QoS/GoS Routing in Optical Networks

1. QoS/GoS Routing in Optical Networks NOBEL WP2 Meeting, Berlin 18-19 May 2004

2. QoS/GoS Routing in Optical Networks • A2.2 - Study of traffic engineering concepts for end-to-end broadband services for all • Route Management Area • Traffic modelling and Characterization • QoS aspects „To study new methods for route management (intra- and inter-domain), so that the QoS performance figures are taken into account in the routing decisions.” NOBEL WP2 Meeting, Berlin 18-19 May 2004

3. Objectives • Formulation of the o–SLS • Algorithms that will perform route computation and wavelength assignment according to the o-SLS • Environment • on-demand service • lightpath requests (digital service) • no wavelength conversion • arbitrary topologies NOBEL WP2 Meeting, Berlin 18-19 May 2004

4. Classification of parameters • Grade of Service (GoS) • Provisioning parameters • Quality of Service (QoS) • analog parameters • digital parameters • Quality of Resilience (QoR) NOBEL WP2 Meeting, Berlin 18-19 May 2004

5. Survey of the potential service parameters in optical network • GoS parameters • connection setup time • connection tear-down time • blocking probability • Provisioning parameters • client signal format • minimum lease time (holding time) • maximum lease time (holding time) • maximum number of connections (per user) NOBEL WP2 Meeting, Berlin 18-19 May 2004

6. Survey of the potential service parameters in optical network • QoS digital parameters • BER • routing stability (probability that the working path is rerouted) • latency • latency variation (jitter) • forced tear-down probability • QoR parameters: • service availability • recovery time • maximum outage time • route differentiation (SRLG) • blocking probability of restoration NOBEL WP2 Meeting, Berlin 18-19 May 2004

7. Routing and Wavelength Assignment • Lightpath request: NX->NY • Two main tasks: • choose route • assign wavelength • Maximize resources for future (unknown) requests • Minimize overall blocking probability • Choice • predetermined • dependent on network state NOBEL WP2 Meeting, Berlin 18-19 May 2004

8. Routing and Wavelength Assignment • Tasks may be done sequentially, or simultaneously • Metrics/weights • hop count • number of free wavelengths on a link • number of continuous free wavelengths on a path • Centralised vs. distributed control • inaccurate network state information • resource allocation collisions NOBEL WP2 Meeting, Berlin 18-19 May 2004

9. Routing Fixed Shortest Path Alternate k-shortest path k disjoint shortest path Least Congested Path Least Loaded Adaptive with precalculated paths Wavelength Assignment Random First Fit Incr/Decr Most Used Least Used Least Loaded Min Sum Max Sum RCL/DRCL Wavelength Reservation Routing and Wavelength Assignment NOBEL WP2 Meeting, Berlin 18-19 May 2004

10. GoS Routing Strategies • Resource reservation • local • global • Forced Tear-down • Alternate Paths • Reserve and Wait • Rerouting NOBEL WP2 Meeting, Berlin 18-19 May 2004

11. A A A-B Lightpath request (bronze) OXC C OXC OXC Trying shortest path... OXC OXC No resources... OXC OXC OXC B B OXC D Alternate Paths Explained (bronze request) Request blocked. NOBEL WP2 Meeting, Berlin 18-19 May 2004

12. A A A A-B Lightpath request (silver) OXC OXC C C OXC OXC OXC Trying shortest path... OXC OXC OXC OXC No resources... Trying alternate path... OXC OXC OXC OXC OXC B B B OXC OXC D D Alternate Paths Explained (silver request) Lightpath established. NOBEL WP2 Meeting, Berlin 18-19 May 2004

13. A A A A A-B Lightpath request (gold) OXC OXC OXC C C C OXC OXC OXC OXC Trying shortest path... OXC OXC OXC OXC OXC OXC No resources... Trying alternate path... OXC OXC OXC OXC OXC OXC OXC No resources... (silver req. would be blocked) B B B B Searching other paths... OXC OXC OXC D D D Alternate Paths Explained (gold request) Lightpath established. NOBEL WP2 Meeting, Berlin 18-19 May 2004

14. GoS Routing Strategies • Resource reservation • local • global • Forced Tear-down • Alternate Paths • Reserve and Wait • Rerouting NOBEL WP2 Meeting, Berlin 18-19 May 2004

15. Analysis of the proposed scenarios • strengths and weaknesses • computational complexity • control plane requirements • lightpath set-up time • forced tear-down probability • qualitative and quantitative analysis NOBEL WP2 Meeting, Berlin 18-19 May 2004

16. Current focus • Blocking probability is a prime concern • Our current focus: • consider only blocking probability • consider networks with centralized control • Other QoS/GoS/QoR parameters are left for further study NOBEL WP2 Meeting, Berlin 18-19 May 2004

17. Summary • o-SLS parameters • GoS Routing Strategies • Discussion of the proposed scenarios NOBEL WP2 Meeting, Berlin 18-19 May 2004

18. References • M. Fawaz, B. Daheb,O. Audouin, M. Du-Pond, G. Pujolle, „Service level agreement and provisioning in optical networks,” IEEE Communications Magazine, Vol.42, Iss.1, Jan. 2004 • P. Castoldi et al., „Definition of Network Management and Control requirements of network scenarios and solutions supporting Broadband Services for All,” Nobel Deliverable D2, May 2004 • H. Zang, J. P. Jue, B. Mukherjee, „A review of routing and wavelength assignment approaches for wavelength-routed optical WDM networks,” Optical Networks Mag., Vol. 1 no. 1, Jan. 2000, • S. Xu, L. Li, and S. Wang, „Dynamic routing and assignment of wavelength algorithms in multifiber wavelength division multiplexing networks,” IEEE Journal Selected Areas in Comm., vol. 18, pp. 2130-2137, Oct. 2000 • J. Spaeth, „Dynamic routing and resource allocation in WDM transport networks,” Computer Networks 32 (2000), pp. 519 – 538, May 2000. • Y. Yoo, S. Ahn, C. S. Kim, „Adaptive Routing Considering the Number of Available Wavelengths in WDM Networks,” IEEE Jourcal on Selected Areas in Communications, vol. 21, no. 8, Oct. 2003 NOBEL WP2 Meeting, Berlin 18-19 May 2004