Abstract—We develop a novel network protection scheme that
provides guarantees on both the fraction of time a flow has full
connectivity, as well as a quantifiable minimum grade of service
during downtimes. In particular, a flow can be below the full
demand for at most a maximum fraction of time; then, it must
still support at least a fraction q of the full demand. This is in contrast
to current protection schemes that offer either availabilityguarantees
with no bandwidth guarantees during the downtime,
or full protection schemes that offer 100% availability after a
single link failure. We develop algorithms that provide multiple
availability guarantees and show that significant capacity savings
can be achieved as compared to full protection. If a connection
is allowed to drop to 50% of its bandwidth for 1 out of every 20
failures, then a 24% reduction in spare capacity can be achieved
over traditional full protection schemes. In addition, for the case
of q = 0, corresponding to the standard availability constraint, an
optimal pseudo-polynomial time algorithm is presented.