User manual

Publication 1783-UM003D-EN-E - December 2009 71
Chapter 3
Advanced VLAN Configuration
The advanced VLAN options are the Rapid Spanning Tree Protocol (RSTP)
and the Internet Group Management Protocol (IGMP) snooping features on
the switch ports. These options are enabled by default.
We recommend that you leave these options enabled for the benefits that they
provide.
• RSTP prevents network loops by enabling only one active path for
traffic to use.
RSTP also provides a redundant path if the active path becomes
unavailable.
• IGMP snooping reduces duplicate and excess traffic on the network by
forwarding IP multicast traffic to specific switch ports rather than by
flooding all ports.
With IGMP snooping, only ports that are members of specific IP
multicast groups receive multicast messages. The result is a more
efficient use of bandwidth.
IMPORTANT
Disabling RSTP can affect connectivity to the network. Because
many EtherNet/IP applications use multicast extensively,
disabling IGMP snooping can adversely affect the network
performance.