Leveraging MPLS Backup Paths for Distributed Energy-Aware Traffic Engineering

Abstract

Abstract-Backup paths are usually pre-installed by network operators to protect against single link failures in backbone networks which use Multi-Protocol Label Switching (MPLS). This paper introduces a new scheme called Green Backup Paths (GBP) which intelligently exploits these existing backup paths to perform energy-aware traffic engineering without adversely impacting the primary role of these backup paths of preventing traffic loss upon single link failures. This is in sharp contrast to most existing schemes which tackle energy efficiency and link failure protection separately, resulting in substantially high operational costs. GBP works in an online and distributed fashion where each router periodically monitors its local traffic conditions and cooperatively determines how to reroute traffic so that the highest number of physical links can go to sleep for energy saving. Furthermore, our approach maintains Quality-of-Service by restricting the use of long backup paths for failure protection only and therefore, GBP avoids substantially increased packet delays. GBP was evaluated on the Point-of-Presence representation of two publicly-available network topologies, namely GÉANT and Abilene, and their real traffic matrices. GBP was able to achieve significant energy saving gains which are always within 15% of the theoretical upper bound.

On the performance of online and offline green path establishment techniques

“…Its key ideas are to route a LSP request over paths with the minimum number of hops and instead of exhaustively exploring all paths, the algorithm searches only sub-graphs induced by active routers and links. In [27], the authors exploit pre-installed backup paths used to protect against failed links on a primary LSP. The proposed algorithm, called GBP, achieves energy saving by re-routing traffic from protected links onto these backup paths.…”

“…The objective here is to reduce energy consumption by utilizing established links and, additionally, favoring paths that require the fewest new links. Note that this approach is similar to that of [27]. Specifically, for the routing of a given (s, d) pair demand, the technique in [27] uses an existing shortest backup path.…”

“…Note that this approach is similar to that of [27]. Specifically, for the routing of a given (s, d) pair demand, the technique in [27] uses an existing shortest backup path. It aims to minimize the establishment of new links.…”

“…2. This paper presents and studies the performance of two offline and four online heuristics: i) Offline Most Overlapped (Offline-MO ) [27], a technique that aims to use paths that share the most links with past or/and future LSP requests, ii) Offline with Ratio (Offline-R ), which is similar to Offline-MO but favors paths that require fewer number of new links, iii) Online Most Overlapped (Online-MO ), which is similar to its offline counterpart, is an algorithm that uses paths that share the most links with already established links, iv) Online with Ratio (Online-R ), which is similar to Online-MO but prefers paths that involve the minimal number of new links, v) Online Minimum Hops (Online-MinH ) [28], an approach that gives priority to paths with a small number of hops, and vi) Online Random LSP (Online-R-LSP ) [29] which selects paths randomly. 3.…”

Energy-efficiency versus resilience: risk awareness view on dimensioning of optical networks with a sleep mode

“…We follow this approach in relation to rerouting, but in the case of protection methods, we assume that sleeping elements cannot be woken on demand. Francois et al [29] propose a new method that provides resilience while also aiming to use energy more efficiently. They propose the use of green backup paths to carry some traffic (so that other links can go sleep); they are used again as real backup paths when a failure happens (this resembles a preemptive mode in 1:1 automatic protection switching standardized for transport networks).…”