the computational
infrastructure and depend on the clock accuracy.
The "Network Time Protocol"
(NTP) is the current widely accepted standard for synchronizing
clocks over the internet. NTP uses a hierarchical scheme in order
to synchronize the clocks in the network. In this talk we present
a novel non-hierarchical peer-to-peer approach for time
synchronization termed CTP - Classless Time Protocol.
This approach exploits convex optimization theory
in order to evaluate the impact of each clock offset on the
overall objective function. We define the clock offset problem as an
optimization problem and derive its optimal solution.
Based on the solution we introduce a distributed protocol
that can be implemented over a communication network, prove its
convergence to the optimal clock offsets and show its properties.
We also present methodology and numerical results for
evaluating and comparing the accuracy of time synchronization
schemes. We show that the CTP substantially outperforms
hierarchical schemes such as NTP in the sense of clock accuracy
with respect to a universal clock, without increasing complexity.