S.5 Adding The First Managed Device to A Legacy Network

The addition of the first fully managed device to a legacy network requires both server setup and device setup.

S.5.1 New Servers Required

The managed node requires that servers be installed or assigned to provide the following actors:

  1. DHCP Server

  2. DNS Server

  3. NTP Server

  4. LDAP Server

These may be existing servers that need only administrative additions, they may be existing hardware that has new software added, and these may be one or multiple different systems. DHCP, DNS, and NTP services are provided by a very wide variety of equipment.

S.5.2 NTP

The NTP server location relative to this device should be reviewed to be sure that it meets the timing requirements of the device. If it is an NTP client with a time accuracy requirement of approximately 1 second, almost any NTP server location will be acceptable. For SNTP clients and devices with high time accuracy requirements, it is possible that an additional NTP server or network topology adjustment may be needed.

If the NTP server is using secured time information, certificates or passwords may need to be exchanged.

S.5.3 Documenting Managed and Unmanaged Nodes (DHCP, DNS, and LDAP)

S.5.3.1 DHCP Documentation

There are advantages to documenting the unmanaged nodes in the DHCP database. This is not critical for operations, but it helps avoid administrative errors. Most DHCP servers support the definition of pre-allocated static IP addresses. The unmanaged nodes can be documented by including entries for static IP addresses for the unmanaged nodes. These nodes will not be using the DHCP server initially, but having their entries in the DHCP database helps reduce errors and simplifies gradual transitions. The DHCP database can be used to document the manually assigned IP addresses in a way that avoids unintentional duplication.

The managed node must be documented in the DHCP database. The NTP and DNS server locations must be specified.

If this device is an association acceptor it probably should be assigned a fixed IP address. Many legacy devices cannot operate properly when communicating with devices that have dynamically assigned IP addresses. The legacy device does not utilize the DNS system, so the DDNS updates that maintain the changing IP address are not available. So most managed nodes that are association acceptors must be assigned a static IP address. The DHCP system still provides the IP address to the device during the boot process, but it is configured to always provide the same IP address every time. The legacy systems are configured to use that IP address.

S.5.3.2 DNS Documentation

Most DNS servers have a database for hostname to IP relationships that is similar to the DHCP database. The unmanaged devices that will be used by the managed node must have entries in this database so that machine IP addresses can be found. It is often convenient to document all of the hostnames and IP addresses for the network into the DNS database. This is a fairly routine administrative task and can be done for the entire network and maintained manually as devices are added, moved, or removed. There are many administrative tools that expect DNS information about all network devices, and this makes that information available.

If DDNS updates are being used, the manually maintained portion of the DNS database must be adjusted to avoid conflicts.

There must be DNS entries provided for every device that will be used by the managed node.

S.5.3.3 LDAP Documentation

The LDAP database should be configured to include device descriptions for this managed device, and there should be descriptions for the other devices that this device will communicate with. The first portion is used by this device during its start up configuration process. The second portion is used by this device to find the services that it will use.

The basic structural components of the DICOM information must be present on the LDAP server so that this device can find the DICOM root and its own entry. It is a good idea to fully populate the AE Title registry so that as managed devices are added there are no AE Title conflicts.

S.5.3.4 Descriptions of Other Devices

This device needs to be able to find the association acceptors (usually SCPs) that it will use during normal operation. These may need to be manually configured into the LDAP server. Their descriptions can be highly incomplete if these other devices are not managed devices. Only enough information is needed to meet the needs of this device. If this device is manually configured and makes no LDAP queries to find services, then none of the other device descriptions are needed.

There are some advantages to manually maintaining the LDAP database for unmanaged devices. This can document the manually assigned AE Titles. The service and network connection information can be very useful during network planning and troubleshooting. The database can also be useful during service operations on unmanaged devices as a documentation aid. The decision whether to use the LDAP database as a documentation aid often depends upon the features provided with the LDAP server. If it has good tools for manually updating the LDAP database and good tools for querying and reporting, it is often a good investment to create a manually maintained LDAP database.

S.5.4 Description of This Device

This device needs its own LDAP entry. This is used during the system start up process. The LDAP server updates must be performed.