We have developed a GMPLS-based software platform with Intelligence Optical Network (ION) capabilities to simulate different technologies and protocols of ASTN. For optical transport network (OTN) based ASTN, usually named as automatically switched optical network (ASON), two signalling schemes, Explicit Label Control (ELC) and Backward Wavelength Reservation with N retries (BWR-N), are considered. The ELC is associated with two routing and wavelength assignment (RWA) policies, the shortest path first routing (Dijkstra algorithm) with first-fit (FF) wavelength assignment and the fixed path least congestion (FPLC) routing with FF wavelength assignment. For the BWR-N, the route is determined by Dijkstra's algorithm and the wavelength is selected through signalling process. For SDH/SONET-based ASTN, we also consider two signalling scheme, the ELC and the Forward Timeslot Reservation (FTR). Similar simulations have been performed. These signalling and routing schemes are evaluated by several crucial metrics, such as the blocking probability, the setup time, the average routing length of the connections and the control overhead. Some significant conclusions have been presented by this paper.
Disruptive all-optical switching and ultra-long reach WDM transmission technologies enable all-optical networks without OEO conversion along paths that can span thousands of kilometers. Coupled with advances in automatic discovery, distributed routing and signaling mechanisms, the next generation all-optical intelligent networks (AOIN) has been one of the most promising technology innovations. Based on the particular PXC structure, this paper addresses in detail the process of AND in AOIN, which includes three major periods. As far as the simulation is concerned, a GMPLS-based software platform built by us can demonstrate the AOIN performance, and a meaningful result is derived when comparing the speeds of AND under different monitoring schemes.
In this paper, we propose four different RWA schemes which are introduced into the wavelength-routed intelligent optical networks. FSP+FF and FPLC+FF are traditional RWA schemes used in the centralized control environment. The other two schemes, FWR-4 and BWR-3, are distributed wavelength reservation protocols which invoke the GMPLS REVP-TE. These schemes are emulated in GMPLS-based NSFNET. The results are compared in terms of four performance metrics which are blocking probability (BP), route length (RL), setup time (ST) and control overhead (CO). Except for FWR-4, the BPs of the other three RWA schemes are similar, and in the case of lighter traffic load the BP of FPLC+FF is the smallest, but under heavier traffic load the BP of BWR-3 is the best. Because FPLC+FF does not always choose the shortest path compared with other RWA schemes using the shortest path routing algorithm, so its RL is the longest. The route and wavelength are determined by the source node, and the RL is shorter, therefore the lightpath setup in FSP+FF is the fastest among all schemes. In addition, the CO of FWR-4 is the fewest because it need not flood the routing information and retry. Though the four schemes respectively have their advantages, the performance of BWR-3 is outstanding among them if its ST can be accepted.
In this paper, according to the ITU-T recommendation G.8080, we present a novel architecture of RC based on the extended GMPLS, which consists of interface component, OSPF-TE component, route computation component and routing information database. The RC is emulated in the ASON simulation software developed by us, where the OSPF is extended as the routing protocol and GMPLS RSVP-TE is adopted as signalling protocol. In the simulation, the RWA scheme, the fixed shortest path routing way and first fit wavelength algorithm, is used. The simulation results of RC have been presented in terms of flooding time (FT), flooding overhead (FO) and route computing time. The FT and FO just have a very little change under different traffic load, which indicates that re-flooding is rare and the RC works efficiently.
In this paper, we examine the QoS issues in the intelligent optical network (ION), and specially focus on the QoS implementation scheme associated with the control plane. Referring to the QoS models in IP networks, we propose the optical IntServ QoS model using in metropolitan optical networks, and the optical DiffServ QoS model using in core optical networks. The networks to support optical IntServ QoS model must deal with each traffic request for QoS assurance, then compute routes and establish lightpaths. In the optical DiffServ QoS model, core networks only accept the limited classes of QoS requests. Therefore traffic flows with similar QoS requirements from the metropolitan networks must be aggregated, and then core networks provide tunnels for them. It increases the scalability of networks. In the end, this paper presents the generalized control plane architecture of the node in ION, which is based on extended GMPLS and able to guarantee subscriber’s QoS using two optical QoS models.