Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.14.1.0 - Page 421

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 Configuring 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 configuration 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 flaps, routing protocols are notified of the status of the routes that are affected 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 notification of status to the routing protocols. Link dampening minimizes the risk created by flapping by imposing a penalty (1024) for each interface flap 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 configure 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 flapping interface to dampen. The system adds penalty when the interface state goes up and down. When the accumulated penalty reaches the default or configured suppress threshold, the interface state changes to Error-Disabled state. The range of suppress threshold is from 1 to 20000. The default is 2500. • half-life- The accumulated penalty decays exponentially based on the half-life period. The accumulated penalty decreases half after each half-life period. The range of half-life is from 1 to 30 seconds. The default is 5 seconds. Interfaces 421