3Com 4007, Implementation Manual, Page: 236 / 684

236 C
HAPTER
13: R
ESILIENT
L
INKS
Resilient Links
Overview
Resilient links protect your network against an individual link or device
failure by providing a secondary backup link that is inactive until it is
needed. A resilient link comprises a resilient link pair that contains a main
link and a standby link. If the main link fails, the standby link immediately
takes over the task of the main link. Figure 12 shows a resilient link pair.
Figure 12 Resilient Link Pair
Under normal network conditions, the main link carries your network
traffic. If a signal loss is detected, the device immediately enables the
standby link so that it carries the data and sends a trap to the network
management station to alert you of the signal loss. The standby port
assumes the profile and carries the network traffic of the main port.
If the main link has a higher bandwidth than its standby link, traffic is
switched back to the main link, provided that no loss of link is detected
for 2 minutes. Otherwise, you must manually switch traffic back to the
main link.
Switchover time to the backup link takes less than 1 second, ensuring no
session timeouts and therefore seamless operation.
To keep you informed about network activity, configure the module to
generate an SNMP trap whenever a switchover from one link to the other
occurs or whenever the link state (up or down) of either link in the
resilient pair changes. For more information about how to configure and
enable SNMP traps, see Chapter 23.
Standby
links
Main link
L2 L2
L2 L2
Main link