Building power shortest inter-Area TE LSPs using pre-computed paths

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Last updated 2013-11-05 (latest revision 2013-05-04)
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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 [11]. 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.


Shankar Raman (
Balaji Venkat (
Gaurav Raina (

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