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E2 Deliverable VD-M.3 Draft 1c

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    Deliverable VD-M.3

    Metro Networks - The ePhoton-ONe View

    Draft 1

    VD-M: “Metro Networks: Technologies, Architectures, and

    Protocols”

    FP6-027497 e-Photon/ONe

    NoE

    ”Optical Networks: Towards Bandwidth Manageability

    and Cost Efficiency”Project number / name:FP6-027497 / e-Photon/ONe

    Operative Commencement Date:March 1, 2006

    End of Contract:Feb 28, 2008

    Document number:

    Title of Deliverable:

    Delivery Date Planned / Preparation Date:M18/ 20.12.2007

    Task leader:Telenor R&I

    Editor:Evi Zouganeli

VD-M Metro Networks: Technologies, Architectures, and Protocols

    D.VD-M.3Metro Networks - The ePhotonONe View

    Abstract:

    Key words:

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VD-M Metro Networks: Technologies, Architectures, and Protocols

    D.VD-M.3Metro Networks - The ePhotonONe View

    Authors (TO BE UPDATED) [in red and blue contributors so far

    in D.VD-M.3]

    Giorgio Maria Tosi BeleffiISCOM

    Tibor Cinkler BME

    Filippo CuginiSSSUP

    Franco CurtiISCOM

    Jan DerkaczAGH

    Jerzy DomzalAGH

    Jorge Finochietto PoliTo

    Davide ForinISCOM

    Gerald FranzlTUW

    Philippe GraveyGET-ENST Bretagne

    David LarrabeitiUC3M

    András KernBME

    Ton Koonen TUe

    Isaías Martínez UC3M

    Francesco MateraFUB

    István MoldovánBME

    Michel MorvanGET-ENST BretagneIdelfonso Tafur Monroy TUe

    Paulo Monteiro IT

    Fabio Neri PoliTo

    Piotr PacynaAGH

    Mario PickavetIBBT

    Bart PuypeIBBT

    Luca ReaFUB

    Namik SengezerBilkentIgnacio SotoUC3M

    Inge Einar Svinnset Telenor

    Stefano Taccheo PoliMi

    Antonio TeixeiraIT

    Krzysztof WajdaAGH

    Rafal WatzaAGH

    Lena Wosinska KTH

    D.VD-M.3p. 3 of 58

VD-M Metro Networks: Technologies, Architectures, and Protocols

    D.VD-M.3Metro Networks - The ePhotonONe View

    Ni Yan TUe

    Evi ZouganeliTelenorEditor

    D.VD-M.3p. 4 of 58

VD-M Metro Networks: Technologies, Architectures, and Protocols

    D.VD-M.3Metro Networks - The ePhotonONe View

    1Introduction

    VD-M covers metro networks: technologies, architectures and protocols. Metro networks are characterised by close proximity to the traffic sources leading to a relatively low level of traffic aggregation and resulting in large pattern variations throughout the day. Flexibility in resource allocation and the possibility to reuse the available resources are central characteristics. Cost efficiency is an important aspect when considering solutions for this part of the network. In addition, the availability of a large number of services and interfaces is a challenge for a network operator/ service provider that wishes to cover a wide range of service needs. This large range of services is available via different types of access technologies and access media that may be fixed or mobile/ wireless. Seamlessness across access drop technology - at any time, any location and terminal - is another important characteristic of the metro area that is becoming more and more central.This report gives a concise overview of the ePhotonONE view on viable metro network solutions, architectures, protocols and technologies; existing, emerging and future.

    to be updated and extended

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VD-M Metro Networks: Technologies, Architectures, and Protocols

    D.VD-M.3Metro Networks - The ePhotonONe View2VD-M Participants

    The following member organisations have committed to contributing in VD-M:

    Particip. Partic. Participant nameParticipant CountryRole*Numbershort name

    CO1Politecnico di TorinoPoliTOItaly CR2Alcatel Italia S.p.A.ALCATELItalyCR4Fondazione Ugo BordoniFUBItaly

    CR5Politecnico di MilanoPoliMIItalyCR6Scuola Superiore di Studi SSSUPItaly

    Universitari e di Perfezionamento S.

    Anna

    CR9Universdad Carlos III de MadridUC3MSpainCR10Universitat Politècnica de CatalunyaUPCSpainCR12Instituto de TelecomunicaçõesITPortugalCR13Groupe des Ecoles des GETFrance

    Télécommunications

    CR16IBBT (Ghent University)IBBTBelgiumCR26Telenor ASATELENORNorway

    CR31Technische Universitaet Wien, TUWAustria

    Institute of Broadband

    Communications

    CR32Akademia Gorniczo-HutniczaAGHPolandCR33Budapest University of Technology BMEHungary

    and Economics

    CR35Research and Education Society in AITGreece

    Information Technologies

    CR40Bilkent UniversitesiBILKENTTurkey

    ISCOMItaly

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    D.VD-M.3Metro Networks - The ePhotonONe View

    3Future requirements for metro

    (a couple of pages)

    3.1Impact of future broadband access on metro network architecture

    (ENST, FUB)

    Access Network context

    The continuous increase of the access capacity proposed by the operators to their customers has

    become a major trend of telecommunications networksBroadband access has become a realityin the

    past couple of years. The development rhythm pace of the access network and the chosen associated

    technological options solutions are rather differentvary considerably from one country to another,

    with a park of existing broadband accesses dominated by cable or ADSL and planned developments focusing on FTTH or hybrid solutions such as VDSL.

    In spite of this diversity, it is now clear that the numbers of connected FTTH subscribers will increase

    dramatically during the next years, even in Europe where deployments of optical fibre in the access network has been until now quite limited compared to North-America and Asia.

    HDTV

    In that this context the question of the bit rate required to satisfy the client needs has been (and will be) the subject of many discussions. Present commercial offers of the operators proposing FTTH lie in the 50-100 Mbit/s range for the downstream channel. This is quite enough to 2 HD channels, high-speed Internet, VoIP, video-telephony, on-line gaming and one may ask whether further bandwidth will be necessary. One can first answer to this objection by noting that the average access network bandwidth is following an exponential growth (~50%/year) and there is no sign of inflection of this growth. Other arguments can be found by considering the trend towards higher definition images (with the take-off of HD-compatible TVs and the development of super HD standard, video walls, 3-D imaging) and also the amount of digital data that each user may be willing to share and to save externally. In that context commercial 1 Gbit/s access offers should be likely announced in the next couple of years.

    High definition TV will be one of the services that require the highest performance in the IP network.

    In particular many changes will be needed in the access network, with the necessity of a user

    transmission with a capacity higher than 20 Mbit/s, at least in downstream, but also in the edge and

    core with techniques to guarantee the QoS. We believe that High Definition TV will push the

    transition from copper to Fiber to the building/home (FTTB/H) access architectures.Nowadays a 20 Mbps bandwidth for the end user with the new ADSL2+ connection gives the basis

    for the development of the IP HDTV service that actually is a SAT communications prerogative. A Digital HDTV signal requires at least a bandwidth of 15 Mbps. So this kind of service is hungry of

    network resources from two points of view: backbone and access. The difference of contents, with

    high variability of the traffic, could create a lot of problems to real time services like IP HDTV and

    the techniques to assure the Quality of Service (QoS) will assume a basic role, in order to good

    manage this kind of service. A right forward priority for IP packets in fact ,will be useful to guarantee

    conditions required in term of delay and jitter.

    The main standard for HD television is 1920x1080i 16/9 that for MPEG2 means 20 Mbit/s average,

    29.97 fps, 80MB per 62000 pks IP.

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    D.VD-M.3Metro Networks - The ePhotonONe View

    Another important issue aspect is the evolution of the traffic nature. In particular the observations 1 reveal that when the made on different panels of users in different French FTTH deployment sites

    technology allows it, the traffic presents a rather symmetrical behavior (in fact, in some cases the upstream traffic exceeds exceeded the downstream one). This point is important for the access and

    metro network design as the symmetrical traffic is more demanding in terms of transmission capacities. More generally this confirms the intuition intuitive notion that users can may find their

    ways to fill utilize the available bandwidth once it becomes available.

    Impact on Metro network capacity

    A first key impact of the evolution of the broadband access network on metro network architecture is the required capacity. This point has been addressed in the framework of the “Traffic Engineering and Topology Design Joint Activity” in ePhotonONe and results were have been presented in the first

    VD-M Technical Report.

    In the following weWe here just briefly summarize the method used to estimate the capacity of future metro/access and metro/core rings and recall revisit the main conclusions. We started from simple

    service assumptions (one P2P video file transfer / day for 30% of the clients) and traffic models (Erlang B analysis). The access and metro network geographical data were derived from a realistic European operator network. The total number of clients connected to the metro network was 1.4 million. We evaluated the capacity of the metro rings as a function of the file transfer bit rate and the location of traffic concentration functions. For the metro/access ring, the required capacity is about 60 to 70 Gb/s in the most favorable case (two concentration levels) while it may exceed 100 Gb/s when concentration is only performed at the Access node. For the core ring this capacity is about 200 to 250 Gb/s in the most favorable case (two concentration levels) while it may exceed 350 Gb/s when concentration is only performed at the Access node. These estimations suggest that in the context of a wide extension of FTTH access technologies, both metro/core and metro/access rings will rely on DWDM transmission techniques rather than on CWDM.

    The above results correspond to a capacity between 140 and 275 kbps per client connected to the ring. This can be compared with the assumption of 50 kbps per client made for today networks by the French regulatory authority in a document issued in January 2007 [1].

    A more specific dimensioning study was has been carried out, also within the “Traffic Engineering

    and Topology Design Joint Activity” and presented at the RONEXT Conferencesame Joint Activity in

    VD-M . This study was based on the example of a 10 node network located in the city of Lyons, France. Two main scenarios for the average client load were studied, namely 500 kbps, in line with our previous results, and 10 Mbps, corresponding to a more aggressive assumption. The topology design of the metro network was optimized according to a cost function and an ILP-based technique. This analysis shows that a meshed topology is more advantageous than a ring one even in the 500 kbps scenario (when protection is taken into account).

    Impact on Metro network architecture

    The previous resultsOur analysis suggests that the increase of access network capacity could lead to a

    reconsider the widely deployed ring architectures for metro networks. In fact, the impact of access network on the metro network cannot just be expressed in terms of capacity requirements, especially

    in the context of FTTH technology.

    Indeed the use of optical fiber in the access network enables not only to increase dramatically the capacity offered to each client but also to increase the distance between the access network reach. 1 This information has been collected from various presentations given on a FTTH colloquium in Lannion, France on November 20, 2007.

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    Commercial PON already provides fiber lengths up to 20 km between the Central Office and the client and many laboratories are working on the introduction of cost-effective optical amplification techniques to increase both PON splitting ration and operation distance.

    This will offer to the operators an opportunity to reduce significantly the number of central offices and the corresponding OPEXOpEx. In that context, a fusion on access and metro/access networks could be envisioned. Obviously a further analysis of the target architecture and on migration scenarios is necessary to assess the benefits of such an evolution. These studies will need a close collaboration between research groups working in access and metro network fields.

    References

    [1] http://www.art-telecom.fr/fileadmin/reprise/dossiers/modeles-couts/quest-model-cout-

    collecte-consult-0107.pdf (in French, see page 5).

    [2]Design of Reliable Metro Core Networks”, P. Castoldi, F. Cugini, P. Ghelfi, L. Valcarenghi

    G. Franzl, P. Gravey, M. Morvan, L. Rea, F. Matera, and K. Wajda., RONEXT conference,

    Rome (2007)

    3.1.1HDTV (FUB)

    High definition TV will be one of the services that require the highest performance in the IP network.

    In particular many charges will be needed in the access network, with the necessity of a user

    transmission with a capacity higher than 20 Mbit/s, at least in downstream, but also in the edge and

    core with techniques to guarantee the QoS. We believe that High Definition TV will push the

    transition from copper to Fiber to the building/home (FTTB/H) access architectures.Nowadays a 20 Mbps bandwidth for the end user with the new ADSL2+ connection gives the basis

    for the development of the IP HDTV service that actually is a SAT communications prerogative. A Digital HDTV signal requires at least a bandwidth of 15 Mbps. So this kind of service is hungry of

    network resources from two points of view: backbone and access. The difference of contents, with

    high variability of the traffic, could create a lot of problems to real time services like IP HDTV and

    the techniques to assure the Quality of Service (QoS) will assume a basic role, in order to good

    manage this kind of service. A right forward priority for IP packets in fact ,will be useful to guarantee

    conditions required in term of delay and jitter.

    The main standard for HD television is 1920x1080i 16/9 that for MPEG2 means 20 Mbit/s average,

    29.97 fps, 80MB per 62000 pks IP.

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    D.VD-M.3Metro Networks - The ePhotonONe View

    4 Transport

    (Main focus: what is this, main features, status, advantages, disadvantages, main area of application; max one page per technology)

    4.1Intro – trend towards Ethernet based services ++ (FUB)

    Telecom operators and service providers are moving towards networks employing Ethernet [x],

    Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) [x], and IP technologies

    [x]. In this environment a more specific interest is for routing techniques with labelling at level “2” (L2) with a role for Ethernet considered as a specific Carrier approach. Carrier Ethernet services built on the Ethernet Line (E-Line) and Ethernet LAN (E-LAN) service types, defined by the Metro Ethernet Forum (MEF) [x], are getting more and more methods to satisfy the requirements of both residential and enterprise customers with a good compromise between cost and Quality of Service (QoS) [x]. Furthermore most of the the limiting factors of Ethernet technology in terms of Operation, Administration and Maintenance (OA&M) features, such as fault detection and recovery [x], have

    been solved permitting high reliable networks.

    Among the L2 technique VPLS is now a very appealing technique for its simplicity, scalability and overall for its multicast properties; but enormous interest, just in terms of transport functionalities, are in T-MPLS and in the novel approach of the PBT.

    According to this L2 operations for metro network the evolution could be very strong, especially from the architectural point of view, since several functions, that currently are performed only by routers, could be obtained by means of simpler and chipper switches, with enormous advantages for new operators that have to build the own network, but also for incumbents that have to improve their performance. Transport from SDH to Ethernet up to all optical novel techniques is the evolution that metro networks will experience in the next ten years.

    Aim of this paragraph is an overview about the main transport techniques and in particular on novel SDH, OTN, Ethernet with particular emphasis for VPLS, T-MPLS, PBT up to optical packet switched (and other).

    4.2NG-SDH (ENST)

    The synchronous digital hierarchy (SDH) is a physical layer circuit based synchronous protocol originally designed for TDM traffic and especially voice. It is of course able to handle data traffic but only on a synchronous basis, thus resulting in some bandwidth waste. Furthermore, the 4 by 4 multiplexing hierarchy of PDH and SDH do not fit to most data flows and especially Ethernet PHY ones. The new generation SDH (NG-SDH) has then been designed to make SDH much more adapted to data traffic by introducing flexibility in the bandwidth management of SDH circuits. NG-SDH can be summarized in three new add-on features to the SDH, giving best results when working together: the first feature is Virtual Concatenation (VCAT), the second one is Link Capacity Adjustment Scheme (LCAS) and the third one is Generic Framing Procedure (GFP).

    Virtual Concatenation is certainly the most fundamental feature of NG-SDH. This type of concatenation is called virtual in opposition with contiguous concatenation traditionally used in SDH. Contiguously concatenated SDH Virtual Containers (VCs) are physically transmitted as one big VC through the network, possibly causing bandwidth allocation problems. Furthermore, as the number of contiguously concatenated VCs has to be a power of 4, the bandwidth is not easily scalable. So, virtual concatenation allows bundling as many VCs of the same kind as needed in a Virtual Concatenation Group (VCG). As an example, a 100 Mbit/s Ethernet PHY can be put into 2 virtually concatenated 50 Mbit/s VC3s (i.e. a VC-3-2v) instead of using a single but too large 155 Mbit/s VC-4 for which there is a bandwidth waste of 33%. Furthermore, this VCG can be split at the start point and D.VD-M.3p. 10 of 58

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