Rockwell Automation Ethernet Design Considerations Reference Manual - Manual (Page 49)

Rockwell Automation Publication ENET-RM002C-EN-P - May 2013 49
Ethernet Infrastructure Features Chapter 3
EtherChannel Protocol
The EtherChannel protocol combines multiple physical switch ports into one
logical connection to increase bandwidth through load balancing, as well as
physical connection redundancy.
This protocol groups several physical Ethernet links to create one logical
Ethernet link for the purpose of providing fault-tolerance and high-speed links
between switches, routers, and servers. An EtherChannel can combine 2…8
active Fast Ethernet or Gigabit Ethernet ports:
• Link Aggregation Control Protocol (LACP) port aggregation—IEEE
802.3ad
• Built into Stratix 8000 and Stratix 8300 switches
• Requires a redundant star topology
• Provides resiliency between connected switches if a connection is broken
Fault-tolerance is a key aspect of EtherChannel. If a link fails, the EtherChannel
technology automatically redistributes traffic across the remaining links. This
automatic recovery takes less than one second and is transparent to network
applications and the end user. This makes it very resilient.
STP can be used with an EtherChannel. STP treats all the links as a single
connection. Without the use of an EtherChannel, STP shuts down any
redundant links between switches until one connection goes down. This is where
an EtherChannel is most desirable because it enables full use of all available links
between two devices.
Distribution Switches
Catalyst 3750 Switch Stack
F F
F
F
Stratix 8000
Access Switches
F = Forwarding