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iRule to route DICOM by study type

Synopsis: We route all DICOM traffic coming in on port 104 to the DICOM pool. However, we are expanding and taking on larger studies, such as mammography, tomography, and large CT. With larger studies, we have DICOM that backs up when being consolidated on the PACS.

What we would like is to be able to route DICOM by study type. That is, we inspect the packet and if it is for CT we route to the CT pool, if for MG we route to the MG pool. Has anyone done this? It is difficult to be able to perform packet analysis on a live system.

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USER ACCEPTED ANSWER & F5 ACCEPTED ANSWER

Sine F5 doesn't have a way to read the metadata or EXIF data in DICOM images, you would need another way to identify the study type. If you can have a file name policy or add a path for transfer to the PACS, the F5 could interpret that as the study and change the pool on the fly pretty easily.

You can also take some tcp dumps from the live F5 without effect to the production system by using tcpdump or tshark.

If you have APM, you could also base pool selection on the authenticated user. So for example, A user would authenticate, APM would determine they are in the Tomography department, and F5 would set CT_pool.

Something like the following, without APM MAY work if you have a standard naming policy:

when HTTP_REQUEST {
  if { [HTTP::path] contains "mammo" }{
    pool mammo_pool
  } elseif { [HTTP::path] contains "tomo" }{
    pool tomo_pool
  } else {
    pool pacs_pool
  }
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USER ACCEPTED ANSWER & F5 ACCEPTED ANSWER

I know this is about 5 years old at this point, but, we are also trying to make smart routing decisions based on DICOM info. There are iRule possibilities, but iRule documentation is extremely segmented with few examples outside of "web" traffic, like the previous answer. Those of us looking for deeper solutions, looking into the TCP packet to make decisions, not much out there. However, to this person I would have said, for modality type based decisions, invest in a DICOM Router like Laurel Bridge Compass. It has the ability to make routing decisions based on DICOM information it gathers from the DICOM headers (HTTP examples, etc are useless in DICOM). Laurel Bridge also has a basic 'balancing' (round robin with heartbeat sensing), so it can get close to th Big IP in that aspect. I wish there more support for non HTTP in the Big IP world, better documentation, etc. Until then, right now it's either become an iRule guru and figure it out on your own or look for another solution.

BoL -PC

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