Enable a network topology

Once a trace network has been created, the network topology must enabled. A network topology is required to perform analytic functionality on network features such as tracing of network features and the creation of network diagrams. When enabled, dirty areas are generated for features where edits are made. These dirty areas are used during the validation of the network topology to ensure it is kept up to date.

The network topology for a trace network is enabled using the Enable Network Topology geoprocessing tool and establishes connectivity between feature classes based on geometric coincidence (x,y,z). This process also generates error features to mark any network errors discovered. The enable process requires an exclusive lock, so all editing is blocked while the network topology is being enabled. If the network topology has previously been enabled, any existing error features are deleted and repopulated.

Note:

The Enable Network Topology tool does not use Z to determine connectivity unless all features that participate in the trace network are z-enabled.

Enable a network topology to work with dirty areas, tracing, and network diagrams

To work with dirty areas, run traces, and generate a diagram, the network topology must be enabled on a trace network. The network topology is created after a trace network is created and data has been loaded. Error features are also generated at this stage to mark errors in your network.

The network topology can be disabled to perform planned configuration changes or larger data loading operations.

Requirements

The following requirements must be met to enable a network topology:

• All network feature classes must have a spatial index.
• Connectivity in the trace network is based on the geometric coincidence (x,y,z) of features.
• When a network topology is enabled for a trace network, z-values are used to establish connectivity when all feature classes that participate in the network are also z-enabled.

  Note:

  If a conflict exists between the z-values of a junction and coincident edge endpoint vertices, the build process does not establish connectivity between the features, and a system junction that shares the z-value of the connected edge is created.

When working with an enterprise geodatabase, the following requirements apply:

• The Input Trace Network parameter must be from a database connection established as the database trace network owner.

• This tool must be run when connected to the default version.

• The trace network must be registered as branch versioned.

• The trace network must be in a nonversioned state to use the Only generate errors advanced option.

To enable a network topology, complete the following steps:

1. On the Analysis tab, in the Geoprocessing group, click Tools to open the Geoprocessing pane.
2. In the Geoprocessing pane, search for and choose Enable Network Topology.
3. For the Input Trace Network parameter, specify the trace network.
4. Optionally, in the Advanced Options section, restrict the number of errors processed by the operation.

   This error number is a sum of the errors generated for both the point and line error feature tables. Once the maximum number of errors specified is reached, the operation is aborted, the tool fails, and no errors are written. When no value is provided for this parameter, this allows an infinite number of errors to be discovered. The default value is 10,000.

   Caution:

   Increasing this value will result in an increase in the length of time required for the enable operation.
5. Click Run.

The network topology is created for the specified trace network. The errors are written to the Point Error and Line Error feature classes for review. Dirty areas may be present if error features were generated.

Discover errors before enabling network topology

The Enable Network Topology tool can be run with the Only generate errors option to generate errors without creating the network topology. This is done to generate errors and perform quality assurance and prototyping on your network configuration and features before fully enabling the network topology and registering as versioned (for enterprise geodatabases). Use this process to review and correct errors by making edits to trace network features. Analytic capabilities are not enabled at this stage, so dirty area creation, tracing, and network diagrams are not available.

The following requirements must be met to use the Only generate errors option:

• An exclusive schema lock must be obtained.
• All network feature classes must have a spatial index.

The following apply when working with an enterprise geodatabase:

• The Input Trace Network parameter must be from a database connection established as the database trace network owner.

• The trace network must be in a nonversioned state to use the Only generate errors advanced option.

To review network errors without enabling the network topology, complete the following steps:

1. On the Analysis tab, in the Geoprocessing group, click Tools to open the Geoprocessing pane.
2. In the Geoprocessing pane, search for and choose Enable Network Topology.
3. For Input Trace Network, specify the trace network.
4. Optionally, in the Advanced Options section, restrict the number of errors processed by the operation.

   This error number is a sum of the errors generated across the two error feature tables. Once the maximum number of errors specified is reached, the operation is aborted and the tool fails. When no value is provided for this parameter, this allows an infinite number of errors to be discovered. The default value is 10,000.

   Caution:

   Increasing this parameter to a higher value is not recommended and will result in an increase in the length of time for the enable operation.
5. In the Advanced Options section, check the Only generate errors check box.
6. Click Run.

Error features are generated for inconsistences in your network, and the network topology remains in a disabled state.