ASB: IP-oriented smart Optical Network

The introduction of intelligent optical networks to carry IP addresses can effectively simplify the network structure, greatly reduce the overall investment cost of the network, and significantly improve the scheduling capability, maintainability, reliability, scalability, and service QOS.

With the rapid growth of the IP service, the demand for network bandwidth far exceeds the traditional voice network, which greatly increases the network capacity and the capacity of each optical fiber reaches the Tbit/s level, the node needs to process dozens or even hundreds of wavelengths. At the same time, the number of nodes is also increased several times, and nodes often need to be directly interconnected through optical waves. network topology MESH is an inevitable trend. This new feature also shows that the IP service has higher requirements on the service scheduling capability, maintainability, reliability, and scalability of the bearer network. The burstable and uncertain IP service requires the network to have the scheduling capability of various service levels to quickly provide services and optimize network resources. As the network scale expands, network maintenance and management are also facing new challenges. To meet the QoS requirements of IP services, the bearer network must be able to provide services with Different reliability levels, new requirements are put forward for the reliability of the bearer network. As the network size expands, the network also requires good scalability to avoid the negative impact of the new network on the original network.

The IP network transmission structure needs to be optimized

Traditional IP networks are the best-effort networks. They are designed to provide basic Internet services. They do not have to ensure strict QoS or consider the extra bandwidth required for fault recovery, therefore, the bandwidth utilization may reach a high level. The new generation of telecom-grade IP networks must be a unified multi-service grouped transmission platform for voice, video, data, and new services that may emerge in the future, the development of a carrier-level IP network with QoS Assurance has become an inevitable requirement of operators.

The current IP network construction scheme is to classify the data network, which is carried by DWDM or directly connected through optical fiber. Multiple routers need to be transferred between the source and destination of the IP packet, which will generate a large number of direct services, that is, services that are not directly transferred locally (Direct Business can account for 60% of the total processing capacity of a core router), which leads to a large amount of additional costs, even the core router with the maximum capacity will soon face expansion problems. Currently, the clus-ter method is used to expand IP Routers. the interconnection between devices in the same location is expensive and the network is often blocked. In addition, the Core IP network adopts a dual-route backup (link backup, node backup) networking structure, resulting in a doubling of network investment by operators. Therefore, the current IP network is extremely light, and the bandwidth utilization of the backbone network link is only 10% ~ 30%. Designing a new cost-optimized IP network transmission structure has become a hot topic in the industry.

Introduce ASON

The intelligent optical network technology is defined as ASON by ITU-T, which introduces dynamic switching and intelligent control capabilities in the traditional static optical network, so that the transmission network can evolve from the bearer network to the service network.

* Intelligent: provides fast network services and new profit growth points, such as optical Virtual Private Network (OVPN), business traffic engineering (TE), and triple play (TriplePlay; improve Service survivability and effectively defend against multiple network faults, and truly reach more than 99.999% of telecom-level business levels;

* Standardization: network interoperability in multi-vendor and multi-carrier environments is achieved through standardized protocols and interfaces;

* PERSONALIZATION: flexibly provides different service levels to meet the needs of rapidly growing Differentiated Services (Diff-Serv;

* Simplicity: This feature enables automatic service protection and topology discovery, reduces manual configuration workload, and fully reduces maintenance difficulty.

Simplified networking

With the rapid development of video, data P2P, and P2MP services, IP services are transformed from centralized aggregation to distributed uniform services. The corresponding IP network tends to be flat, and each two ROUTER is connected through a direct transmission channel, forming a logical mesh network, core and convergence on the VC4 layer, not strictly layered. This avoids the emergence of super-core nodes and simplifies the configuration and management of IP/MPLS networks. The Router does not need to configure multi-hop routes. This structure can reduce maintenance costs and greatly improve network robustness.

IP router mesh network interconnection can avoid a large number of direct-through services generated by intermediate nodes, but the optical fiber or DWDM virtual fiber mesh direct-connection IP layer is not easy to maintain, high cost, low link efficiency, however, ASON can be used to build a logical mesh network with VC4 as particles on the first layer for IP addresses to effectively fill the fiber link. The actual application shows that the capacity of the direct link between most nodes in the network is less than 2.5 Gbps.

Reduce overall investment costs

Considering that the market price of the core router with the same I/O port is five times that of the SDH device, the ASON can provide a direct connection channel on the VC4 layer, and the router can form a logical mesh network, transfers the layer-3 Processing of the pass-through service to layer-1 to save the capacity and port (especially the long distance port) of the router ). ASON provides layer-1 protection/recovery. layer-3 routers do not need to reserve a large amount of capacity for service recovery, and do not need to use dual-plane (link, node) Protection modes. Avoid router stacks and super core nodes.

In the traditional mode, the IP network adopts a multi-layer architecture, and the pass-through service needs to jump to the destination, consuming a lot of L3 resources on the intermediate router. As a result, many backbone nodes need to be resized. The clustering method is too expensive and will introduce blocking. In practice, only three to four interconnected nodes are supported, while the Terabit router is more expensive.

Using ASON to carry IP addresses can significantly reduce the overall investment cost, especially the investment cost of routers.

Improve service QoS

The multi-layer structure of the traditional IP network introduces multi-hop and additional latency, which has a great impact on the QoS of some services, especially for global VoIP communication (≥0. 150 ms ). However, 0.99998 of the end-to-end service reliability (e.g. VoIP) requires higher backbone network reliability, and the current IP network is hard to meet the requirements.

The IP network carried by ASON can improve service QoS: Facilitate Fault Locating and improve network management capabilities; reduce service damage time (through layer-1 protection/recovery); layer-1 (instead of layer-3) reduces latency (nodes and links), reduces jitter, and reduces packet loss rates. Reduces the frequent update of router route tables due to faults.

New business and application

ASON can provide BOD services (UNI1.0, 2.0), dynamically request bandwidth through the UNI interface, improve network utilization, and avoid the traditional maximum service configuration (port, matrix) mode, this reduces the router capacity and ports and improves the bandwidth utilization of the transmission network. ASON can allocate OVPN for connections between IPTV, NGN, Softswitch, 3G bearer, IDC interconnection, and public INTERNET service nodes to share the same physical transmission network.

With the rapid growth of the IP service, the demand for network bandwidth far exceeds the traditional voice network, which greatly increases the network capacity and the burst and uncertainty of the IP service, the network will be required to have wavelength-level scheduling capabilities to quickly provide services and optimize network resources. The VC4 matrix is transformed into an ODU matrix through software upgrades to provide cross-connection capabilities for 256 wavelength channels.

Network Maintenance

ASON provides more powerful fault detection capabilities to simplify network maintenance and reduce maintenance costs. ASON can defend against multiple link faults, greatly improving network robustness. ASON provides end-to-end channel scheduling capabilities, making Service Activation faster.

ASON supports a wide range of protection recovery types and business priority levels to defend against various link faults and effectively carry services with different QOS requirements of IP addresses.

Combined with protection and recovery, PRC provides permanent 1 + 1 protection. Two NORMAL circuits are established between the source node and the target node, which are used as the primary and standby routes respectively. The two circuits do not pass through the shared risk link group (SRLG ), when a network failure leads to a route failure, the service is automatically switched to another route within 50 ms, and the recovery mechanism is enabled at the same time to find and establish another protection route. After the network fault is finally restored, the primary route and the standby route will return to the original NORMAL route. Improve the reliability of the network layer: <50 ms, the route table will not change because of link failure.

1 + 1 Protection provides replacement of less than 50 ms in the event of a fault.

The recovery mechanism (re-routing) temporarily creates a protection path to protect your business. The recovery mechanism is divided into two types based on whether to calculate the standby route ahead of schedule: guaranteed GUARANTEE recovery (pre-computed protection route); source-based recovery (after the master service is interrupted, the protection route is calculated ).

Based on the definition of the network protection type, a maximum of five priority levels can be customized for the network. When a fault affects multiple services at the same time, high-level services are restored first. If the idle network resources are insufficient, high-level services are restored and low-level services are lost. When there are no idle resources, high-priority services can seize resources of low-priority businesses. network faults are fixed, multiple businesses with different priorities can return the initial route.

In summary, using ASON to carry high-quality IP networks can simplify networking, reduce comprehensive investment costs, improve service QOS, and simplify network maintenance and introduce new services and applications.