Ross Opengear FED-6943, User Manual, Page: 76 / 92

9–10 • Configuration Fiber Ethernet Switch Transceivers User Manual (Iss. 04)
Troubleshooting a Loop
When a loop is created, the Fiber Ethernet Switch Transceiver may automatically detect the loop
and disable the appropriate ports. When this occurs, the LEDs on the rear module and the
card-edge flash in unison for the affected ports. Note that the network may be able to avoid the
loop if it has spanning tree capability.
Use one of the following methods to troubleshoot:
• Disable the ports in DashBoard and enable them one at a time to see which port is causing
the loop.
• Disconnect the cables from the ports on the rear modules and then re-connect the cables
one at a time.
• Disconnect the cables from the ports, re-configure the card, and then re-connect the
cables one at a time. Use this method when DashBoard cannot connect to the card.
Exceptions
There are exceptions for permitting a looping system: multiple paths are created for redundancy
or for high bandwidth traffic. In the case of the Fiber Ethernet Switch Transceivers, you can have
two or more ports acting as a trunk group to increase the bandwidth between two points. The
trunk appears as one port in the generic switch mode of operation. It also provides redundancy in
that failure of one of the physical ports in the trunk group forces all the traffic to the remaining
link(s).
Figure 9.8 illustrates a setup with multiple FET-6945 cards that are set for trunking at
double the bandwidth of a single link between the two cards.
Configuring a Trunking Group
The ports on each Fiber Ethernet Switch Transceiver card can be set up for 1:1 trunking between
any ports or for redundant/load sharing trunking (such as two fiber links to three or four copper
links with auto failover). Each card supports two trunk groups between two devices with each
trunk group having up to four ports.
In a configuration such as in Figure 9.11 , you have multiple bandwidths and redundancy between
the multiple Corporate Networks with fiber connections. Note that each Corporate Network must
be configured to recognize these links are part of a trunk.
Figure 9.11 Setup of Multiple Bandwidths with Redundancy
Important
— When using an FED-6942 series, FED-6943 series, FET-6945 series,
or FET-6946 series card, there is a potential of a 30 second delay in the event of a link
failure on Fiber B or Fiber C before traffic switches to an alternate port in the trunk
group. Refer to the section “
To configure a Trunk Group ” on page 9-11 for details on
assigning ports to a trunk group.
Corporate
Network 1
Corporate
Network 2
FES-6941-40B
FES-6941-40A