How are Synchronization Loops avoided?
In a synchonization loop the time derived from one source along a specific path of servers is used as reference time again within such a path. This may cause an excessive accumulation of errors is is to be avoided. Therefore NTP uses different means to accomplish that: • The Internet address of a time source is used as reference identifier to avoid duplicates. The reference identifier is limited to 32 bits however. • The stratum as described in Q: 5.1.4.1. is used to form an acyclic synchronization network. More precisely[2], the algorithm finds a shortest path spanning tree with metric based on synchronization distance dominated by hop count. The reference identifier provides additional information to avoid neighbor loops under conditions where the topology is changing rapidly. This is a very well known problem with algorithms such as this. See any textbook on computer network routing algorithms. Computer Networks by Bertsekas and Gallagher is a good one. In IPv6 the reference ID fiel
