Hot Links; Forward Delay; Preemption; Fdb Update - Lenovo Flex System Fabric CN4093 Application Manual

Hot Links

Forward Delay

Preemption

FDB Update

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CN4093 Application Guide for N/OS 8.2
Hot Links provides basic link redundancy with fast recovery.
Hot Links consists of up to 200 triggers in stand‐alone mode and up to 200 triggers
in stacking mode. A trigger consists of a pair of layer 2 interfaces, each containing
an individual port, trunk, or LACP adminkey. One interface is the Master, and the
other is a Backup. While the Master interface is set to the active state and forwards
traffic, the Backup interface is set to the standby state and blocks traffic until the
Master interface fails. If the Master interface fails, the Backup interface is set to
active and forwards traffic. Once the Master interface is restored, it transitions to
the standby state and blocks traffic until the Backup interface fails.
You may select a physical port, static trunk, or an LACP adminkey as a Hot Link
interface. Only external uplink ports can be members of a Hot Links trigger
interface.
The Forward Delay timer allows Hot Links to monitor the Master and Backup
interfaces for link stability before selecting one interface to transition to the active
state. Before the transition occurs, the interface must maintain a stable link for the
duration of the Forward Delay interval.
For example, if you set the Forward delay timer to 10 seconds
(CN4093(config)#hotlinks trigger <x> forward­delay 10), the switch
will select an interface to become active only if a link remained stable for the
duration of the Forward Delay period. If the link is unstable, the Forward Delay
period starts again.
You can configure the Master interface to resume the active state whenever it
becomes available. With Hot Links preemption enabled, the Master interface
transitions to the active state immediately upon recovery. The Backup interface
immediately transitions to the standby state. If Forward Delay is enabled, the
transition occurs when an interface has maintained link stability for the duration of
the Forward Delay period.
Use the FDB update option to notify other devices on the network about updates to
the Forwarding Database (FDB). When you enable FDB update, the switch sends
multicasts of addresses in the forwarding database (FDB) over the active interface,
so that other devices on the network can learn the new path. The Hot Links FBD
update option uses the station update rate to determine the rate at which to send
FDB packets.