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Foundry Configuration Guide for the FESX, FSX, and FWSX
9 - 2
© Foundry Networks, Inc.
December 2005
Figure 9.1
UDLD example
Normally, a Foundry device load balances traffic across the ports in a trunk group. In this example, each Foundry
device load balances traffic across two ports. Without the UDLD feature, a link failure on a link that is not directly
attached to one of the Foundry devices is undetected by the Foundry devices. As a result, the Foundry devices
continue to send traffic on the ports connected to the failed link.
When UDLD is enabled on the trunk ports on each Foundry device, the devices detect the failed link, disable the
ports connected to the failed link, and use the remaining ports in the trunk group to forward the traffic.
Ports enabled for UDLD exchange proprietary health-check packets once every second (the keepalive interval). If
a port does not receive a health-check packet from the port at the other end of the link within the keepalive
interval, the port waits for two more intervals. If the port still does not receive a health-check packet after waiting
for three intervals, the port concludes that the link has failed and takes the port down.
Configuration Considerations
•
This feature is supported only on Ethernet ports.
•
To configure UDLD on a trunk group, you must enable and configure the feature on each port of the group
individually. Configuring UDLD on a trunk group’s primary port enables the feature on that port only.
•
Dynamic trunking is not supported. If you want to configure a trunk group that contains ports on which UDLD
is enabled, you must remove the UDLD configuration from the ports. After you create the trunk group, you
can re-add the UDLD configuration.
Enabling UDLD
To enable UDLD on a port, enter a command such as the following at the global CONFIG level of the CLI:
FastIron SuperX Router(config)# link-keepalive ethernet 1/1
To enable the feature on a trunk group, enter commands such as the following:
FastIron SuperX Router(config)# link-keepalive ethernet 1/1 ethernet 1/2
FastIron SuperX Router(config)# link-keepalive ethernet 1/3 ethernet 1/4
These commands enable UDLD on ports 1/1 – 1/4. You can specify up to two ports on the same command line.
Syntax:
[no] link-keepalive ethernet [<slotnum>/]<portnum> [ethernet [<slotnum>/]<portnum>]
The <slotnum> parameter is required on chassis devices.
X
Without link keepalive, the Foundry ports remain
enabled. Traffic continues to be load balanced to the
ports connected to the failed link.
When link keepalive is enabled, the feature
brings down the Foundry ports connected
to the failed link.
Foundry Device
Foundry Device
Summary of Contents for FastIron Edge Switch X424
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