Robert Horn, Agfa Corporation DICOM Configuration Robert Horn, Agfa Corporation

Supplement 67 Existing Industry Protocols Existing Configuration Tools NTP (Network Time Protocol) DHCP (Dynamic Host Configuration Protocol) DNS (Domain Name System) LDAP (Lightweight Directory Access Protocol) Existing Configuration Tools Existing support databases DICOM specific information model for LDAP databases

DICOM Configuration Goals Support New Functions Security and Privacy Synchronized Multi-device Acquisitions Reduce Operational Costs Network Administration AE-Title management Service location management Feature location management

Time Synchronization For Multi-device simultaneous acquisitions Cardiac Catheterization laboratory Coordination Security Logs, Procedure Logs Convenience

Synchronization Specification Specify error relative to time reference(s) Acceptable absolute time error (relative to UTC) o( 1s ) security logs o( 100s ) cardiac catheterization Acceptable synchronization error within a Time Source (0018,1801) (relative to local source) o( 1s ) security logs o( 10ms) cardiac catheterization (a few percent of one cycle of a rapidly beating heart).

NTP - Network Time Protocol Widely available Suitable for both low precision time and high precision time synchronization SNTP (Simple NTP) clients for low precision and limited capability systems. Extensively documented and explained on www.ntp.org

Accuracy capability of NTP o(1s) Either client (NTP,SNTP), network capable OS, Internet, GPS, or radio connection o(250ms) NTP client, interrupt driven OS, NTP clock controls o(100ms) local network topology o(10ms) OS clock, OS design o(1 ms) OS/application design, network topology o(100 us) Hardware assist, OS/application design o(10 us) Instrumentation clock, custom OS o(1 us) Atomic clock, extensive hardware assist

How NTP works Mathematical Magic happens Query Time Sent (Ta) Response Time Query Received (Ti) Time Response Sent (Tj) Current Time Parameters (TP) Redundant Servers NTP Server Client Provides Old Network Parameters Old Time Parameters Query Response Mathematical Magic happens Client Sets and Fine Tunes System Clock SNTP performs only the clock setting NTP includes the network delay estimation, optimal estimation mathematics and fine tuning of the system clock. NTP Client NTP clients may utilize redundant servers NTP clients may utilize instrumentation grade pulse generators (e.g. Atomic Clocks)

Typical NTP configurations Internet NTP Server GPS Receiver Campus Network NTP Clients Switching Hub Local NTP Server

Network admin DHCP (Dynamic Host Configuration Protocol) Assigns IP address, hostname Informs DNS of assignment Provides routing, NTP, DNS, etc. information to client DNS (Domain Name System) Provides hostname to IP lookup services Provides server location lookup services LDAP (Lightweight Directory Access Protocol) Provides simple information directory services

DHCP Widely used Support stable IP allocation (needed for transition and legacy equipment) Supports dynamic IP allocation Understood by IT administrators Documents network IP configuration in file Devices only need their "name"

DNS Widely used Provides translation from hostname to IP DHCP uses DDNS option to maintain coordination with dynamic IP assignments RR SRV records provide location of LDAP server

LDAP Widely used (known as Active Directory in Windows) Simple query oriented network database Simple information model. Schema provided as part of Supplement 67. Alternatives examined CIM: very attractive, but a much larger effort to define and implement. Not yet widely used. SNMP, DMTF: interesting but deal with different aspects of network administration and management.

Locate AE-title (internal operation) LDAP Server Where is AE-X AE-X is at hostname, port Database Where is hostname? DNS Server Hostname is x.y.z.w DICOM Traffic

Beyond Finding AE-Titles Installation and Network Configuration oriented AE Configuration Obtain new unique AE-Title SOP Classes supported (SCU/SCP, Transfer Syntaxes) IHE Actor Vendor extension Device Configuration Description Hospital extension

Pre-configured Installation Large network addition Multiple vendors Reduce coordination and scheduling delays Reduce configuration errors Reduce staging requirements

Pre-configured Installation Vendor A Preparation LDAP Prepared Configurations LDIF IT Organization DHCP Network Planning A A LDIF A Prepared Configurations A B B B Vendor B preparation

Add another machine DHCP Install Hardware Assign Name DNS LDAP Get IP, hostname, etc. DHCP Install Hardware Assign Name Find LDAP Server DNS LDAP Query Configuration Configure System Obtain Unique AE Titles Update Configuration

Hospital network reconfiguration DHCP Server Shutdown (DHCP) Revise DHCP Configuration Resume DHCP Modify network hardware Clients Resume

Customer Assisted Maintenance Simple device swap Remote reconfiguration Local reconfiguration