GMPLS and IP+MPLS interworking technologies - routing and signaling

Generalized multi-protocol label switching (GMPLS), which supports all types of switching, can provide next-generation mobile broadband IP networks with quality of service (QoS) and traffic engineering (TE). Future core network of wireless mobile system will be the GMPLS-based wired IP network; GMPLS must provide an efficient scheme to support micro-mobility in wireless environment. The purpose of this paper is to propose a scheme of integrating GMPLS with micro-mobility for the next-generation mobile broadband IP networks. The proposed scheme can re-establish a label switched path (LSP) rapidly when a mobile node (MN) enters a new subnet. Therefore, low latency performance can be achieved. The resource utilization in GMPLS networks can also be improved.

The ITU-T defined next generation network (NGN) architecture designates the resource admission control function to perform the application-driven Quality of Service (QoS) control across access and core networks. The Generalized Multiprotocol Label Switching (GMPLS) was introduced by the Internet Engineering Task Force (IETF) to cope with new traffic engineering challenges in fast optical networks and provide them with reliable end-to-end QoS mechanisms. However, an actual Connection Admission Control (CAC) implementation inside the resource reservation protocol - traffic engineering extension (RSVP-TE) in GMPLS networks does not provide the ability of effective decision making, since the applied threshold CAC lacks of the capability to consider QoS policies on GMPLS network nodes. This prevents an effective end-to-end QoS control in a fully dynamic, application driven Label Switched Path (LSP) setup scenario. This work presents a specific implementation of fuzzy-CAC operating over an RSVP-TE agent in GMPLS network domain. This fuzzy-CAC implementation is applied to a testbed where a client application requests a real-time data transfer through a GMPLS network, which results in dynamic LSP setup and exclusion. The admission control is performed upon service request based on QoS class requirements and network resource availability. The differentiated traffic treatment on per-flow basis is realized through employment of IF-THEN rule based expert knowledge. Effective traffic differentiation is achieved in a multi-service network scenario and thus it validates fuzzy-CAC as candidate for RSVP-TE protocol enhancement for application driven QoS provisioning in GMPLS networks.

In this paper, we studied survivability in general multi‐protocol label switching (GMPLS) multi‐layered optical networks and proposed a novel mixed shared protection algorithm (MSPA) based on the integrated layered graph (ILG) to tolerate single‐fibre link failure. The ILG is composed of one virtual topology layer (VTL), corresponding to IP/MPLS layer; multiple wavelength‐plane layers (WPLs), corresponding to the wavelength‐division multiplexing (WDM) optical layer; and some virtual links that connect the VTL to each WPL in order to solve the problem on routing, wavelength assignment and low‐speed traffic grooming. For every connection request, the MSPA first computes a single‐hop or multi‐hop label switching path (LSP) pair, involving a working LSP and a physical link‐disjoint backup LSP in the VTL. If the LSP pair is not found in the VTL, the MSPA computes the new LSP pair in the WPL. Conversely, if the new LSP pair is not detected in the WPL, the MSPA computes the hybrid multi‐hop LSP pair in the ILG. In the MSPA, if the two working LSPs are in physical link‐disjoint, their corresponding backup LSPs can share the backup bandwidth. In addition, the working LSPs and the backup LSPs can also share the same mixed of wavelength, in which the different bandwidths can be assigned to different working and backup LSPs. Simulation results show that, compared to previous algorithm, the MSPA can obtain a better bandwidth utilisation ratio (BUR) with a lower blocking probability. Copyright © 2010 John Wiley & Sons, Ltd.

Chapter 3 - From MPLS to GMPLS

Generalized multi-protocol label switching (GMPLS) has emerged as a very promising protocol technology for the next generation optical networks. GMPLS successfully combines the best features of IP and ATM in terms of quality of service (QoS), privacy, flexibility and scalability. GMPLS introduces enhancements to the existing IP routing and signaling protocols by supporting not only networks that perform packet switching (IP), but also networks that perform switching in the time (TDM), wavelength (DWDM), and space domain (circuit switching). This paper discusses the design and implementation of a modeling tool for analysis of GMPLS optical switching routers (GOSR). A model of the GOSR has been built using OPNETTM modeling and simulation platform, in lieu of a prototype. The virtual model contains all the necessary GMPLS functions of an optical backbone router. The description on the design features and the key implementation elements of the internal mechanism of GOSR forms the introduction of this paper. The virtual model of the GOSR has the capability of giving a more integrated and realistic simulation on wavelength routing, wavelength assignment, wavelength switching, dynamic label switching path (LSP) setup and tear down, and blocking mechanism of GMPLS light paths. The OPNET process modeling methodology was used to develop the virtual GOSR models. The simulation results obtained include the blocking rate, OSPF-TE bandwidth analysis, and CPU utilization. The modeling environment developed in this project provides a simulation platform for further development and future enhancement of GMPLS protocols, routing protocols, and optical switching router implementations.

A multicode variable-weight (MCVW) technique is proposed for generalized multiprotocol label switching (GMPLS) optical networks in order to support multirate and integrated multimedia services. Under this technique, the number of simultaneously assigned codewords to each user is a function of the data rate of the service class, while quality-of-service differentiation is achieved using variable-weight codewords for each service class. The traffic behavior of the network is modeled using a multiservice loss model, and the probability density functions of the number of busy codes in the fiber link are obtained by the Kaufman–Roberts algorithm. In order to analyze the performance of the proposed multiservice multicode GMPLS optical network, several measures are derived and investigated, specifically, the bit-error rate, probability of degradation, blocking probability, and steady-state throughput. These performance measures are obtained for two different receiver structures, namely, correlation receivers with and without hard limiters. The performance of our optical GMPLS network, based on the multicode switching path, is compared with that of traditional optical GMPLS networks, based on the label switching path. The results show the superiority of the proposed technique when compared to traditional ones.

The multiprotocol label switching (MPLS) standard defined by the Internet Engineering Task Force do not consider bidirectionality. In effect, to have bidirectionality two different label switched paths (LSP) have to be established. On the contrary, the generalized multiprotocol label switching (GMPLS) paradigm, by introducing a new object to the signalling protocol, supports bidirectionality. However it does not rely to unidirectional optical connections over unidirectional optical rings. This paper describes two solutions implemented in the ASON/GMPLS CARISMA network, and some experimental results regarding the establishment of soft-permanent connections are presented and discussed.

A Path Computation Element (PCE) based architecture has been specified for the computation of Traffic Engineering (TE) Label Switched Paths (LSPs) in Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) networks in the context of single or multiple domains (where a domain refers to a collection of network elements within a common sphere of address management or computational responsibility such as IGP areas and Autonomous Systems). Path Computation Clients (PCCs) send computation requests to PCEs, and these may forward the requests to and cooperate with other PCEs forming a path computation chain. In PCE-based environments, it is thus critical to monitor the state of the computation chain for troubleshooting and performance monitoring purposes: liveness of each element (PCE) involved in the PCE chain, detection of potential resource contention states and statistics in term of computation times are examples of such metrics of interest. This document specifies procedures and extensions to the Path Computation Element Protocol (PCEP) in order to gather such information.

The ability to compute shortest constrained Traffic Engineering (TE) Label Switched Paths (LSPs) in Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) networks across multiple domains (where a domain is referred to as a collection of network elements within a common sphere of address management or path computational responsibility such as IGP areas and Autonomous Systems) has been identified as a key requirement . This document specifies a procedure relying on the use of multiple Path Computation Elements (PCEs) in order to compute such inter-domain shortest constrained paths along a determined sequence of domains, using a backward recursive path computation technique while preserving confidentiality across domains, which is sometimes required when domains are managed by different Service Providers.

QoS routing in GMPLS-capable integrated IP/WDM networks with router cost constraints

Due to the explosive growth of real-time and multimedia-oriented applications and services on the Internet, network survivability becomes much more important than before. Future mobile broadband IP networks will be generalized multiprotocol label switching (GMPLS) based. Many protection and restoration (P&R) techniques have been developed to improve survivability in GMPLS-based IP networks. We propose an efficient two-level P&R scheme for GMPLS-based IP networks. In the scheme, LSP (label switched path) P&R is the first level and LSP segment P&R is the second level. An LSP protection path selection (LPPS) algorithm has been designed for the proposed scheme. The protection path establishment acceptance rate can be improved in the scheme. The proposed scheme achieves better quality of service (QoS) and reliability guarantees. In addition, a shorter failure recovery time can be obtained.

We developed distributed-controlled multi-layer traffic engineering system. There is no previous works that report the system. Therefore, we can not confirm feasibility and scalability of the system. In this paper, we report an experiment on our system consisting of Internet protocol (IP) routers and optical cross-connects (OXCs). In this system, control is provided by generalized multi-protocol label switching (GMPLS) and IP network topology and IP routes are dynamically reconfigured to suit traffic characteristics. These functions prevent traffic congestion as well as any decrease in link utilization rates. We had experiments to test behavior of the routers and OXCs depending on traffic characteristics. We cleared that the distributed-controlled multi-protocol label switching (MPLS)/GMPLS traffic engineering system was feasible and scalable by the experiments.

In MPLS (Multi-Protocol Label Switching) over optical networks, both the optical level and the MPLS level fault recovery can be considered. Generally, a more flexible path arrangement can be realized by the MPLS level recovery, while fast recovery can be achieved by the optical level recovery. When the optical level recovery is adopted, only normal traffic is carried through the working lightpaths and only recovered traffic is carried through the backup lightpaths. In contrast, the working LSPs (Label-Switched Paths) and the backup LSPs corresponding to other working LSPs can be accommodated into an identical lightpath when the MPLS level recovery is adopted. By such sophisticated accommodation of LSPs into the lightpaths, lightpath bandwidth can be utilized efficiently under the condition that the bandwidth utilization is restricted to attain the given objective of transfer quality for the MPLS packets in the normal state and unrestricted in a short time a failure occurs somewhere in the network. This paper proposes a simple mathematical programming model to obtain the optimum arrangement of the working and backup LSPs assuming the MPLS level recovery and a practical LSPs provisioning mode. By comparing the minimized network cost obtained from the optimum arrangement of the working and backup LSPs with the network cost resulting from the optical level recovery, this paper quantitatively evaluates the effectiveness of such bandwidth utilization improvement obtained from the MPLS level recovery and reveals that the MPLS level recovery can actually reduce the network cost due to its flexible arrangement of LSPs on the lightpaths.

Today the Internet has serious problems of an explosive increase of traffic caused by increased numbers of users. These problems degrade prominently the quality of service (QoS), and make it difficult to provide multimedia and real time services. Various technologies are proposed to solve these problems. Especially, MPLS (multiprotocol label switching) was developed for the Internet backbone network. The faults occurring in high-speed networks such as MPLS may cause massive data loss and degrade QoS. To deliver a reliable service, however, MPLS requires a set of procedures to provide a suitable protection for the traffic carried on the label switched paths (LSPs). This paper proposes an enhanced scheme for fast rerouting to preassigned LSPs in case of LSP or link failures. In order to minimize back-up resources, it allows possibility of splitting traffic of faulty LSP onto available alternative LSPs for fault recovery. We use preassigned LSPs for restoration when fault occurs. Total traffic throughput and resource utilization can be maximized if the traffic of faulty LSP is split over multiple pre-assigned LSPs. In this paper a new approach to providing fault tolerance in MPLS networks using case-based reasoning as a method to find out the amount of traffic forwarded on each pre-assigned LSP based on past experiences if loading process is presented. The pre-assigned LSPs and the percentage of traffic splitting are calculated off-line based on desired QoS and capacity constraints.

Mapping between two heterogeneous networks, Multi Protocol Label Switching (MPLS) and IEEE 802.11e is choice of future technology as it has ability to perform traffic engineering and create the corresponds between LSP (Label Switch Path) and AC (Access Category). This paper discusses the mapping between IEEE 802.11 MPLS integration to achieve quality of service on MPLS networks. MPLS and 802.11e is very useful approach for today’s internet to ensure the Quality of service the end to end. It talks about different approaches to map 802.11e Access Categories (AC) to Label Switched Path (LSP) and their advantages. It then introduces the concept of encapsulated LSPs to achieve future QoS, which requires further study to examine its practicability.