In this paper, we propose a framework to reduce the aggregate power
consumption of an Autonomous System (AS) using a collaborative
approach between areas within an AS. We identify the low-power paths
within non-backbone areas and then use Traffic Engineering (TE)
techniques to route the packets along the stitched paths from non-
backbone areas / backbone area to other non-backbone areas. Such low-
power paths can be identified by using the power-to-available-
bandwidth (PWR) ratio as an additional constraint in the Constrained
Shortest Path First (CSPF) algorithm. For routing the data traffic
through these low-power paths, the Inter-Area Traffic Engineered
Label Switched Path (TE-LSP) that spans multiple areas can be used.
Extensions to the Interior Gateway Protocols like OSPF and IS-IS that
support TE extensions can be used to disseminate information about
low-power paths in the respective areas (backbone or non-backbone)
that minimize the PWR ratio metric on the links within the areas and
between the areas thereby creating a collaborative approach to reduce
the power consumption.
The feasibility of our approaches is illustrated by applying our
algorithm to an AS with a backbone area and several non-backbone
areas. The techniques proposed in this paper for the Inter-Area power
reduced paths require a few modifications to the existing features of
the IGPs supporting TE extensions. The proposed techniques can be
extended to other levels of Internet hierarchy, such as Inter-AS
paths, through suitable modifications as in .
When link state routing protocols like OSPF or ISIS are used to
discover TE topology, there is the limitation that traffic engineered
paths can be set up only when the head and tail end of the label
switched path are in the same area. There are solutions to overcome
this limitation either using offline Path Computation Engine (PCE)
that attach to multiple areas and know the topology of all areas.
This document proposes an alternative approach that does not require
any centralized PCE and uses selective leaking of low-power TE path
information from one area into other areas.