Optical Label Swapping Research Articles

A survey on all optical label swapping techniques: Comparison and trends

The rapid growth of packet based Internet traffic and big data, associated with interconnected Data Centers (DC) and High Performance Computing (HPC) systems have imposed the need for ultrahigh link capacities and ultrahigh packet switching speeds, at network nodes. In order to overcome these ultrahigh demands, and particularly packet routing and forwarding, All Optical Label Swapping (AOLS) has been considered for many years as an established solution. This survey paper gives an updated and thorough investigation on AOLS technology and trends, based on a vast reference amount of research milestones throughout all this long time era. All types of labeling techniques are presented and compared, and their pros and cons are summarized all together. Moreover, important issues and directions for research are discussed, giving researchers guidelines and motivation for extended investigation.

Linear random code-based label encoding scheme for label swapping free optical packet switching networks

Optical Label Switching (OLS) has been considered to be a promising approach to realize optical packet switching (OPS) networks. In an OLS router, the header processing module retrieves the routing information carried in the optical header and then replaces the old header with a new one through optical label swapping. The cost-effectiveness and the speed of performing label swapping are two major concerns. Due to lack of optical random access memory, optical label swapping has become a big challenging issue in implementing OLS switches. To overcome these difficulties, in this paper, we propose two Linear Random Code (LRC)-based label encoding schemes to achieve label swapping free OPS networks. Using the proposed schemes, a small sized label is needed. Only simple modulo-2 multiplication and modulo-2 addition operations are required to decode an optical label and there is no optical label swapping during packets traverse along the entire routing path. In our system, each source–destination pair is assigned multiple paths so the network is with traffic engineering and fault tolerance capabilities. We have carried out extensive simulations to evaluate the performance of the proposed scheme. Compared with the well-known KIS encoding scheme, the proposed LRC-based scheme can reduce the label size significantly. An 8-byte LRC label is long enough to support all node pair with five paths in a 300-node network.

Proses Pengiriman Paket IP Menggunakan All Optical Label Swapping (AOLS)

Transmission IP packet into WDM network will experience of encapsulation process at Data Link Layer with adding overhead to packet. IP packet through Gigabit Ethernet have more less overhead than ATM. The usage of All Optical Label Swapping (AOLS) technology for transmitting IP packet into WDM network with using label swapping will add optical label to packet. At AOLS, process routing decision is to be done with only processing the optic label. During that process data payload constantly within optic domain. Key word : ATM, Gigabit Ethernet, AOLS, optic label.

Optical Code-Labeled Router Based on OCDM

An optical code-labeled router that performs packet forwarding through optical code label swapping (OCLS) based on code division multiplexing technology is proposed. It can enhance the processing speed of packets that can adapt to the growth of data and the aggregation of data service. The throughput of the router increases obviously since the optical code division multiplexing (OCDM) paths on the same wavelength can be processed in parallel. Moreover, it is attractive for its traffic control, bandwidth efficiency, protocol transparency, channel granularity, and so on.

All-Optical Label Swapping Using Bistable Semiconductor Ring Laser in an Optical Switching Node

This paper demonstrates an optical node that simultaneously carries out multicast optical switching and all-optical label swapping. While the optical payload is being forwarded by a fast optical switch matrix, the optical label is processed by a semiconductor ring laser (SRL) bistable. Old address bits in the label are erased by optically blocking the switching of the ring laser and new address bits are inserted by modulating the output from SRL directly. This label swapping scheme is the first demonstration of bit-level data processing using the all-optical logic capabilities of a semiconductor ring laser.

All-optical label swapping of in-band addresses and 160 Gbit/s data packets

A 1×4 all-optical packet switch is presented, based on an optical label swapping technique that utilises a scalable label processor and a label rewriter with ‘on the fly’ operation. Experimental results show error-free packet switching with a data payload at 160 Gbit/s. The label erasing and new label insertion operation introduces 0.5 dB of power penalty. These results indicate a potential utilisation of the presented technique in a multi-hop packet switched network.

Improved optical coding method for orthogonal ASK/DPSK modulation format

Orthogonal ASK/DPSK labeling, which encodes label information on optical carriers in a modulation format, is regarded as a competing scheme to subcarrier multiplexed optical labeling. However, the inherent cross-talk limits the extinction ratio (ER) of the payload and label sensitivity. In this paper, two optical coding methods-Manchester coding and 8B10B coding-which can remarkably improve the system quality to obtain acceptable ER are discussed. A novel optical packet encoding method-mark-insertion coding-is demonstrated to significantly reduce cross-talk between the amplitude shift keying (ASK) payload and the differential phase shift keying (DPSK) label through spectrum shaping. The performance of mark-insertion coding depends on the number of inserted ‘marks’. Finally, the transmission over a 40 km single mode fiber (SMF) is compared with optical label swapping for a 40 Gbit/s ASK payload and 2.5 Gbit/s DPSK label under these coding schemes. The experimental result is consistent with the theoretical analysis.

Investigation on the Signal Misalignment in Subcarrier Multiplexed Optical Label Swapping Routers: An Experimental Verification

This paper presents a theoretical and experimental evaluation of the subcarrier-multiplexing label and payload alignment in an optical label-swapping router; optical packets, which are composed of label and payload, are transmitted from the edge router to the core router, where the labels are processed, and the new labels are reassembled to the payload in a synchronized operation. True delays of the signals in the core router are precisely evaluated, and synchronization aspects are studied in detail. For the first time, to our knowledge, the experimental verification allows the evaluation of the delay-tolerance range in the process of coding the baseband label onto the optical packet without affecting the normal operation of the router. Key issues found in the core-router implementation are thoroughly described throughout this paper.

All-Optical Label Swapping, Clock Recovery, and 3R Regeneration in 101-Hop Cascaded Optical-Label Switching Router Networks

This paper experimentally demonstrates the cascaded operation of an optical-label switching router for up to 101 hops, with optical label swapping, optical clock recovery, and 3R regeneration (re-amplification, reshaping, and retiming) at each hop. The optical label swapping utilizes all-optical payload/label separation and label rewriting with subcarrier label. An interferometer wavelength converter enables the reshaping function, while the synchronous modulation driven by the optically recovered packet clock performs the retiming function. The optical label swapping and 3R regeneration enable the packets to traverse a large number of hops while maintaining the signal quality to support the scalability of the optical-label switching network

On intranode impairments and engineering rules for an optical label switching router supporting an FSK/IM labeling scheme

This paper presents a study on intranode impairments and engineering rules for a label switching router supporting intensity modulated (IM) optical payload data signals labeled by using frequency-shift key (FSK) modulation. Engineering rules and design guidelines are presented regarding the choice of system parameters such as IM extinction ratio, FSK frequency deviation, alignment of optical filtering stages, label swapping, and node cascadability. The presented rules are derived from insights obtained from computer simulations and experimental validation for a 10-Gb/s IM payload signal

Cascadability study for optical label swapping using synchronous phase modulation

We experimentally investigate the cascadability of optical label swapping using a synchronous phase modulation technique without wavelength conversion in a recirculating loop to emulate multihop networks. We find that the power penalties for both label and payload are below 1 dB at 10-7 bit-error rate after five hops. We also show that a system penalty can be maintained below 1 dB for an accumulated timing mismatch of 20% of bit period using synchronous phase modulation-based optical label swapping. The results show the potential to save up to 80% of wavelength converters in optical packet switched networks applications

All-optical label processing techniques for pure DPSK optical packets

We present two all-optical label processing schemes for pure differential phase shift keying packets. The two techniques are based on the already used optical correlators and on a novel time-to-wavelength conversion of the label information. They require that the label information is encoded by using pulse position modulation, which makes the label processor simpler and can allow very fast processing speed. We investigate and compare the efficiency in terms of packet overhead of pulse position modulation coded labels with ordinary binary coding and show that pulse position modulation is still attractive for medium-size network and for system implementing optical label swapping. We then experimentally demonstrate that the two techniques can distinguish several labels at distinct outputs. Both operate at low optical power, asynchronously, and could allow for photonic integration. Scalability and processing speeds of the two systems are discussed. We also show that the two label processors can be used to implement an optical label swapping system. Experimental results show that the two labels are distinguished at two distinct ports and erased from the incoming packet, so that a new label can be inserted. Scalability and processing speed are discussed as well

Scalability of 10 Gbit/s SCM optical label swapping networks featuring 2R multistage intra-node regeneration

The scalability of an all-optical packet-switched network based on subcarrier multiplexed optical label swapping routers with two wavelength conversion stages and 2R payload regeneration are experimentally demonstrated. Measurements up to 16 hops in the network with 10 Gbit/s payload show 1 dB penalty with 10−12 bit error rate.

Enabling Technologies for Next-Generation Optical Packet-Switching Networks

The optical packet-switching network is considered to be one of the most promising solutions for end-to-end delivery of high-bitrate data, video, and voice signals across optical networks of the future. Optical label switching (OLS) technology incurs simpler extraction and processing of the labels so that the optical packets can be routed with low latency to the destinations. We have developed several key enabling technologies for integrated optical networks, including optical label generation, label swapping, optical buffering, clock recovery, and wavelength conversion. We have designed and experimentally demonstrated these enabling techniques that can provide efficient broadband services in future optical networks.

Improve the performance of orthogonal ASK/DPSK optical label switching by DC-balanced line encoding

Orthogonal amplitude shift keying/differential phase-shift keying (ASK/DPSK) labeling is a promising approach to ultrahigh packet-rate routing and forwarding in the optical layer. However, the limitation on the payload extinction ratio (ER) is a detrimental effect for network scalability and transparency. This paper presents theoretical and experimental studies of ASK/DPSK labeling. It proposes that dc-balanced 8B10B coding can greatly improve ER tolerance, which in turn leads to better system performance. By using the 8B10B coding method, the paper demonstrates transmission and optical label swapping for a 40 Gb/s ASK payload and a 2.5 Gb/s DPSK label with an overall power penalty of 3.3 dB for the payload and 0.3 dB for the label. The experimental results also show that the ER is allowed to be as high as 12 dB

Dimensioning of 10 Gbit/s all-optical packet switched networks based on optical label swapping routers with multistage 2R regeneration

This paper describes both the experimental and theoretical investigations on the cascadability of all-optical routers in optical label swapping networks incorporating a multistage wavelength conversion with 2R regeneration. A full description of a novel experimental setup allows the packet by packet measurement up to 16 hops with 10 Gb/s payload showing 1 dB penalty with 10(-12) bit error rate. Similarly, the simulations on the system allow a prediction on the cascadability of the router up to 64 hops.

An optically clocked transistor array with dual serial-to-parallel and parallel-to-serial conversion capability for optical label swapping

We propose an optically clocked transistor array optoelectronic integrated circuit (OEIC) for both serial-to-parallel and parallel-to-serial conversion (demux/mux), enabling an interface between high-speed asynchronous burst optical labels and CMOS circuitry for optical label swapping. Dual functionality of the OEIC reduces size, power, and cost of the optical label swapper. The capability for greater than 20-Gb/s conversion operation is demonstrated.

Fiber-Bragg-grating-based device for payload and label separation in highly packed subcarrier-multiplexed optical label swapping

We report a fiber-Bragg-grating-based device for an efficient separation of the payload and label in highly packed subcarrier-multiplexed optical label swapping networks. The separation is performed in the optical domain by a tandem fiber Bragg grating device consisting of two specially designed fiber Bragg gratings separated by an isolator. We experimentally demonstrate that the proposed configuration provides an excellent separation of the payload and label in the optical domain.

Optical label swapping using payload envelope detection circuits

Optical label swapping of 10-Gb/s nonreturn-to-zero (NRZ) labels attached to 40-Gb/s return-to-zero payloads is demonstrated using payload envelope detection (PED) circuits based on 40-Gb/s clock recovery with nanosecond locking time. The circuits generate a digital envelope signal representing the payload location without having to process the 40-Gb/s data. The low-frequency PED signal, which is generated from the recovered 40-GHz packet clock by a radio-frequency mixer, can be utilized to erase/rewrite the label through traveling-wave electroabsorption modulators. This approach does not require active timing control to erase the label. Nearly penalty-free rewriting of a new 10-Gb/s NRZ label was demonstrated.

Transmission and optical label swapping for 4/spl times/40 gb/s WDM signals deploying orthogonal ASK/DPSK labeling

In this letter, we report a novel amplitude shift keying/differential phase-shift keying (ASK/DPSK) optical packet encoding method that can significantly reduce the crosstalk between the ASK payload and the DPSK label through spectrum shaping. We demonstrate wavelength-division-multiplexing (WDM) transmission for 4/spl times/40 Gb/s labeled return-to-zero signals, including label swapping by Kerr switching of one of the channels, with an overall penalty of 3.3 dB for the payload and 0.3 dB for the label, clearly validating this orthogonal modulation scheme as a potential solution for future ultrahigh-speed Internet protocol-over-WDM networks.