Restoration Time Motivation, "Requirements"

[Dave McDysan <dave.mcdysan@wcom.com>]

In response to my action from today.

Dave

There are two types of restoration/protection mechanism: local and path.
Since local restoration/protection responds to locally detected faults and
need only take local actions, presumably this can occur more rapidly than
path-based restoration/protection that requires exchange of signaling
messages between two or more nodes.

Voice over IP is an application driver for the amount of time allocated to a
restoration/protection action. An interruption of 50 ms in the playback of
voice is not perceivable to a person, while an interruption of a second or
so will likely result in a person hanging up. If the network is supporting
TDM, then an outage of 2+/-0.5 seconds will result in TDM alarms. Based upon
the VoIP application, the objectives for restoration/protection switching
are as follows:

Local: 0-50 ms
Path: 500-2000 ms