Dell Force10 Z9000 FTOS Configuration Guide for Z9000 System - Page 406

www.dell.com | support.dell.com Disable ports when one only SFM is available (E300 only) Selected ports can be shut down when a single SFM is available on the E300 system. Each port to be shut down must be configured individually. When an E300 system boots up and a single SFM is active this configuration, any ports configured with this feature will be shut down. All other ports are booted up. Similarly, if an SFM fails (or is removed) in an E300 system with two SFM, ports configured with this feature will be shut down. All other ports are treated normally. When a second SFM is installed or replaced, all ports are booted up and treated as normally. This feature does not take affect until a single SFM is active in the E300 system. Disable port on one SFM This feature must be configured for each interface to shut down in the event that an SFM is disabled. Enter the command disable-on-sfm-failure from INTERFACE mode to disable the port when only a single SFM is available. 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 state or flaps, routing protocols are notified of the status of the routes that are affected by the change in state, and these protocols go through momentous task of re-converging. Flapping therefore puts the status of entire network at risk of transient loops and black holes. Link dampening minimizes the risk created by flapping by imposing a penalty for each interface flap and decaying the penalty exponentially. Once the penalty exceeds certain threshold, the interface is put in an "error-disabled" state, and for all practical purposes of routing, the interface is deemed to be "down." Once the interface becomes stable and the penalty decays below a certain threshold, the interface comes up again and the routing protocols re-converge. Link dampening: • reduces processing on the CPUs by reducing excessive interface flapping. • improves network stability by penalizing misbehaving interfaces and redirecting traffic • improves convergence times and stability throughout the network by isolating failures so that disturbances are not propagated. Important Points to Remember • Link dampening is not supported on VLAN interfaces • Link dampening is disabled when the interface is configured for port monitoring 406 | Interfaces