Research and Design of user network interfaces in an Automatically Switched Optical Network

1 Introduction

The main difference between ASON and the traditional OTN is that an independent control plane is introduced to give the traditional optical network intelligence. ASON has three connection modes: permanent connection, soft permanent connection, and exchange connection. The first two methods do not require strict user network interfaces, while the latter must have clear user network interfaces, that is to say, UNI is an important indicator of implementing an exchange connection. It can also be said that it was the UNI that made ASON completely intelligent and truly automated.

2 UNI signaling

2.1 main UNI signaling functions

Customer nodes and optical nodes are not equivalent entities. optical network devices are generally located at the core of the network and provide high-capacity and fast backbone network services, while customer devices are located at the edge of the network, use existing low-bandwidth and low-cost network technologies. Therefore, Services sent from the customer's network to the optical network are generally considered as a request-type service.

UNI can implement the following functions as requested by the customer: Automatic Connection establishment, connection deletion, and connection status query and connection modification. The implementation of these functions is inseparable from signaling. Currently there are several optional Signaling Mechanisms, RSVP Resource Reservation Protocol). The expansion of the Traffic Engineering and GMPLS is favored.

2.2 UNI signaling function components and Configuration Methods

UNI consists of two functional components: UNI-C UNI client-side signaling proxy) and UNI-NUNI network-side signaling proxy, which execute UNI functions on the customer side and network side respectively.

According to the UNI-C and UNI-N are integrated in the customer network and network, the signaling configuration methods are divided into four types:

1) The UNI-C is integrated in the customer's network element, the UNI-N is integrated in the Network Element

2) The UNI-C is integrated in the customer network, while the UNI-N is located outside the network

3) UNI-C is located outside the customer network, and the UNI-N is integrated in the Network

4) UNI-C is located in the customer network yuan, UNI-N is also located in the light network yuan outside

When the UNI-C or UNI-N is outside the network element, they communicate with the network element through the ISI internal signaling interface.

UNI-C and UNI-N are integrated inside the network element,

2.3 UNI signaling transmission

At least one control channel between the UNI-C and the UNI-N is used for the transmission of UNI signaling messages, which can be implemented in an in-band or out-of-band manner. In-band signaling is generally embedded on the Data Link, while out-of-band signaling is implemented through a dedicated data link. In both cases, the control channel must support IP packet transmission, because ASON is intelligently controlled by IP addresses.

In MPLS networks, signaling is implemented in-band. Strong letters of recommendation in optical networks are implemented in out-of-band mode. The main reason is that data streams passing through OXC can be exchanged without reference to each data packet. The switching unit can be the wavelength directly, time slots and even optical fibers. Therefore, for OXC data streams, they do not have to understand the protocol stack used to control information processing. There are usually many data links between OXC, each data link is controlled using a separate signaling channel, which can cause great complexity and waste, however, if the links between OXC are implemented as a group using common signaling, the implementation complexity can be simplified. Typically, OXC control connections are implemented through an out-of-band IP network.

3 UNI design implementation background and requirements

With the rapid growth of IP traffic, IP can carry a variety of business signals, and optical communication networks are booming. optical Internet, also known as optical Internet, came into being. Its data is carried by IP addresses, large Capacity WDM multiplexing) and DWDM intensive Wavelength Division Multiplexing (DWDM) are used at the underlying layer. Therefore, IP Routers are widely used as customer network devices.

At the same time, in order to adapt to new businesses, the Internet has put forward new service methods to improve the traditional best-effort service.

The integration service is one of the main types. It uses the RSVP Resource Reservation Protocol) as the main signaling protocol. At the terminal point, the customer initiates a request carrying QoS parameters, and nodes along the way reserve resources according to customer requests.

Because the characteristics of the customer network and the optical network are different, the signaling used to control the data link is also different. To control the establishment of optical network connections, a user network and core network interface between the two networks are required for signaling transformation, expansion, and ing.

4 UNI design implementation

First, a network model composed of three nodes is simulated. The middle node is used to control the optical network node, and the UNI-N function is simulated. The other two nodes are used to simulate the UNI-C function.

Currently, no ready-to-use node simulation tools are available in the industry to implement UNI simulation in the control plane of ASON. Therefore, you need to perform some expansion and modification on your own.

The module UNI-C is added in the component module of the node to expand and map the basic RSVP messages and UNI signaling messages. After the source node is expanded, the target end is similar, but it is different in programming implementation.

For the element control node of the intermediate optical network, a UNI-N module is added to the internal component module of the node. It is used to implement the UNI network-side signaling function.

The most important and critical work is to design FSM and compile the source code for each self-added module.

Finally, the Code is compiled successfully, statistical results are collected, and simulation is run to obtain the number of signaling message packets, call success probability, error probability, and other statistical results, so as to analyze and improve the UNI signaling quality.

5 conclusion

The Module Design and Analysis of UNI in ASON are carried out. The simulation shows that this signaling design scheme is basically feasible. At present, large companies at home and abroad and well-known standardization organizations have made great efforts to research ASON. Among them, OIF is mainly committed to the research of ason uni, and UNI 1.0 is mature, now it is mainly focused on UNI 2.0 specifications. It is believed that the large-scale operation of ASON is just around the corner.

1. ASON automatic switching Optical Network Technology and Its Development
2. Research on the Control Plane of ASON automatic switching Optical Network