H.1.1.3 Network Connection

The “network connection” describes one TCP port on one network device. This can be used for a TCP connection over which a DICOM association can be negotiated with one or more Network AEs. It specifies the hostname and TCP port number. A network connection may support multiple Network AEs. The Network AE selection takes place during association negotiation based on the called and calling AE-titles.

Table H.1-6 Attributes of Network Connection Object

Information Field Multiplicity Description
Common Name 0..1 An arbitrary name for the Network Connections object. Can be a meaningful name or any unique sequence of characters. Can be used as the RDN. Note: The “cn” attribute type is a basic LDAP defined type and is a synonym for Common Name.
Hostname 1 This is the DNS name for this particular connection. This is used to obtain the current IP address for connections. Hostname must be sufficiently qualified to be unambiguous for any client DNS user.
Port 0..1 The TCP port that the AE is listening on. (This may be missing for a network connection that only initiates associations.)
TLS CipherSuite 0..N The TLS CipherSuites that are supported on this particular connection. TLS CipherSuites shall be described using an RFC-2246 string representation (e.g. “TLS_RSA_WITH_RC4_128_SHA”)
Installed 0..1 A Boolean value. True if the Network Connection is installed on the network. If not present, information about the installed status of the Network Connection is inherited from the device.

Inclusion of a TLS CipherSuite in a Network Connection capable of accepting associations implies that the TLS protocol must be used to successfully establish an association on the Network Connection.

A single Network AE may be available on multiple network connections. This is often done at servers for availability or performance reasons. For example, at a hospital where each floor is networked to a single hub per floor, the major servers may have direct connections to each of the hubs. This provides better performance and reliability. If the server does not change behavior based on the particular physical network connection, then it can be described as having Network AEs that are available on all of these multiple network connections. A Network AE may also be visible on multiple TCP ports on the same network hardware port, with each TCP port represented as a separate network connection. This would allow, e.g. a TLS-secured DICOM port and a classical un-secured DICOM port to be supported by the same AE.