OSA's Digital Library

Optics Express

Optics Express

  • Editor: Andrew M. Weiner
  • Vol. 21, Iss. 5 — Mar. 11, 2013
  • pp: 5481–5486
« Show journal navigation

Experimental assessment of dynamic integrated restoration in GMPLS multi-layer (MPLS-TP/WSON) networks

Ricardo Martínez, Ramon Casellas, and Raül Muñoz  »View Author Affiliations


Optics Express, Vol. 21, Issue 5, pp. 5481-5486 (2013)
http://dx.doi.org/10.1364/OE.21.005481


View Full Text Article

Acrobat PDF (990 KB)





Browse Journals / Lookup Meetings

Browse by Journal and Year


   


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools

Share
Citations

Abstract

We present the implementation of the GMPLS control plane functions and path computation algorithm deployed within the CTTC ADRENALINE testbed for the dynamic integrated restoration in multi-layer (MPLS-TP over WSON) networks. The experimental assessment is conducted in terms of the blocking probability, path computation time, restorability and restoration time.

© 2013 OSA

1. Introduction

The integration of both packet switching (Multi-Protocol Label Switching – Transport Profile, MPLS-TP) and optical circuit switching (Wavelength Switched Optical Networks, WSON) in a multi-layer network (MLN) is a candidate solution to attain a more cost/energy-efficient and scalable transport network infrastructure offloading the IP convergence layer. To fully leverage the benefits of combining both layers (i.e., MPLS-TP bandwidth flexibility/granularity and WSON transport capacity) a GMPLS unified control plane (UCP) is adopted. The UCP allows deploying MLN Traffic Engineering (TE) strategies [1

1. E. Oki, K. Shiomoto, D. Shimazaki, N. Yamanaka, W. Imajuku, and Y. Takigawa, “Dynamic multilayer routing schemes in GMPLS-based IP+optical networks,” IEEE Commun. Mag. 43(1), 108–114 (2005). [CrossRef]

]. The TE functions are the processes for optimizing the performance of a telecommunications network by dynamically analyzing, predicting and regulating the traffic flows being transported throughout the network. In general, these functions are conceived to attain the most optimal/efficient use of the global network resources. In a MLN context, the purpose of TE strategies (grooming [1

1. E. Oki, K. Shiomoto, D. Shimazaki, N. Yamanaka, W. Imajuku, and Y. Takigawa, “Dynamic multilayer routing schemes in GMPLS-based IP+optical networks,” IEEE Commun. Mag. 43(1), 108–114 (2005). [CrossRef]

]) is to merge/group low data rate and flexible higher-layer connections (e.g., Packet Switch Capable, PSC connections) with small bandwidth requirements into new or already established high data rate lower-layer connections with coarse bandwidth (i.e., Lambda SC, LSC tunnels). In other words, network resources at the lower-layer LSPs (e.g., bandwidth, ports) can be efficiently reused when dynamically provisioning and restoring higher-layer LSPs. To this end, each node has a unified vision of the topology and resources in all the layers, gathered in the TE Database, TED.

Despite several works have proposed efficient MLN restoration strategies [2

2. P. Chołda and A. Jajszczyk, “Recovery and its quality in multilayer networks,” J. Lightwave Technol. 28(4), 372–389 (2010). [CrossRef]

,3

3. X. Cui, J. Wang, X. Yao, W. Liu, H. Xie, and Y. Li, “Optimization of multilayer restoration and routing in IP-over-WDM networks,” in National Fiber Optic Engineers Conference (NFOEC), NWD3 (2008).

], the restoration performance within an experimental GMPLS UCP is nonexistent. Thus, the objective of this work is twofold: firstly, to present the GMPLS UCP and path computation algorithm for the integrated restoration in MLN; secondly, to experimentally evaluate its performance within the CTTC ADRENALINE testbed in terms of blocking, restoration time and restorability.

2. GMPLS UCP for integrated restoration

  • a. After the failure is detected, the upstream node (LSR8) adjacent to the link failure must convey the notification process, that is, for each disrupted optical connection or LSC LSP, a RSVP-TE Notify message is sent to the ingress node of such optical tunnels, carrying specific link failure information (failed link 8-7). This step is crucial to allow the restoration process computing a path disjoint to the failed link. Furthermore, an OSPF-TE link state update (LS_Upd1) needs to be flooded in order to update nodes TED about the failed link.
  • b. Once the Notify message reaches the LSC LSP ingress node (LSR1), a break-before-make strategy is applied, where the failed optical tunnel (w_LSC_LSP) is firstly torn down using the RSVP-TE Path Tear message. By doing so, the wavelength channels occupied on the links traversed by the failed connection are released. Consequently, the TE link attributes (e.g., bandwidth and wavelength channel status) associated to those links is updated (i.e., LS_Upd2, LS_Upd3 and LS_Upd4).

  • c. At this step, the integrated restoration path computation is triggered at the ingress LSR1 to set up the restoration of the interrupted PSC LSPs (r_PSC_LSP). The input for the restoration path computation is the topology graph constructed from the gathered TED as well as the information carried into the received Notify message (i.e., blocked FA TE link).

  • d. Finally, the r_PSC_LSP is established though the new PSC FA TE link whose available bandwidth is then updated (LS_Upd11).

3. MLN working / restoration path computation

  • An LSP must be initiated and terminated on the same switching capability [4

    4. K. Shiomoto, D. Papadimitriou, J. L. Le Roux, M. Vigoureux, and D. Brungard, “Requirements for GMPLS-based multi-region and multi-layer networks (MLN/MRN),” IETF RFC 5212 (2008), http://tools.ietf.org/html/rfc5212

    ].
  • A path may traverse one or more lower switching layers but the correct adaptation among them must be guaranteed following the GMPLS hierarchy [7

    7. K. Kompella and Y. Rekhter, “Label switched paths (LSP) hierarchy with generalized multi-protocol label switching (GMPLS) traffic engineering (TE),” IETF RFC 4206 (2005), http://tools.ietf.org/html/rfc4206

    ].
  • The eligible and candidate TE links to form the selected path must have unreserved bandwidth equal or larger than the bandwidth demanded by the LSP request.
  • For the restoration path, once the SRLGs of the excluded link are resolved the computed path excludes any link tied to these SLRGs.

For both working and restoration paths, all the optical sub-paths constituting the route are subject to the wavelength continuity constraint, which is addressed by RSVP-TE signaling.

4. Experimental performance assessment

The performance metrics of interest are: for the working path, the path computation time, the setup delay (contribution from both path computation time and end-to-end signaling process), and the connection blocking probability (BP); for the restoration path, the restoration path computation time, the restoration time and the restorability. The latter is defined as the ratio between the successfully restored PSC LSPs and the total failed PSC LSPs.

Last but not least, it is worth observing that the restoration time increases around 25-34 ms with respect to the working setup delay. Such a significant increase is due to three factors: the notification process, the restoration path computation and the signaling process. The process of notifying each source node of the failed optical connection affects the overall restoration time. On the other hand, from Table 1, we observe that the restoration path computation is, on average, more time consuming compared to the computation of the working path. The reason behind this is the application of the SRLG-disjointness constraint, which increases the time to find a feasible path. Finally, the computed restoration paths tend to traverse larger routes in hops than the working paths in order to exclude a failed link.

5. Conclusions

This work summarizes the deployed integrated restoration (GMPLS UCP and path computation) within MLN. This is experimentally assessed under dynamic traffic and failure generation using different number of PSC-LSC ports in terms of the blocking probability, path computation time, restorability and restoration time. As expected, the number of ports impacts significantly on the exploitation of the grooming, which does reduce the overall BP of working paths and increase the restorability when such working LSPs are disrupted.

The deployment and use of the presented GMPLS-based integrated restoration scheme to nationwide networks (e.g., comprising hundreds of nodes and serving a large number of concurrent connections) basically depends on the dynamicity of both the connection demands (i.e., LSP inter-arrival and holding times) and the failure occurrences (fiat and mrp). It is expected that, even within large network scenarios, the performance of the path computation, working setup delay and restoration times is not significantly impacted as long as the connection inter-arrival time and failure events occur at the same time scale (i.e., seconds), and the network has been correctly dimensioned.

Acknowledgments

Spanish MINECO through the project DORADO (TEC2009-07995), and by the EC’s FP7 through the IP STRONGEST (247674).

References and links

1.

E. Oki, K. Shiomoto, D. Shimazaki, N. Yamanaka, W. Imajuku, and Y. Takigawa, “Dynamic multilayer routing schemes in GMPLS-based IP+optical networks,” IEEE Commun. Mag. 43(1), 108–114 (2005). [CrossRef]

2.

P. Chołda and A. Jajszczyk, “Recovery and its quality in multilayer networks,” J. Lightwave Technol. 28(4), 372–389 (2010). [CrossRef]

3.

X. Cui, J. Wang, X. Yao, W. Liu, H. Xie, and Y. Li, “Optimization of multilayer restoration and routing in IP-over-WDM networks,” in National Fiber Optic Engineers Conference (NFOEC), NWD3 (2008).

4.

K. Shiomoto, D. Papadimitriou, J. L. Le Roux, M. Vigoureux, and D. Brungard, “Requirements for GMPLS-based multi-region and multi-layer networks (MLN/MRN),” IETF RFC 5212 (2008), http://tools.ietf.org/html/rfc5212

5.

J. Moy, “OSPF Version 2,” IETF RFC 2328 (1998), http://www.ietf.org/rfc/rfc2328.txt

6.

R. Martinez, R. Casellas, and R. Muñoz, “Experimental validation / evaluation of a GMPLS unified control plane in multi-Layer (MPLS-TP/WSON) networks,” in National Fiber Optic Engineers Conference (NFOEC), NTu2J (2012).

7.

K. Kompella and Y. Rekhter, “Label switched paths (LSP) hierarchy with generalized multi-protocol label switching (GMPLS) traffic engineering (TE),” IETF RFC 4206 (2005), http://tools.ietf.org/html/rfc4206

OCIS Codes
(060.4253) Fiber optics and optical communications : Networks, circuit-switched
(060.4261) Fiber optics and optical communications : Networks, protection and restoration

ToC Category:
Backbone and Core Networks

History
Original Manuscript: September 26, 2012
Revised Manuscript: November 30, 2012
Manuscript Accepted: November 30, 2012
Published: February 27, 2013

Virtual Issues
European Conference on Optical Communication 2012 (2012) Optics Express

Citation
Ricardo Martínez, Ramon Casellas, and Raül Muñoz, "Experimental assessment of dynamic integrated restoration in GMPLS multi-layer (MPLS-TP/WSON) networks," Opt. Express 21, 5481-5486 (2013)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-21-5-5481


Sort:  Author  |  Year  |  Journal  |  Reset  

References

  1. E. Oki, K. Shiomoto, D. Shimazaki, N. Yamanaka, W. Imajuku, and Y. Takigawa, “Dynamic multilayer routing schemes in GMPLS-based IP+optical networks,” IEEE Commun. Mag.43(1), 108–114 (2005). [CrossRef]
  2. P. Chołda and A. Jajszczyk, “Recovery and its quality in multilayer networks,” J. Lightwave Technol.28(4), 372–389 (2010). [CrossRef]
  3. X. Cui, J. Wang, X. Yao, W. Liu, H. Xie, and Y. Li, “Optimization of multilayer restoration and routing in IP-over-WDM networks,” in National Fiber Optic Engineers Conference (NFOEC), NWD3 (2008).
  4. K. Shiomoto, D. Papadimitriou, J. L. Le Roux, M. Vigoureux, and D. Brungard, “Requirements for GMPLS-based multi-region and multi-layer networks (MLN/MRN),” IETF RFC 5212 (2008), http://tools.ietf.org/html/rfc5212
  5. J. Moy, “OSPF Version 2,” IETF RFC 2328 (1998), http://www.ietf.org/rfc/rfc2328.txt
  6. R. Martinez, R. Casellas, and R. Muñoz, “Experimental validation / evaluation of a GMPLS unified control plane in multi-Layer (MPLS-TP/WSON) networks,” in National Fiber Optic Engineers Conference (NFOEC), NTu2J (2012).
  7. K. Kompella and Y. Rekhter, “Label switched paths (LSP) hierarchy with generalized multi-protocol label switching (GMPLS) traffic engineering (TE),” IETF RFC 4206 (2005), http://tools.ietf.org/html/rfc4206

Cited By

Alert me when this paper is cited

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.

Figures

Fig. 1 Fig. 2 Fig. 3
 

« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited