Rockwell Automation Ethernet Design Considerations Reference Manual - Manual (Page 58)

58 Rockwell Automation Publication ENET-RM002C-EN-P - May 2013
Chapter 3 Ethernet Infrastructure Features
Device Commissioning There are multiple methods for assigning IP addresses. Switches on the product,
such as thumbwheels, push buttons, or HIM modules, provide a static address
that survives power cycles.
Stratix switches support DHCP port allocation. DHCP port allocation is a
hybrid solution for IP addressing because it provides easy device replacement, but
is topology dependant.
Option Description
Static Devices are hard-coded with an IP address.
Advantage
Simple to commission and replace
Disadvantage
In large environments, can be burdensome to maintain
Static via BOOTP
configuration A server assigns devices an IP address.
Precursor to DHCP
Advantage
Supported by every device
Disadvantages
• Requires technician to configure IP address/MAC address when a device is replaced
• Requires a PC for commissioning and replacement (unless there are switches to set the
address offline)
• Adds complexity and point of failure
DHCP A server assigns IP addresses from a pool (not recommended).
Advantages
• Efficient use of IP address range
• Can reduce administration work load
Disadvantages
• More complex to implement and adds a point of failure
• Devices get different IP addresses when they reboot
DHCP option 82 A server assigns consistent IP addresses from a pool (not recommended).
Advantages
• Efficient use of IP address range
• Can reduce administration work load
Disadvantages
• More complex to implement and adds a point of failure
• Mixed environments do not always work
DHCP port-based
allocation IP addresses are automatically assigned per physical switch port.
Advantages
• Efficient use of IP address range
• Eases maintenance and replacement in large environments
Disadvantage
Requires some maintenance and upkeep on a per switch basis