Scholarly article on topic 'Inter-domain Hybrid Metric as SLS Dissemination Mechanism in Green Optical Networks'

Inter-domain Hybrid Metric as SLS Dissemination Mechanism in Green Optical Networks Academic research paper on "Materials engineering"

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Procedia Computer Science
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{GMPLS / "Green Networks" / EASB / "Path Attribute"}

Abstract of research paper on Materials engineering, author of scientific article — Alireza Nafarieh, Yashar Fazili, Muhammad Hassan Raza, William Robertson

Abstract This paper introduces the dissemination of Hybrid cost calculated for each route in Emission Aware and SLA Based Routing Mechanism as path attribute for purpose of inter-domain routing operation. This paper then compares the performance of the routing mechanism using this method against performance of the routing methods using other types of transmitted metrics such as energy code.

Academic research paper on topic "Inter-domain Hybrid Metric as SLS Dissemination Mechanism in Green Optical Networks"

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Procedia Computer Science 37 (2014) 176 - 180

The 5th International Conference on Emerging Ubiquitous Systems and Pervasive Networks

(EUSPN-2014)

Inter-Domain Hybrid Metric as SLS Dissemination Mechanism in

Green Optical Networks

Alireza Nafarieh*,Yashar Fazili, Muhammad Hassan Raza, William Robertson

Dalhousie University, Internetworking program, 1360 Barrington Street, Halifax, Nova Scotia Canada, B3H 4R2

Abstract

This paper introduces the dissemination of Hybrid cost calculated for each route in Emission Aware and SLA Based Routing Mechanism as path attribute for purpose of inter-domain routing operation. This paper then compares the performance of the routing mechanism using this method against performance of the routing methods using other types of transmitted metrics such as energy code.

© 2014TheAuthors.Publishedby Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

Peer-review under responsibility of the Program Chairs of EUSPN-2014 and ICTH 2014. Keywords: GMPLS; Green Networks; EASB; Path Attribute

1. Introduction

This work introduces the dissemination of the hybrid cost calculated in [1] for Inter-domain routing operation. For green awareness in optical network it is required that the amount of energy, the source of energy and emission emitted as a result of operation of the network to be incorporated in routing decision, to use sections of the network that use less energy or use green source of energy and have lower Greenhouse gas emissions. With emission awareness the overall emission and pollution of network is reduced; however it must be decided what kind of information is needed to perform this operation itself. Different routing mechanisms use different types of information to accomplish green awareness task for Intra-domain and Inter-domain routing such as the mechanism in [2] for Intra-domain routing and the suggested approach in [3] for Inter-domain routing. This paper is organized as follows: section 2 will briefly overview the related works done in this field, section 3 will introduce the dissemination of the hybrid cost as an Inter-domain path attribute followed by section 4 that introduces the

*Alireza Nafarieh. Tel.:+1-902-494-2057 Email: ali.nafarieh@dal.ca

1877-0509 © 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.Org/licenses/by-nc-nd/3.0/).

Peer-review under responsibility of the Program Chairs of EUSPN-2014 and ICTH 2014. doi:10.1016/j.procs.2014.08.027

simulation environment used in comparing the various routing mechanisms reviewed in section 2 and 3. Section 5 draws the conclusion and states the future work.

2. Related Work

2.1. Energy Aware and SLA Based Routing Mechanism (EASB)

Energy aware and SLA Based routing mechanism in [1] uses a hybrid metric in finding a route form source of a connection request to the destination node, which is composed of length, and the emission value of the link know as Emission Factor or EF. This routing method finds the most available routes between source and destination of the connection request and then calculates a hybrid cost using balancing factor alpha for each route. The route with lowest hybrid cost that meets the SLA of the connection request serves the connection request. To calculate the amount of emission of each link and each route, EASB uses the extended Link State Advertisements (LSAs) introduced in Energy Efficient (EE) Routing Mechanism in [4] for intra-domain routing operation. This method will be called Hybrid Cost (HC) method in this paper which is the foundation of new inter-domain path attribute.

2.2. Energy Efficient Routing Mechanism (EE)

The Energy Efficient routing mechanism in [4] performs routing based on lowest energy state. This routing mechanism uses the extended Link State Advertisements introduced in [2] to disseminate the information about the type of energy powering up each section of optical network, given by smart grid. The route with minimum energy state serves the request. The method used in this work is called Energy Code (EC) in this paper.

2.3. Dynamic Inter-domain Negotiation for Green Algorithms

This routing mechanism in [3] uses the LSAs of section 2.1 to calculate the minimum emission value for each destination and within the autonomous and then disseminates the calculated information as a path attribute in interdomain routing operation. This routing mechanism is called Minimum Path Emission (MPE) in this paper.

3. Hybrid Cost as Path Attribute

This paper introduces the dissemination and communication of the Hybrid Cost (HC) used with EASB as new path attribute in a similar fashion to work in [3]. Using (HC) as path attribute simplifies the routing process by considering only one attribute for emission awareness in optical network. MPE and EE approach need two pieces of information to calculate the emission or energy state of each link namely amount of the power itself and the source or type of energy. Amount of power used by each link in one Autonomous system (AS) might not be visible to other peers in another AS. Hybrid cost combines these information in one single path attribute and communicates that with different external peers in inter-domain routing operation. This attribute is added as optional transitive path attribute to BGP routing protocol. BGP routers supporting this attribute can use it as path attribute and choose paths that have lower amount of emission.

4. Simulation

4.1. Parameters of Interest

In this part of paper usage of HC as inter-domain and intra domain routing mechanism is compared against usage of combination of EE for intra-domain and MPE for inter-domain routing mechanism in reducing the emission and utilization level of resources. The parameter for comparing the amount of emission or greenness attribute of each approach is amount of Co2 emission per unit resource lambda and the parameter for comparing the amount of utilization of resources (lambda) is called the average path length. The lower the emission per resource the greener the method and the lower the average path length the better or less resource usage in the optical network. The

combination of Hybrid Cost as intra-domain and inter-domain routing mechanism and Energy Code as intra-domain and Minimum Path Emission as inter-domain are denoted as (HC,HC) and (EC,MPE) respectively. These combinations are compared against the routing method in [5] which is not a green aware routing mechanism and has higher emission rate compared to green aware routing mechanisms. The non-green method will be called NG. The method in which path attributes are communicated in routing mechanism of [5] is not discussed here. In this paper SLA parameter is the requested route availability for the lightpath. The third criteria of comparison in simulation is the SLA satisfaction ratio which is the ratio of the number of connection requests that served with a route that met the SLA of request to the total number of served connection requests.

4.2. Environment

Simulation environment is the network of NSFnet with 14 nodes and 21 bidirectional links that have been separated in to 3 distinct autonomous systems of A, B and C. Each link has 128 wavelength (lambdas) and first fit is used for resource allocation. The numbers on the links represent the node separation in units of km. This network operates without continuity constraint for wavelengths. Connection request arrivals and durations follow a Markovian process and are exponential distributed with mean of 10 requests per hour and 6 hours respectively. The amount of load is defined as the product of arrival rate and duration based on [6]. The change in source of energy powering up different sections of the network is called emission topology change and is fixed to 6 hours in this simulation.

4.3. Simulation Results

This section details the results for simulation of parameters of interest. Fig 2. Shows the emission reduction or greenness of two combinations of (EC, MPE) and (HC, HC) against NG method which is not a green routing mechanism. As expected (based on results of previous work in [1]) and seen here (EC, MPE) has a better reduction in emission and emits close to 50% less pollution compared to NG followed by (HC,HC) pair that reduces the emission by 15% however since (HC,HC) is a hybrid method it is expected to reduce the resource utilization by reducing the average route length. Fig 3. Shows that (HC, HC) method indeed has significantly better (lower) resource utilization. (HC, HC) is about 30% more resource efficient compared to (EC,MPE) method followed by NG. Lower resource utilization is translated to less required resources for the same number of connection requests to save capital for ISPs or the same amount of resources for more number of connection requests for increased revenue. Fig 4 graphs the SLA satisfaction ratio for two combinations and the NG method. Since (HC,HC) routing mechanism considers the most available routes (The same as NG) in calculation of hybrid costs, it serves the requests with most available routes that have higher chance of meeting and exceeding the SLA of the connection

Fig 1. NSFnet network in three Autonomous Systems

request. Therefore (HC,HC) and NG method have the highest (100%) satisfaction ratio which is 10% higher than (EC,MPE) method.

Emission per Lambda

Fig 2. Average Emission per unit resource

Average Lambda Per connection

Fig 3. Average path length

Average SLA Satisfaction rate

Fig. 4 SLA satisfaction ratio

5. Conclusion

It can be concluded that hybrid method can be used to reduce the emission of the network as well as optimizing the amount of resource utilization. The contribution of this paper added inter domain routing support to the EASB routing mechanism by transmitting the calculated hybrid cost for each destination as path attribute.

References

1. Y. Fazili, A. Nafarieh, B. Robertson, Hybrid Energy-aware and SLA-based Routing Mechanism over Optical Networks, Procedia Computer Science, vol. 19, pp. 1151-1158, IWSRON 2013

2. J wang, S. R., OSPF-TE Extensions for Green Routing in Optical Networks. 2012 17th Opto-Electronics and Communications Conference (p. 2). Busan: IEEE, 2012

3. A. Nafarieh, Y. Fazili, W. Phillips, Dynamic Inter-domain Negotiation for Green Algorithms in Optical Networks, EUSPN 2013

4. J. Wang, S. R., Green-Aware Routing in GMPLS Networks. ICNC workshop, 2012

5. A. Nafarieh, B. Robertson, W. Phillips, and S. Sivakumar, Dynamic SLA Negotiation Mechanism in Support of Priority-aware Algorithms in Shared Mesh Optical Networks, vol. 2, pp. 324-328, ICINC 2010

6. Leon Garcia and I. Widjaja, Communication Networks Fundamental Concepts and Key Architectures, Mc Graw Hill, 2004.