Speaking of IP configuration. To establish a successful DICOM association you'll need the AET, IP and Port to remain consistent. An IP that is dynamic or in other words, an IP that changes (after reboots or reconnection to the network) will result in a failed DICOM association. Remember, a DICOM association is between two DICOM devices. In most cases the AET, IP and Port are configured on both devices. Changes to these values on either party may result in a failed connection.

Therefore, the IP of an AE should be same value consistently.

In this scenario, the server resides in a data center where the physical box is connected to the network through a wired ethernet jack. We must ensure the IP remains static. Perform a ipconfig /all to check if Dynamic Host Control Protocol (DHCP) is enabled on the wired Network Interface Card (NIC). Use the information to answer the quiz below.

You may have answered that the DICOM association will fail. To be fair, it was a trick question.

After what was explained about having static IPs, it would make sense that if an IP is dynamic (using Dynamic Host Control Protocol), then the DICOM association would fail due to inconsistent IP addresses of our server. However, there is another way of keeping the IP the same. We keep the server on DHCP, but configure the network for DHCP Reservation.

In other words, have the networking team reserve an IP for this device on the network Switch.

IP Address in DICOM entities

There are two ways of configuring a IP address to remain the same.

1. Disable DHCP. Hard code the local NIC to be static.
2. Leave the device on DHCP. Reserve a specific IP for it on the network.

1. Static IP Address

• Manual Configuration: The IP address is configured manually on the device itself (e.g., printer, server).
• No DHCP Involvement: The DHCP server is not involved; the device always uses the manually assigned IP.
• Use Case: Typically used for critical infrastructure devices (servers, DICOM modalities) where absolute certainty of IP address configuration is needed, and where reliance on a DHCP server is undesirable.
• Example: A wired DICOM modality such as a CT is manually configured with a static IP address of 192.168.1.10.

Pros:

• No reliance on a DHCP server for IP assignment.
• Complete control over IP address management.

Cons:

• More time-consuming, especially for large networks.
• Changes (like gateway or DNS settings) must be manually updated on each device.
• Prone to IP conflicts if not carefully managed, especially in large networks.
• Manual updates by the modality vendor or field engineers could result in failed DICOM associations
  
  

2. DHCP Reservation

• Automatic Configuration: The IP address is assigned automatically by the DHCP server such as the network Switch, but the same IP is reserved for the device based on its MAC address. The MAC is unique to each NIC allowing the network switch to recognize and assign an appropriate IP.
• DHCP Server-Dependent: The device still requests an IP from the DHCP server, but the server always grants it the same reserved IP.
• Use Case: Useful for devices that need a consistent IP address (e.g., printers, wireless DICOM modalities) but are easier to manage via a central server.
• Example: A portable X-ray modality is configured to always get 192.168.1.20 via a DHCP reservation on the Network Switch so it always receives this IP regardless of it's physical location within the hospital.

Pros:

• Easier to manage and update settings (like DNS or gateway) from the DHCP server.
• Reduces manual configuration on devices, simplifying network management.
• Centralized control of IP assignments.

Cons:

• If the DHCP server goes down, devices might lose access to their reserved IPs.
• Relies on the DHCP server for configuration, so misconfigurations on the server can affect multiple devices.

How to Reserve DHCP

As a PACS administrator, you will need to provide the MAC address of the NIC to your networking team and request that they reserve a specific IP address for it.

The MAC address is a unique identifier for each network interface on a device. It typically appears as a series of hexadecimal numbers separated by hyphens. The MAC appears next to the line "Physical Address" in the text above. See if you can find it in the command prompt emulator above.

Note: In most computers or servers there may be multiple network interface cards. In this sample there are two. Be sure to select the correct one.

Ethernet adapter Local Area Connection:

• Physical Address: 00-1A-2B-3C-4D-5E

Wireless LAN adapter Wireless Network Connection:

• Physical Address: 00-1A-2B-3C-4D-6F

Since this is a wired server, you would provide the Ethernet adapter Local Area Connection MAC to your networking team for DHCP reservation.

Servers aren't the only devices that allows you to reserve an IP. You may also reserve IPs for any device or computer as long as it has a network interface card.

For example, if this were a wireless device or a a computer attached to a portable modality like a C-Arm or an Ultrasound, you would need to configure the wireless NIC. You may also reserve an IP for wired networked devices as well.

In most institutions, the network IT policy would be to provide the MAC address and request an IP address reservation. However, some other institutions allow PACS administrators to configure static IP addresses on the modality itself.

How to Configure a Static IP locally

Image: PC Mag/Microsoft

To configure a static IP address on Windows, you begin by accessing your network settings through the system tray and navigating to the network adapter properties. From there, you open the Internet Protocol Version 4 (TCP/IPv4) properties, where you can manually enter the IP address, subnet mask, default gateway, and DNS server addresses.

Once you've input the static IP and related details, save the changes, and the network adapter will use the specified static IP rather than obtaining one automatically from the DHCP server. To verify the configuration, you can run the ipconfig command in the Command Prompt to confirm the IP address and network settings are correct.

You'll need this in your back pocket for configuring a static IP. But for our scenario, the server already has a DHCP address reservation. Let's move on.