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Probe schemes to simplify the physical layer model and to keep the control plane lightweight

Probe schemes to simplify the physical layer model and to keep the control plane lightweight. Scuola Superiore Sant’Anna, Pisa, Italy. Nicola Sambo (nicola.sambo@sssup.it). The work has been done in collaboration with:

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Probe schemes to simplify the physical layer model and to keep the control plane lightweight

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  1. Probe schemes to simplify the physical layer model and to keep the control plane lightweight Scuola Superiore Sant’Anna, Pisa, Italy Nicola Sambo (nicola.sambo@sssup.it) The work has been done in collaboration with: C. Pinart (CTTC, Barcelona, Spain), E. Le Rouzic (Orange Labs, Lannion, France) Workshop: Are All-Optical Networks Manageable? OFC 2010, SAN DIEGO, CA

  2. Issues: QoT models and control plane • QoT models utilized by path computation can be very complex: • large amount of information: fiber loss, ASE, CD, PMD, SPM … • interactions among physical impairments: e.g., CD and SPM (dependence by dispersion map) • are they accurate enough? • In distributed networks, protocols must disseminate (e.g., OSPF-TE) or collect (e.g., RSVP-TE) the large amount of information, which has to be combined to estimate lightpath QoT • Probe scheme exploiting: • simple QoT models (e.g., Equivalent Length [RFC4054] ) • simplify path computation • lighten QoT parameter dissemination • QoT measurements on probe traffic along candidate lightpath • overcome model uncertainties [RFC4054] “Impairments and Other Constraints on Optical Layer Routing”, IETF RFC 4054, 2005.

  3. Probe scheme • Utilize the Equivalent Length (EL) disseminated by OSPF-TE, e.g. EL in miliage. • Identify ranges in which the model is confident • In the critical range: verify QoT on probe traffic AcceptableQoT Unacceptable QoT CRITICAL Lightpath EL THA THU PROBING Papers: [1] N. Sambo, F. Cugini, I. Cerutti, L. Valcarenghi, P. Castoldi, J. Poirrier, E. Le Rouzic, and C. Pinart, “Probe-based schemes to guarantee lightpath quality of transmission (QoT) in transparent optical networks", in Proc. Of ECOC 2008, Sep. 2008. [2] N. Sambo, C. Pinart, E. Le Rouzic, F. Cugini, L. Valcarenghi, and P. Castoldi, “Signaling and multi-layer probe-based schemes for guaranteeing QoT in GMPLS transparent networks", in Proc. of OFC 2009, San Diego, CA, Feb. 2009.

  4. Simulation results • Equivalent length+ probe scheme (EL+PS): search an acceptable lightpath (EL<THA), otherwise verify QoT along a critical lightpath (THA<EL<THU) • PS: always probe verification (no EL dissemination) n set up attempts Tab. Lightpath set up time [s] when probing time is TA and TB PS EL+PS Fig. Blocking probability vs. network load

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