Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.100.0 - Page 335
Hitless Behavior, a Stack Unit Slot, Removing a Provisioned Logical Stack Unit
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Pre-Configuring a Stack Unit Slot You may also pre-configure an empty stack unit slot with a logical stack unit. To pre-configure an empty stack unit slot, use the following command. • Pre-configure an empty stack unit slot with a logical stack unit. CONFIGURATION mode stack-unit unit_id provision S4820T Example of Viewing a Logical Configuration of a Pre-Configured Stack Unit After creating the logical stack unit, you can configure the interfaces on the stack unit as if it is present. Dell#show system stack-unit 1 -- Unit 1 -Unit Type Status : Member Unit : not present Dell#con Dell(conf)#stack-unit 1 provision S4820T Dell(conf)#end Dell#show system stack-unit 1 -- Unit 1 -Unit Type Status Required Type : Member Unit : not present : S4820T - 52-port GE/TE/FG (SE) Dell# Dell(conf)#interface tengigabitethernet 1/0 Dell(conf-if-te-1/0)# Removing a Provisioned Logical Stack Unit To remove the line card configuration, use the following command. • To remove a logical stack-unit configuration, use the following command: CONFIGURATION mode no stack-unit unit_id provision Hitless Behavior Hitless is a protocol-based system behavior that makes a stack unit failover on the local system transparent to remote systems. The system synchronizes protocol information on the Management and Standby stack units such that, in the event of a stack unit failover, it is not necessary to notify the remote systems of a local state change. Hitless behavior is defined in the context of a stack unit failover only. • Only failovers via the CLI are hitless. The system is not hitless in any other scenario. Hitless protocols are compatible with other hitless and graceful restart protocols. For example, if hitless open shortest path first (OSPF) is configured over hitless the link aggregation control protocol (LACP) link aggregation groups (LAGs), both features work seamlessly to deliver a hitless OSPF-LACP result. However, to achieve a hitless end result, if the hitless behavior involves multiple protocols, all protocols must be hitless. For example, if OSPF is hitless but bidirectional forwarding detection (BFD) is not, OSPF operates hitlessly and BFD flaps upon an RPM failover. The following protocols are hitless: High Availability (HA) 335
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