New Generation Optical Network networking technology

Hung Lian 95 Information Industry Co., Ltd. Chen Jinzhang

In recent years, communication network technology has been developing rapidly with the combination of computer network technology represented by Internet, among which communication, computer, radio and television are the basis of the integration of optical communication technology more attention of the world. Optical network expert, Hung Lian 95 chief engineer Mr. Chen Jinzhang the next Generation Optical network technology is elaborated.

DWDM, all optical network development, so that the transmission capacity doubled every 12-18 months. However, the management and control of optical network is still in the traditional mode, optical network only as a transmission medium to support the development of communication services. This kind of traditional transmission service and Communication Service control and management mode, so that the current broadband channel is still the provision of static configuration, not in time to provide all types of business needs of bandwidth. In addition, it can not dynamically use a variety of network resources including PDH, sdh/sonet, DWDM, etc., which affect the flexibility of network organization, the validity of network and the expansion of new business. To this end, international standardization agencies such as ITU-T, OIF, ODST and IETF have proposed the draft of automatic switching transmission network (ASTN)/automatic Switched Optical Network (ASON) and Universal Multiprotocol marking Exchange (GMPLS) standards or standards.

Two models of interconnection

A network in the overall function, can be data (or transmission) plane, control plane, management plane composition. The control plane mainly involves the establishment of connections and the processing needed to support such connections, such as Discovery/link management, signaling, routing, addressing, and the provision and protection of network channels within the routing domain. In general, the control plane is implemented by IP technology, and the management plane provides network and equipment management for the provider and the management department. The data (or transmission) plane is used to transmit and forward data to and from customers inside and outside the network. Obviously, these three planes are interrelated. IP over optical network structure is essentially defined by the organization of the control plane, and the control plane of IP and optical transmission network can be loosely coupled, and can be tightly combined. This combination determines the degree of detail of the optical network through the User network Interface (UNI) channel topology and routing information, the IP router chooses the control level of the special link channel in the Optical Network, and the related strategy of dynamically providing the optical channel between routers, which includes the problem of access control and security. There are two interconnected models, namely overlapping models and peer-to-peer (or integrated) models.

The basic characteristic of overlapping model is that the protocols used in the optical transmission level, such as signaling, addressing, routing and so on, are different and independent from each other, such as signaling, addressing and routing establishment. It has the upper and lower levels, the upper layer is the lower level of the customer, the lower layer is the top provider, between the two necessary information exchange through the optical network of the User network Interface (UNI). Astn/ason is an intelligent optical network structure, which belongs to overlapping model. It provides dynamic connectivity including sdh/sonet, wavelength and future optical connections, and can arrange bandwidth as needed. IP Services can be implemented on the basis of sdh/sonet, wavelength and optical connections. It can provide a variety of business, easy to develop new business (including Virtual private network), have better networking flexibility. The development of this model is based on the fact that: at present, many telecommunication operators ' optical transmission network part is divided into two or more different operators, and the optical transmission network operators may have to serve multiple service exchange network operators, they are willing to work with the business Exchange Network operators in the division of equipment and functions have a clear boundary, Do not want to provide their own internal network information to other people to share. This kind of function is distinct and has the characteristic of stratification, it is the main characteristic of overlapping model.

The Peer-to-peer model unifies the control plane of the optical transmission network level and the Service Exchange network level, uses the unified control plane, from the control point of view, they are equal, does not divide the upper and lower level, its addressing, the signaling, the route establishment and so on uses the protocol is also same. In this model, the optical layer and the business level of the equipment used is also equivalent, such as optical crossover devices (OXC) and routers are also considered equivalent, is currently very popular, and the development of GMPLS on the use of this model. GMPLS has been successfully applied to IP communication network based on the MPLS, GMPLS make the network more flexible, all kinds of net resources can be effectively used (including control plane resources), promote optical transmission network and Business Exchange network integration, for the development of new business to create good conditions.

Currently, the industry is developing a light control plane that integrates the powerful hardware capabilities of the data plane with the intelligent control plane, which combines IP routing technology with MPLS on the optical layer.

GMPLS is developed by the IETF Computer Communication network experts, the current people of Gmpls consistent optimistic, but there are many problems to be solved. Now that GMPLS is only in the draft standard, there is a long way to go before a broad consensus can be reached and standards are established. Astn/ason mainly by the ITU-T Communication network experts developed, has initially formed a standard, relative to gmpls more mature, China is also developing the project. Astn/ason will be developed in the near future, in the long run, Astn/ason and GMPLS will not have more contradictions, Astn/ason external interface has been taken into account with the Gmpls interface, the relevant agencies are starting to study the two further problems of convergence.

GMPLS is an extension of mpls-te

As noted earlier, GMPLS employs a peer-to-peer model, developed on the basis of MPLS, and, more accurately, Gmpls is mpls-te extension, Mpls-te is an extension protocol for MPLS-supported traffic engineering, and the GMPLS's core extension is:

An MPLS or Mpls-te control plane that only provides packet switching (PSC) and second-tier switching (L2SC) interfaces. GMPLS expands the interface of this control plane, which includes not only PSC, L2SC, Time Division Multiplexing (TDM), wavelength switching (LSC), and Fibre Exchange (FSC). In contrast to this interface, the GMPLS transfer (or data) plane should include PSC, L2SC, TDM, LSC, and FSC.

The focus of GMPLS work is the setting of the control plane. It unifies PSC, L2SC, TDM, LSC, and future FSC control planes, including the use of unified signalling and path-building methods. These 5 kinds of PSC, L2SC, TDM, LSC, FSC Exchange level are independent and reciprocal.