Difference between the options --call and --aetitle of echoscu

[Jyoti]

Hi,

I want to know what exactly is the difference between the options --call and --aetitle of the command echoscu? The man pages say :

-aet --aetitle aetitle: string
set my calling AE title (default: ECHOSCU)
-aec --call aetitle: string
set called AE title of peer (default: ANY-SCP)

But I am not very clear on what is meant by setting my called AE Title and setting called AE Title.

I am new to DCMTK any any kind of explanation on this would be helpful.

Thanks,
Jyoti

[Marco Eichelberg]

When opening a network connection, the application that initiates the connection transmits two symbolic names to the remote system:

• The Calling Application Entitity Title identifies the client application itself. DICOM does not attach a specific meaning to this symbolic name (except that it uniquely identifies one system in the context of one network), but many systems will use this for a kind of access control: Only known "clients" are allowed to open DICOM associations at all.
• The Called Application Entity Title identifies the server to which the connection is initiated. Most servers will refuse connections if they are not called with "their" own symbolic name. Again, this is implementation specific behaviour and other servers (such as storescp) will simply ignore both aetitles.

A bit of background information: When the DICOM network protocol was designed around 1992, there were still multiple "candidates" for LAN protocol over which DICOM could be used, including TCP/IP and OSI. Therefore, DICOM tried to avoid communicating protocol specific network addresses such as TCP/IP adresses or port numbers over the application level protocol and instead introduced the notion of an "application entity title" which is a symbolic identifier of one application entity (e.g. DICOM service port). For many DICOM protocols, systems need to be able to map these symbolic aetitles to a network protocol address.