- Virtual Network Discovery and Browsing
- Virtual Nework Description
- Virtual Network Description Maintenance
A 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
- Virtual Networks becoming a reality at the DMC – Volume 6, Number 3
- Virtual Networks at the IRIS DMC – Volume 8 Number 4
Virtual Network Discovery and Browsing:
- MetaData Aggregator Includes a list of public virtual networks (below the traditional networks) in expanded form and combined with station metadata.
- Vnets interface Shows the current virtual network descriptions (VNDs) loaded in the DMC’s database. This interface also allows downloading of VNDs in either MS-Excel (.xls) format or command-separated value format.
- SeismiQuery Virtual Network Query Form Allows for flexible searching of virtual networks when needed.
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.
|Virtual network||Virtual network code|
|Network||FDSN/SEED network code|
|Station||FDSN/SEED station code, may be
|Install date||Station installation date, optional|
|Certification date||Station certification date, optional|
|Start date & time||Start of station in this VND, two fields for date and time|
|End date & time||End of station in this VND, two fields for date and time|
|Primary DC||Primary data center affiliation code|
|Secondary DC||Secondary data center affiliation code|
Each unique primary and secondary data center affiliation code must be included in a VND and indicate a URL to the given data center. As an example the VND for the GSN is easy obtained in comma-separated value (.csv) format using the vnets interface: _GSN VND in comma-separated value format
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
- A VND completely defines a virtual network, there are no partial updates.
- The required fields are: virtual network, network, station, start date, start time, end date and end time, all other fields are optional.
- The station field may be
*to indicate all stations from the network.
- The date fields are in
YYYY/MM/DDformat and the time fields are in
- Any primary or secondary codes must be accompanied by matching
DCC:lines indicating a URL for the data center.
- Only lines starting with a virtual network code or
DCC:are parsed from the VND, all other lines are ignored. The Vnets interface includes more lines for informational purposes only.
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.