Hierarchical Routing Topology Terminology

Enterprise Replication uses the terms in the Replication Topology Terms to describe Hierarchical Routing topology.

Table 1. Replication Topology Terms

Term	Definition
Root server	An Enterprise Replication server that is the uppermost level in a hierarchically organized set of information The root is the point from which database servers branch into a logical sequence. All root database servers within Enterprise Replication must be fully interconnected.
Nonroot server	An Enterprise Replication server that is not a root database server but has a complete global catalog and is connected to its parent and to its children
Tree	A data structure that contains database servers that are linked in a hierarchical manner The topmost node is called the root. The root can have zero or more child database servers; the root is the parent database server to its children.
Parent-child	A relationship between database servers in a tree data structure in which the parent is one step closer to the root than the child.
Leaf server	A database server that has a limited catalog and no children.

A nonroot server is similar to a root server except that it forwards all replicated messages for other root servers (and their children) through its parent. All nonroot servers are known to all root and other nonroot servers. A nonroot server might or might not have children. All root and nonroot servers are aware of all other servers in the replication environment.