Advanced Network Architecture Research Advanced Network Architecture Research A Perspective on Photonic Multi-Protocol Label Switching Masayuki Murata Cybermedia Center, Osaka University Masayuki Murata Cybermedia Center, Osaka University

Advanced Network Architecture Research Advanced Network Architecture Research Contents 1.MP S (MPLS based on WDM Lightpaths) Implementation Issues and Challenging Problems 2.OC-MPLS (MPLS based on Optical Code) Optical Implementations and Challenging Issues 3.Perspectives on MP S and OC-MPLS Advantages and Disadvantages 1.MP S (MPLS based on WDM Lightpaths) Implementation Issues and Challenging Problems 2.OC-MPLS (MPLS based on Optical Code) Optical Implementations and Challenging Issues 3.Perspectives on MP S and OC-MPLS Advantages and Disadvantages

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata3 Past Researches on WDM Networks q Routing and Wavelength Assignment (RWA) Problem m Static assignment 4 Optimization problem for given traffic demand m Dynamic assignment 4 Natural extension of call routing 4 Call blocking is primary concern 4 No wavelength conversion makes the problem difficult q Optical Packet Switches for ATM m Fixed packets and synchronous transmission IP Router Ingress LSR N 2 N 4 N 1 N 3 Core LSR -MPLS 1 1 N 5

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata4 Mapping from Generic MPLS to Lambda MPLS (or GMPLS) Ingress LSR; Maps from IP address to lambda Ingress LSR; Maps from IP address to lambda X X X X X X LSR (Label Switching Router); Optical crossconnect directly connecting input wavelength to output wavelength LSR (Label Switching Router); Optical crossconnect directly connecting input wavelength to output wavelength LSP (Label-Switched Path); Wavelength path (Lightpath) LSP (Label-Switched Path); Wavelength path (Lightpath) LDP (Label Distribution Protocol); Dimensioning by wavelength and routing assignment algorithm LDP (Label Distribution Protocol); Dimensioning by wavelength and routing assignment algorithm Wavelength DemuxWavelength Mux Optical Crossconnect λ 1 λ 1 λ 1 λ 1 λ 2 λ 2 λ 2 λ 2 λ 2 λ 1 λ 1 Optical Switch

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata5 q Four Kinds of Architecture 1.WDM link network 4 Connects adjacent routers by WDM (multiple wavelengths increase the bandwidth) 2.WDM path network 4 Cut-through techniques for IP packets on established path provided by the underlying networks Photonic Internet Architecture Router Optical Crossconnect Router X X X X X X

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata6 3.WDM Path Network 4 Lambda switching by MPLS technology (MP S or GMPLS) 4.WDM Packet- switched Network 4 E.g., burst switching by routing and wavelength assignment (RWA) on demand basis Photonic Internet Architecture (Cont’d) X X X X X X Optical Cross-Connect Router X X X X X X burst

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata7 Logical Topology by Wavelength Routing q Physical Topology o Logical Topology IP Router Ingress LSR N 2 N 4 N 1 N 3 Core LSR -MPLS 1 1 N 5 IP Router Ingress LSR N 2 N 4 N 1 N 3 Core LSR -MPLS 1 1 N 5 2 Wavelength Demux Wavelength Mux Optical Cross-Connect N 2 N 3 N 4 N 2 N 3 N 4 Optical Switch

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata8 Logical View Provided to IP q Redundant Network with Large Degrees F Smaller number of hop-counts between end-nodes F Decrease load for packet forwarding at the router F Relief bottleneck at the router IP Router

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata9 MPLS-based WDM Network q Needs many wavelengths to maintain all-to-all connectivity q To reduce the # of required wavelengths, paths should be cut within the network IP Router Ingress LSR N 2 N 4 N 1 N 3 Core LSR -MPLS 1 1 N 5 IP Router Ingress LSR N 2 N 4 N 1 N 3 Core LSR -MPLS 1 1 N 5

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata10 Lightpath Splitting by Wavelength Router q Physical Topology o Logical Topology IP Router Ingress LSR N 2 N 4 N 1 N 3 Core LSR -MPLS 1 1 N 5 Wavelength DemuxWavelength Mux Wavelength Router Electronic Router Electronic Router N 2 N 3 N 4 N 2 N 3 N 4 Optical Switch IP Router Ingress LSR N 2 N 4 N 1 N 3 Core LSR - MPLS 1 1 N 5

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata11 Challenging Problems of MP S q Logical Topology Design Issues m Past researches assume the traffic matrix is given m Objective is maximization of wavelength utilization or minimization of the required # of wavelengths m Optimization problem is then solved by LP or heuristics q Bottleneck at Ingress Nodes m Bottleneck is shifted to the Ingress Nodes requiring electronic processing q Survivability m IP and WDM Functional Partitioning or Integration

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata12 Incremental Capacity Dimensioning Approach q Initial Phase m Design Logical topology with given traffic demand q Incremental Phase m primary lightpath is incrementally setup m reconfigure backup lightpaths q Readjustment Phase m All of the lightpath (including primary lightpath) is reconfigured Readjustment Phase Incremental Phase Initial Phase Reconfigure backup lightpaths Reconfigure both primary and backup

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata13 Traffic Load Distribution by WDM Ring q Distribute the traffic load by WDM ring at the Ingress node 1 Ingress LSR -MPLS WDM Ring

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata14 Effects of Introducing WDM Ring Packet Processing Rate Required at RouterRequired Number of Wavelengths 10+E2 10+E3 10+E4 10+E Required Processing Capability (Mpps) The Number of Local Nodes L N Logical Degree = Required # of Wavelengths The Number of Local Nodes L N 8 Logical Degree =

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata15 Do We Need More “Intelligent” WDM Network? q WDM network itself has network control capabilities m Routing function 4 IP also has it! m Congestion control function 4 TCP also has it! 4 TCP over ATM (ABR service class) is difficult to work well Parameter tuning of control parameters in ABR is not easy m Connection establishment 4 IP is connectionless 4 Multimedia application does not require 10Gbps channel m Multi-layered Functionalities? q Important is reliability

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata16 Functional Partitioning between IP and WDM? q Reliability functionalities offered by two layers m IP Layer: Routing m WDM Layer: Path Protection and Restoration q WDM should provide its high-reliability mechanism to IP m Protection mechanism 4 link protection 4 dedicated-path protection 4 shared-path protection m Network dimensioning is important to properly acquire the required capacity of IP paths (traffic glooming) 4 Reconfiguration mechanism of logical topology by wavelength routing

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata17 WDM Protection q Immediately switch to backup path on failure of nodes/links m In the order of 10ms q 1:1 Protection vs. Many:1 Protection q Protection technique suitable to IP over WDM network? m IP has its own protection mechanism (i.e., routing) while it is slow m We want an effective usage of wavelengths m Many:1 protection is reasonable 1:1 Protection Primary Path Backup Path Many:1 Protection Primary Path

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata18 Formulation of Reliability Design Problem for Many-to-1 Path Protection q Objective m Minimize the utilized wavelengths in total q Given Conditions m The number of wavelengths on the fiber m Physical topology and logical topology m Primary routes F Formulated as MILP (Mixed Integer Linear Problem) q Application to 5-node network N0 N3 N2 N1 N4 Wavelength Sharing

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata19 Readjustment Phase Incremental Phase Initial Phase Example of our approach

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata20 Initial Phase q Design Initial Topology for given/inspected traffic demands. q Static Design method can be applied m Primary lightpaths: MLDA algorithm 4 R.Ramaswami, K. N. Sivarajan, “Design of logical topologies ….” m Backup lightpaths: Min-hop-first algorithm 4 S.Arakawa, M.Murata, H.Miyahara, “Functional Partitioning … ” q Various objective function is considered in existing design methods q But, the number of wavelengths should be minimized m remaining wavelengths can be flexibly utilized for the increasing traffic in the incremental phase.

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata21 Incremental Phase q Set up lightpaths according to the traffic change q Traffic change is detected by traffic measurement m lightpath utilization measurement at router (passive measurement) m end-user’s QoS measurement at user’s PC (active measurement) q No primary lightpath is changed m so that the active traffic flows are not affected by lightpath rearrangement q Only adding primary lightpath is allowed q Backup lightpath is preemptive m Backup lightpaths do not carry the traffic unless the failure occurs m For an effective use of wavelengths, the backup lightpaths are preemptive and to be reconfigured

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata22 Lightpath Setup Procedure in Incremental Phase q Traffic measurement is performed at each node q Node requests a special node to set up both primary and backup lightpaths q The special node tries to m Set up primary lightpaths m Reconfigure backup lightpaths q Only the above two trial is found to success, the requests is accepted and actually reconfigured 1. Traffic measurement 2. Lightpath setup request Lightpath Management Node 3. RWA for primary lightpath 4. Reconfigure backup lightpaths 5. Modify the lightpaths Existing primary/backup lightpath New primary/backup lightpaths 6. acceptance

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata23 Lightpath Setup Procedure in Incremental Phase (Cont’d) q At the special node, following configuration must be performed m Routing and wavelength assignment for primary lightpath m Reconfigure backup lightpaths q Primary lightpaths are set up as if there are no backup lightpath m Backup lightpath is preemptive q Reconfiguration of backup lightpaths m Formulated as optimization formulation m Minimize the # of wavelengths used for backup lightpaths

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata24 Readjustment Phase q Resolve an inefficient usage of wavelengths, which is caused by the dynamic and incremental wavelength assignments q All the lightpaths (including primary lightpaths) are reconfigured m The static design method can also be applied q Primary lightpaths are already serving to transport the active traffic m An influence of a reconfiguration operation should be minimized even if the resulting logical topology would be a semi–optimal solution m step by step configuration: branch–exchange method

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata25 Routing Cross-Connect, Switch and Router q Photonic switch within MPLS requires m packet forwarding based on “label” m queue management based on “label” m packet switching and buffering payload header Cross-Connect Photonic Packet Switch supported by GMPLS Photonic IP Router Buffering Queue Management Queue Management Forwarding Switching

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata26 Label Swapping in MPLS Ingress LSR In LabelOut Label 104 Label Swapping In LabelOut Label Label Swapping In LabelOut Label Label Swapping Core LSR Egress LSR

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata27 Optical Code based MPLS q Photonic label based on optical codes Output fiber N -DEMUX Input fiber 1 Input fiber N Output fiber 1 1, 2,..., K 1 K MUX OC- MPLSR#1 1 OC- MPLSR#1 1 OC- MPLSR#N K OC- MPLSR#N K Photonic label processor Photonic label processor Optical switch Optical switch Photonic label swapper Photonic label swapper Input packets Output packets t 1 bit time 0  OC-based photonic label Optical buffer Optical buffer OC-based Switching Node OC –based Switch

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata28 Photonic Label Processing q Optical code by BPSK q Photonic label processing in optical domain m photonic label is tapped from packet header m optically dupilcated by optical amplification m power-splitted as many copies as the count of label entries in the table m optical correlations between the copies and the label entries is performed in parallel Input ReplicasAddress entriesOutput Duplication Correlation x t t t t t t t #1 # 10 4 x10 4 t t t

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata29 Temporal Waveform of 8-chip Equi-amplitude BPSK Code Sequence q After the propagation in a long dispersion shifted fiber, its auto-correlation before and after time gating from the left. The calculations are made under the following conditions; wavelength dispersion D = ps/nm/km and the loss = 0.2dB/km. Fiber nonlinearity is ignored. Time (ps) Correlation (a.u.) Time (ps) Power (a.u.) Time (ps) Power (a.u.) 50km 100km 150km Back-to-back 50km 100km 150km Back-to-back 50km 100km 150km Back-to-back

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata30 Implementations of Optical Buffers by Delay Lines Input packet Output packet DL1DL2 2x2 switch (a) Multi-stage switched delay line buffer EDFA:Erbium doped fiber amplifier PC: Polarization controller PC EDFA (b) Re-circulating loop buffer

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata31 Photonic Packet Switch for Asynchronously Arriving Variable Packets q Buffer Scheduling m Delayed Line Buffer q Variable-Length Packets m Counter for Buffer State; b ij for output line j on wavelength i m For each arrival of packet with length x For each delay unit D q For asynchronous arriving m Introduce packet sequencer

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata32 Structure of OC-based Photonic Packet Switch Without Wavelength Conversion

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata33 Structure of OC-based Photonic Packet Switch With Wavelength Conversion Optical Switching UnitOptical Scheduling UnitOptical Buffering Unit Scheduler S 1 O1O1 I1I1 -DEMUX 1 - W -MUX 1 W 1 - W 1 W SC+Gate 1 OC Encoder/ Decoder OC Encoder/ Decoder b 1W W 1 W SC+Gate 1 OC Encoder/ Decoder OC Encoder/ Decoder 00 11 22 00 11 22 b 11 1 Header Photonic label processor Photonic label processor Optical SW1 Photonic label processor Photonic label processor Optical SW Photonic label processor Photonic label processor Optical SW1 Photonic label processor Photonic label processor Optical SW 1 Header W W 1 W Scheduler S 2 O2O2 I2I2 -DEMUX 1 - W -MUX 1 W 1 - W 1 W SC+Gate 1 OC Encoder/ Decoder OC Encoder/ Decoder b 2W W 1 W SC+Gate 1 OC Encoder/ Decoder OC Encoder/ Decoder 00 11 22 00 11 22 b 21 1 Photonic label processor Photonic label processor Optical SW1 Photonic label processor Photonic label processor Optical SW Header Photonic label processor Photonic label processor Optical SW1 Photonic label processor Photonic label processor Optical SW 1 Header W W 1 W Time Synchronizer

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata34 Performance of Proposed Switch 1E-18 1E-16 1E-14 1E-12 1E-10 1E-08 1E-06 1E-04 1E Packet Loss Probability The Number of Wavelengths W  = 0.85  = 0.8  = 0.75  = 0.65  = 0.7

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata35 Problems of MP S q The incremental capacity dimensioning is infeasible in the current logical topology design approach m Network performance is heavily dependent on the logical topology design approach q Unit of Path Granularity is Wavelength Capacity m too large to accommodate the end-to-end traffic m The capacity increase per each wavelength does not alleviate the problem m The increase in the number of wavelengths may help it. However, it requires the large-scaled of, e.g., 1,000x1,000 optical cross-connect q Flow aggregation at the Core LSR cannot be expected m The label exchange within the network poses the wavelength change at an optical node

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata36 Advantages of OC-MPLS q The granularity is “packet” m Allows a flexible network structure m Simplified packet switching can offer large capacity in the optical domain m An ATM-based MPLS protocol suite can be applied m Traffic engineering developed for MPLS is also utilized. q OC-MPLS is capable of merging of packets by introducing optical buffering m Attains an ultimate bandwidth efficiency m MP S is unable to realize it due to the coarse granularity. q The length of OC photonic label could be flexible m The longer label could be used as the network layer header of the packet m Can be used both to assigned multiple flows from IP prefix to application-level flow m Possible to offer QoS-enabled services m Optical codes are not only applicable to the exact match algorithm in the OC-MPLS but also applicable to the longest prefix match, and hence OC- based destination-based IP routing might be realizable.

Osaka University Advanced Network Architecture Research Advanced Network Architecture Research M. Murata37 Remaining Problems of Establishing OC-MPLS q The switch fabric, constructed with photonic space switch and photonic buffer, has to be optimized to achieve the desired performance q Statistical multiplexing would work well by very huge bandwidth provided by OC techniques even if the packet buffer capacity is not large. However, a further research on the traffic engineering approach of MPLS is necessary under the conditions that the bandwidth is very large, but the packet buffer size is small.