Rockwell Automation 1783-BMxxx Stratix 5700 Ethernet Managed Switches User Manual - Manual (Page 100)

100 Rockwell Automation Publication 1783-UM004E-EN-P - June 2014
Chapter 3 Switch Software Features
DHCP Persistence Every device in an IP-based network must have a unique IP address. The
Dynamic Host Configuration Protocol (DHCP) automatically assigns IP
address information from a pool of available addresses to newly connected
devices (DHCP clients) in the network. If a device leaves and then re-joins the
network, the device receives the next available IP address, which can or cannot be
the same address that it had before.
The switch can be set to operate as a DHCP server to provide DHCP
persistence. With DHCP persistence, you can assign a specific IP address to each
port to make sure that a device attached to a specific port receives the same IP
address. This feature works with only a single device connected to each port
configured for DHCP persistence.
CIP Sync Time
Synchronization
(Precision Time Protocol) The IEEE 1588 standard defines a protocol called Precision Time Protocol
(PTP) that enables precise synchronization of clocks in measurement and control
systems. We refer to this as CIP Sync time synchronization. The clocks are
synchronized over the EtherNet/IP communication network. PTP enables
systems that include clocks of various precision, resolution, and stability to
synchronize. PTP generates a Master-Slave relationship among the clocks in the
system. All clocks ultimately derive their time from a clock selected as the
Grandmaster clock.
Three PTP modes are available for the switches:
• Boundary Clock
• Transparent Clock
• Forwarding (PTP is disabled when Forwarding mode is selected)
For more information on these modes, refer to the Converged Plantwide
Ethernet Design and Implementation Guide, publication
ENET-TD001 .
The default PTP mode is Forwarding mode.
IMPORTANT To make sure DHCP persistence works correctly, follow the application rules.