Concept Guide

NOTE: TDR is an intrusive test. Do not run TDR on a link that is up and passing trac.
To test and display TDR results, use the following commands.
1 To test for cable faults on the TenGigabitEthernet cable.
EXEC Privilege mode
tdr-cable-test tengigabitethernet slot/port
Between two ports, do not start the test on both ends of the cable.
Enable the interface before starting the test.
Enable the port to run the test or the test prints an error message.
2 Displays TDR test results.
EXEC Privilege mode
show tdr tengigabitethernet slot/port
Conguring wavelength for 10–Gigabit SFP+ optics
You can set the wavelength for tunable 10–Gigabit SFP+ optics using the wavelength command. To set the wavelength, follow these
steps:
• Enter the interface mode and set the wavelength.
INTERFACE mode
wavelength 1529.0
The wavelength range is from 1528.3 nm to 1568.77nm.
• Verify conguration changes.
INTERFACE mode
show config
Link Dampening
Interface state changes occur when interfaces are administratively brought up or down or if an interface state changes.
Every time an interface changes a state or aps, routing protocols are notied of the status of the routes that are aected by the change in
state. These protocols go through the momentous task of re-converging. Flapping; therefore, puts the status of entire network at risk of
transient loops and black holes. Dampening limits the notication of status to the routing protocols. Link dampening minimizes the risk
created by apping by imposing a penalty (1024) for each interface ap and decaying the penalty exponentially based on the half-time.
When the accumulated penalty exceeds a certain threshold (suppress threshold), the interface is put in an Error-Disabled state and for all
practical purposes of routing, the interface is deemed to be “down.” After the interface becomes stable and the penalty decays below a
certain threshold (reuse threshold), the interface comes up again and the routing protocols re-converge.
You congure link dampening using the dampening [[[[half-life] [reuse-threshold]] [suppress-threshold]]
[max-suppress-time]] command on the interface.
Following is the detailed explanation of interface state change events:
• suppress-threshold— The suppress threshold is a value that triggers a apping interface to dampen. The system adds penalty
when the interface state goes up and down. When the accumulated penalty reaches the default or congured suppress threshold, the
interface state changes to Error-Disabled state. The range of suppress threshold is from 1 to 20000. The default is 2500.
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Interfaces