3Com 1000 Switch User Manual


 
Setting Up Resilient Links 4-19
Setting Up Resilient Links
You can configure a Switch to provide resilient links
to another device so that network disruption is mini-
mized if a link fails. A
resilient link pair
consists of a
main link and a standby link. You define a resilient
link pair by specifying the main port and standby
port at one end of the pair.
Figure 4-13
Resilient link pair
Under normal network operating conditions, the
main link carries your data. The Receive Idle signal
of a fiber link or the Test Pulse on an Ethernet
twisted pair link is continually monitored by the
Switch. If a signal loss is detected, the Switch imme-
diately enables the standby port so that it carries the
data. In addition, the main port is disabled.
If a main link has a higher bandwidth than its
standby link, traffic is automatically switched back to
the main link provided no loss of link is detected for
two minutes. Otherwise, you need to manually
switch traffic back to the main link.
When setting up resilient links, you should note the
following:
Up to 13 resilient link pairs can be configured on
a 24-port Switch 1000, and up to seven pairs can
be configured on a 12-port Switch 1000.
Resilient links cannot be set up if Spanning Tree
(STP) is enabled on the Switch.
Resilient Links can only be set up on fiber or
twisted pair links. The main and standby links in
the same pair, however, can use any combina-
tion of these media.
A resilient link pair can only be set up if:
The ports belong to the same VLAN.
The ports have an identical security setting.
Neither of the ports forms part of another
resilient link pair.
If the main port is VLT (Virtual LAN Trunk) port,
the standby port must also be a VLT port.
A resilient link pair must be defined at only one
end of the connection.
You cannot disable any port that is part of a resil-
ient link pair.