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Design of an Agile All-Photonic Network (AAPN) Gregor v. Bochmann School of Information Technology and Engineering (SITE) University of Ottawa Canada http://www.site.uottawa.ca/~bochmann/talks/AAPN-results Presentation at the APOC conference Wuhan, November 2007 Gregor v. Bochmann, University of Ottawa AAPN, 2007 1 Abstract Agile All-Photonic Networks (AAPN) is a Canadian research network (funded by NSERC and 6 industrial partners) exploring the use of very fast photonic switching for building optical networks that allow the sharing (multiplexing) of a wavelength between different information flows. The aim is to bring photonic technology close to the end-user in the residential or office environment. The talk gives an overview of the proposed overlaid star network architecture and describes new results on (a) bandwidth allocation algorithms, (b) the routing and protection of MPLS flows over an AAPN using the concept of OSPF areas, and (c) our evolving plans for building demonstration prototypes. Gregor v. Bochmann, University of Ottawa AAPN, 2007 2 Overview Overview of the AAPN project Frame-by-frame bandwidth allocation MPLS over AAPN A demonstration prototype Conclusions Gregor v. Bochmann, University of Ottawa AAPN, 2007 3 Different forms of “burst switching“ Question: Can one do packet switching in the optical domain (without oeo conversion)? At a switching speed of 1 μs, one could switch bursts of 10 μs length (typically containing many packets) Traditional packet switching involves packet buffering in the switching nodes. Should one introduce optical buffers in the form of delay lines? The term “burst switching“ originally meant “no buffering”: in case of conflict for an output port, one of the incoming bursts would be dropped. Note: Burst switching allows to share the large optical bandwidth among several virtual connections. Gregor v. Bochmann, University of Ottawa AAPN, 2007 4 AAPN An NSERC Research Network The Agile All-Photonic Network Project leader: David Plant, McGill University Theme 1: Network architectures Gregor v. Bochmann, University of Ottawa Theme 2: Device technologies for transmission and switching Gregor v. Bochmann, University of Ottawa AAPN, 2007 5 AAPN Professors (Theme 1 in red) McGill: Lawrence Chen, Mark Coats, Andrew Kirk, Lorne Mason, David Plant (Theme #2 Lead), and Richard Vickers U. of Ottawa: Xiaoyi Bao, Gregor Bochmann (Theme #1 Lead), Trevor Hall, and Oliver Yang U. of Toronto: Stewart Aitchison and Ted Sargent McMaster: Wei-Ping Huang Queens: John Cartledge (Theme #3 Lead) Note: Theme 2 deals with device technologies for transmission and switching For further information see: http://www.aapn.mcgill.ca/ Gregor v. Bochmann, University of Ottawa AAPN, 2007 6 The AAPN research network Our vision: Connectivity “at the end of the street” to a dynamically reconfigurable photonic network that supports high bandwidth telecommunication services. Technical approach: Simplified network architecture (overlaid stars) Specific version of burst switching Fixed burst size, coordinated switching at core node for all input ports (this requires precise synchronization between edge nodes and the core) See for instance http://beethoven.site.uottawa.ca/dsrg/PublicDocuments/Publications/Hall05a.pdf Burst switching with reservation per flow (virtual connection), either fixed or dynamically varying See for instance http://beethoven.site.uottawa.ca/dsrg/PublicDocuments/Publications/Agus05a.pdf Gregor v. Bochmann, University of Ottawa AAPN, 2007 7 Agile All-Photonic Network Edge node with slotted transmission (e.g. 10 Gb/s capacity per wavelength) Fast photonic core switch (one space switch per wavelength) Opto-electronic interface - Provisions submultiples of a wavelength - Large number of edge nodes Overlaid stars architecture Future of Networking, Lausanne, 2005 8 Starting Assumptions Avoid difficult technologies such as Wavelength conversion Optical memory Optical packet header recognition and replacement Current state of the art for data rates, channel spacing, and optical bandwidth (e.g. 10 Gbps) Simplified topology based on overlaid stars Large number of simple edge nodes (e.g. 1000) Fixed transmission slot length (e.g. 10 msec) No distinction between long-haul and metro networks This requires Fast optical space switching (<1 msec) Fast compensation of transmission impairments (<1 msec) Gregor v. Bochmann, University of Ottawa AAPN, 2007 9 AAPN Architecture Overlaid stars 2 Core Node 1 Edge Node A 3 6 B 4 8 Port sharing is required to allow a core node to support large numbers of edge nodes 7 5 A selector may therefore be used between edge and core nodes A wavelength stack of bufferless transparent photonic switches is placed at the core nodes a set of space switches, one switch for each wavelength Gregor v. Bochmann, University of Ottawa AAPN, 2007 10 Deployment aspects - Questions Long-haul or Metro ? connectivity “at the end of the street”; to a server farm AANP as a backbone network ? High capacity (many wavelengths) ? Multiple core nodes ? or low capacity (single or few wavelengths) For reliability For load sharing Transmission infrastructure ? Using dedicated fibers Using wavelength channels provided by ROADM network Gregor v. Bochmann, University of Ottawa AAPN, 2007 11 Overview Overview of the AAPN project Frame-by-frame bandwidth allocation (work by my PhD student Cheng Peng) MPLS over AAPN A demonstration prototype Conclusions Gregor v. Bochmann, University of Ottawa AAPN, 2007 12 Comparing Burst-Mode Schemes Long-haul AAPNs: long propagation delays for signalling Two modes of slot transmission: Collaboration with Anna Agusti-Torra (Barcelona) With reservation (long signalling delay) Without reservation, as proposed for “Burst Switching” (loss probability due to collisions) New method: Burst switching with retransmission (to avoid losses) Comparison with TDM (see next slide) Method to avoid long signaling delays: TDM Allocate unused time slots; these free slots can be used without signaling delays (they were allocated in advance) Gregor v. Bochmann, University of Ottawa AAPN, 2007 13 TDM vs. OBS OBS-R What kind of technologies should be employed in the AAPN, TDM or OBS? TDM Gregor v. Bochmann, University of Ottawa The delay of OBS w/ retransmission (OBS-R) degrades sharply when the load is beyond 0.6 but is negligible at lower load. The delay of TDM maintains better delay performance at the high load compared with OBS-R. TDM shows a better performance than OBS-R especially at the high load. AAPN, 2007 14 Birkhoff - von Neumann Approach The BvN decomposition approach calculates the timeslot schedules for a frame from the traffic demands between all node pairs. Two steps: Constructing a service matrix from a traffic matrix Decomposing the service matrix into switch permutations. (problem has O(N4.5) complexity) The main challenges of BvN Decomposition are: How to construct a service matrix that closely reflects the traffic demand for all source-destination pairs? How to find a heuristic decomposition algorithm with low complexity that allows a practical implementation? Gregor v. Bochmann, University of Ottawa AAPN, 2007 15 Service matrix construction similarity of final service matrix b) 0.95 0.9 projection method, = 0.5 projection method, = 0.25 max-min fairness 0.85 20 60 40 N Gregor v. Bochmann, University of Ottawa 80 New algorithm: Alternating Projections Method Similarity Comparison Compared with Max-min fairness method [7] The service matrices obtained with this Alternating Projection method have very high measures of similarity to the original traffic matrix, with an average similarity greater than 95% for N>=32. AAPN, 2007 16 Mean Queueing Delay (timeslot) Service matrix construction: queuing delay b) 8000 7000 Delay performance Alternating Projections Method Simple Rescaling Method Max-Min Fairness Method 6000 5000 Long-haul scenario, N=16, 1000km Tested under selfsimilar traffic Compared with 4000 3000 2000 1000 0 0.1 0.2 0.3 0.4 0.5 0.6 Offered Load Gregor v. Bochmann, University of Ottawa 0.7 0.8 0.9 Max-min fairness method [7] Simple rescaling method [8] Conclusion: performs better than the max-min fairness method or the simple rescaling method. AAPN, 2007 17 Mean Queueing Delay (timeslot) Heuristic decomposition algorithm b) 4 10 QBvN EXACT GLJD New algorithm: Quick BvN (QBvN) 3 10 Long-haul scenario, N=16, 1000km Tested under self-similar traffic Compared with 2 10 0.1 0.2 0.3 0.4 0.5 0.6 Offered Load Gregor v. Bochmann, University of Ottawa 0.7 0.8 0.9 Benchmark: Exact BvN Greedy Low Jitter Decomposition (GLJD) [11] Conclusions: excellent performance (close to optimum) Low complexity O(NF) AAPN, 2007 18 Overview Overview of the AAPN project Frame-by-frame bandwidth allocation MPLS over AAPN (work by my PhD student Peng He) A demonstration prototype Conclusions Gregor v. Bochmann, University of Ottawa AAPN, 2007 19 IP/MPLS routing over an AAPN ... Edge node Edge node router Edge node router Edge node Core node er rout Core node router Edge node Edge node ... Edge node AAPN Edge node router router One OSPF Area Gregor v. Bochmann, University of Ottawa AAPN, 2007 20 Solving the scalability problem Applying OSPF in a straightforward manner over an AAPN: AAPN with N edge nodes corresponds to N x N links in the routing table (1 000 000 links in case of 1000 edge nodes) Different approaches to introduce abstraction (we speak about “virtual routers” ) Vi No rtua de l #2 ... ... Edge node Edge node Edge node Edge node Edge node Edge node Edge node the core Edge node Edge node Edge node Edge node Edge node ... Edge node N Edge node Vi od rtu e al #1 ... the core Edge node Edge node Edge node Edge node Edge node the core Edge node ... ... Edge node Edge node Edge node Edge node ... ... Edgenode Edge node (a) AAPN exported as a full-meshed topology (c) AAPN exported as a edge-star topology l ua 4 rt # Vi de o N Edge node Edge node Edge node Virtu Nod al e #3 Edge node (d) Virtual node organization Edgenode Edge node (b) AAPN exported as a core-star topology Gregor v. Bochmann, University of Ottawa AAPN, 2007 21 Result: Optimal OSPF inter-area routes Area #2 OSPF can support multiple routing areas with only local routing Area #1 information v-ABR .. . Finding optimal inter-area research problem v-ABR routes is an open .. . This can be solved when the OSPF areas are interconnected by an AAPN: MPLS over AAPN Traffic Engineering Framework E4 R6 R2 E1 R8 E5 R3 R1 E2 E6 R7 R4 E3 R5 Area #1 Area #2 Area #0 R2 E1 E4 .. . R3 R1 R6 .. . E2 R8 E5 R4 E3 AAPN Architecture E6 R7 R5 Gregor v. Bochmann, University of Ottawa AAPN, 2007 22 Multi-layer resilience of MPLS flows over AAPN Using our traffic engineering framework as a starting point, we are working on multi-layer resilience of MPLS flows over AAPN, especially for inter-area (OSPF), intra-provider inter-AS and inter-domain network environments. End-to-end inter-area Resilience IP/MPLS Resilience IP/MPLS Resilience AAPN Optical Resilience Edge Resilience Edge Resilience Edge-to-edge Resilience Area #1 Area #2 Area #0 Vertical: Multi-layer R2 E1 .. . R3 .. . R8 E5 E2 R1 R6 E4 R4 R4 E3 AAPN Architecture E6 R7 R5 Horizontal: Multi-area Gregor v. Bochmann, University of Ottawa AAPN, 2007 23 Internet Exchange architecture with TE The principle of Virtual Routers can be applied to star-like networks in other situations: … Ethernet Switch (edge) Aggregation Ethernet Switch (core) IST SMLT BGP instead of OSPF Star-like Ethernet instead of AAPN … ASBR Examples: Edge node AAPN-based IX (AIX) Edge node ISP B (AS y) ... ... Core node Edge node Edge node ASBR Edge node Core node … existing Internet Exchange based on Ethernet Internet Exchange using an AAPN ASBR ISP A (AS x) Core node ASBR Edge node (E1) Optical Fiber ... Edge node ASBR ISP C (AS z) ... Route Server Content (e.g., IPTV) Server Edge node ASBR Gregor v. Bochmann, University of Ottawa AAPN, 2007 24 Overview Overview of the AAPN project Frame-by-frame bandwidth allocation MPLS over AAPN A demonstration prototype (in collaboration with the whole Theme-1 team) Conclusions Gregor v. Bochmann, University of Ottawa AAPN, 2007 25 Building an AAPN Control Platform Realizes algorithms and protocols for controlling an AAPN Easily adapting to the control interfaces of different core switches Easily integrating various control algorithms and protocols developed by different AAPN Theme-1 researchers Initial version may be running at slower speed (using standard PCs with optical Ethernet cards) Control information is exchanged through normal data blocks (no separate control channel) E1 E2 E3 E4 Co-located M1 E5 M2 Core Control interfaces Gregor v. Bochmann, University of Ottawa AAPN, 2007 26 Node architecture IP traffic layer Global SECM (edge node functions specific to bandwidth allocation algorithm in core node) GECM (generic signaling protocol) Switch control interface Gregor v. Bochmann, University of Ottawa AAPN layer Packet aggregation Burst buffering and transmission Burst reception and packetization Transmission & synchr. layer AAPN, 2007 27 Example timing diagram a frame period signalling Gregor v. Bochmann, University of Ottawa corresponding frame period at core node corresponding data transfer AAPN, 2007 28 - using essentially the same control software Slow prototype Control Platform runs on PCs, optical Ethernet transmission, MEM switch (slot time = 1 second) Completed in January (used to test control platform software) Intermediate prototype Most of Control Platform runs on PCs, optical transmission at 1 Gbps controlled by FPGAs, nanoseconds optical switch, slot time = 0.2 milliseconds Expected to be completed in July Improvements and extensions Add basic MPLS transmission in the IP Traffic Layer to allow experimentation with real applications MPLS routing and traffic engineering (TE) Experiment with bandwidth allocation algorithms proposed by AAPN researchers Other AAPN architectures (e.g. concentrators) Gregor v. Bochmann, University of Ottawa AAPN, 2007 29 Component-based edge node architecture PC with apps LAN IP / MPLS / Ethernet switching / routing + AAPN routing “basic” AAPN: Slot transmission Bandwidth alloc. PC with apps e.g. el. Giga-Ethernet PC with apps LAN “basic” AAPN: IP / MPLS / Ethernet switching / routing + AAPN routing Slot transmission Core node 1 Bandwidth alloc. PC with apps “basic” AAPN: PC with apps LAN PC with apps Slot transmission IP / MPLS / Ethernet switching / routing + AAPN routing Core node 2 Bandwidth alloc. AAPN edge node Gregor v. Bochmann, University of Ottawa AAPN, 2007 30 Conclusions The AAPN is a fascinating research project Premise: very fast switching and simple network architecture (overlaid stars) Theme-1 Outcomes: Theme-2 Outcomes: Proposal for slotted burst switching with bandwidth reservation (TDM, various allocation schemes) Internet-integration : AAPN as an OSPF area Various technologies for very fast switching, amplification, RRR, etc. Demonstration prototypes Gregor v. Bochmann, University of Ottawa AAPN, 2007 31