3Com 3C17203 - SuperStack 3 Switch 4400, Implementation Manual

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20 C
HAPTER
1: S
WITCH
F
EATURES
O
VERVIEW
endstations in each multicast group to which multicast traffic should be
forwarded.
For more information about multicast filtering, see Chapter 3 “Using
Multicast Filtering” .
Resilient Links The resilient link feature enables you to protect critical links and prevent
network downtime should those links fail. Setting up resilient links
ensures that if a main communication link fails, a standby duplicate link
automatically takes over the task of the main link. Each main and standby
link pair is referred to as a resilient link pair.
Resilient links are a simple method of creating redundancy that provides
you with a fast reaction to link failure. Resilient links are quick to set up,
you have full control over their configuration, and the port at the other
end of the resilient link does not have to support any resilience feature.
For more information about resilient links, see Chapter 4 “Using
Resilience Features” .
Spanning Tree
Protocol and Rapid
Spanning Tree
Protocol
Spanning Tree Protocol (STP) and Rapid Spanning Tree Protocol (RSTP)
are bridge-based systems that make your network more resilient to link
failure and also provide protection from network loops — one of the
major causes of broadcast storms.
STP allows you to implement alternative paths for network traffic in the
event of path failure and uses a loop-detection process to:
■
Discover the efficiency of each path.
■
Enable the most efficient path.
■
Disable the less efficient paths.
■
Enable one of the less efficient paths if the most efficient path fails.
RSTP is an enhanced version of the STP feature and is enabled by default.
RSTP can restore a network connection quicker than the legacy STP
feature. RSTP can detect if it is connected to a legacy device that only
supports IEEE 802.1D STP and will automatically downgrade to STP on
that particular port.
STP conforms to the IEEE Std 802.1D, 1998 Edition and RSTP conforms to
the IEEE Std 802.1w-2001.