Virtual Networks at the IRIS DMC
OverviewA virtual network is a group of stations representing an affiliation that goes beyond the traditional bounds of networks to represent an umbrella organization or initiative. A virtual network definition allows the arbitrary grouping of stations each with independent time ranges. Virtual networks are identified by a virtual network code. To differentiate virtual network codes from traditional FDSN/SEED network codes virtual network codes are prefixed with an underscore '_' character. Most of the IRIS DMC's public access tools allow users to query for and access data based on virtual network codes.
A good example of virtual network utility is the Global Seismographic Network (GSN) which is a collection of more than 220 stations from over 10 different networks. Data and information about these stations as a group is accessible using the _GSN virtual network code.
For further discussion of virtual networks at the IRIS DMC refer to the following DMS Electronic Newsletter articles:
Virtual Networks - Volume 6, Number 2 (June 2004)
Virtual Network Discovery and Browsing:
MetaData Aggregator (MDA) » Includes a list of public virtual networks (below the traditional networks) in expanded form and combined with station metadata.
Virtual Network Description (VND)
A virtual network is defined using a Virtual Network Description (VND) which contains a list of network-station pairs each with independent start and end times. The Vnets interface presents VNDs including all fields except the virtual network code. Description of fields
Virtual network :: Virtual network codeEach unique primary and secondary data center affiliation code must be included in a VND and indicate a URL to the given data center.
Virtual Network Description Maintenance
The recommended way to update (or create) a VND is to download a current VND from the Vnets interface, edit as needed and return, usually by email, to the DMC. Note: the DMC will only load pre-approved VNDs.
Important points regarding maintenance:
VNDs can be submitted to the DMC in either MS-Excel (.xls) format or comma-separated value (.csv) format. XML-based MS-Excel formats, i.e. with a .xlsx extension, are not supported.