Rockwell Automation Ethernet Design Considerations Reference Manual - Manual (Page 44)

44 Rockwell Automation Publication ENET-RM002C-EN-P - May 2013
Chapter 3 Ethernet Infrastructure Features
VLAN Trunking
Trunking enables a VLAN to span multiple switches.
VLANs and Segmentation Guidelines
Configure separate VLANs for different work cells or areas of your plant.
Configure one VLAN for all data traffic relevant to one particular area or cell
zone. Because 80…90% of traffic is local to one cell, this is the optimal design. All
devices with multicast connections must be on the same VLAN. Within a
VLAN, multicast and unicast traffic can be mixed depending on application
requirements. The default communication type of unicast must be used for
point-to-point communication to minimize device, network, and infrastructure
loading:
• Design small cell or area zones, each with a dedicated VLAN and IP
subnet.
• Restrict data flow out of the cell or area zone unless plantwide operations
explicitly require it.
• Segment traffic types into VLANs and IP subnets to better manage the
traffic and simplify security management.
• Within the cell or area zone, use Layer 2 VLAN trunking between
switches with similar traffic types. When trunking, use 802.1Q, VTP in
transparent mode.
• Use Layer 3 distribution switches to route information between cell or area
Zone VLANs and plantwide operations in the Industrial Zone.
• Enable IP directed broadcast on cell or area zone VLANs with
EtherNet/IP traffic for easy configuration and maintenance from control
systems, such as RSLinx® software.
• Avoid large Layer 2 networks to simplify network management.
• Select switches based on the VLAN features you need:
– Stratix 6000 switches support VLANs.
– Stratix 8000 and Stratix 8300 switches support VLANs and VLAN
trunking, as well as Layer 3 switching (enables routing across VLANs
and subnets).
802.1 Q Trunk
VLAN 102
VLAN 42
VLAN 20
VLAN 102
VLAN 42
VLAN 20