in NetScaler, Traffic Management

Advanced Health Check to DICOM Service

Digital Imaging and Communications in Medicine (DICOM) is standard that holds a protocol and is used, amongst other things, for retrieving images from medical imaging equipment. Is uses TCP/IP but if you want to do a health check you need to do a special ping in stead of a regular ping, the DICOM ping (or it’s original name C-ECHO). This DICOM ping checks more than just network connectivity, so a great base for an in depth health check when load balancing DICOM services with NetScaler.

UPDATE: GE asked me to remove links to copyrighted materials. For that reason the named files are no longer available and this article is here for reference only.

For this you need some special files to initiate the ping. You can compile this yourself on BSD if you have the time and knowledge, but Erez Baruch was so friendly to share the compiled versions. Gerben Lammertink (please thank both of them if you find this useful) was so kind enough to figure out how to script this on NetScaler and wrote down the procedure to create a usable health monitor on NetScaler. And here it is.

Requirements

Besides a NetScaler an the info and downloads on this page there is not much you need. What was uses to test:

  • NetScaler 10.1.x
  • SSH Client
  • SCP client

This is tested on NetScaler 10.1.x , please comment if you can test this on NS 10.5 as the BSD version on 10.5 is different

 

Procedure

Below are the steps you need to take to get this working. It is rather straightforward.

  1. Get the required DICOM files on the NetScaler
    For this you need to SSH into the NS and use SCP to transfer the files on to the BSD shell. The files you need are:

    1. Place dicom.dic in: /nsconfig/monitors/dicom/lib/
    2. Place echoscu in: /nsconfig/monitors/dicom/bin/
  2. Create the DICOM ping script
    The DICOM ping script will hit echoscu to perfom the ping with the correct arguments. Place executable dicomPinger in: /nsconfig/monitors/dicom/bin/The content of dicomPinger is protected by Copyright and GE kindly asked me not to post the script. Please use other resources to obtain the script.
  3. Create the monitor PERL script
    This will be the script that we will configure as a user monitor in the NetScaler GUI and users all the files and scripts created before. The script “dicom.pl” must be placed in: /nsconfig/monitors/The Script needs some arguments to know where to connect to, the port number and the AE Title. This leads to

    dicom.pl (make sure it’s executable : chmod +x dicom.pl)
  4. Create a monitor of type “USER”
    Last step is to add the monitor in the GUI and select the create dicom.pl script to use, including the correct parameters as described in the previous bullet.
    dicom - special parameters

Resources

  •  I must give credit where credit is due and although this states my , it is the fruit of Erez Baruch and Gerben Lammertink their labor. Thank you!

 

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