Background: Know: Recognize: MTTR





Types and levels of redundancyEdit

There are three types of the standby devices: cold, warm and hot.

Cold: It is the state when the devices are turned off and in this state the devices can not protect the state information but can protect the hardware.

Warm: In warm state, the devices have already been powered up, but have not been configured. It is similar to cold type, which can protect the hardware but can not protect the state information. what is more, the mean time to restore/recovery(MTTR ) can be reduced.

Hot: It is a powered up and fully configured state of the devices. Both the hardware and state information can be protected.

There are two types of redundancy planning which are critical for the provisioned networks, such as MPLS .

1+1-- one backup will be used when one primary is in use.

1:1-- the backup will only be used when the primary fails.

==See also==

Corresponding TELE9752 lecture slide

Hot Standby Router Protocol (HSRP)

Wikipedia article