Hello,
Today, I would like to share with you this topic which Introduce the Intelligent Optical Network ASON and these services.
Since ASON (Intelligent Optical Network) is built on various transmission technologies, that is, an independent control plane is added on the transmission plane SDH and optical transmission network (OTN), so it supports all kinds of transmission network can currently provide Rate and different signal characteristics (such as format, bit rate, etc.) services.
The ASON network can provide a transmission channel with fixed bandwidth between two customer network elements. The channel is defined between the input access point and the output access point of the optical network. The ASON services has the following aspects:
SDH service, supporting SDH connection particles VC-n and VC-n-Xv defined by G.707;
OTN service, supporting OTN connection particles ODUk and ODUk-n-Xv defined by G.709;
Transparent or opaque optical wavelength service;
Ethernet services of 10Mb / s, 100Mb / s, 1Gb / s and 10Gb / s;
Storage area network (SAN) services based on Fibre Channel Connection (FICON), Enterprise System Connection (ESCON) and Fibre Channel (FC).
ASON is scalable for new services types. ASON can support multiple types of services models, and each services model has its own services attributes, target market, and services management requirements.
Services connection topology type
In order to support enhanced services (such as bandwidth on-demand allocation, diversity circuit assignment, and bundled connections, etc.), ASON should support the separation of call and connection control. The separation of call and connection control can reduce the excessive call control information of intermediate connection control nodes, and remove the heavy burden of decoding and interpreting messages. The connection topology types supported by ASON include: bidirectional point-to-point connection, unidirectional point-to-point connection, and unidirectional point-to-multipoint connection.
Due to the separation of call and connection, one call can correspond to multiple connections. Currently, bidirectional point-to-point connection is the most important connection method.
Services connection type
The ASON network supports three types of service network connections: Permanent Connection (PC), Switched Connection (SC), and Soft Permanent Connection (SPC).
Both PC and SPC connections are managed by the management plane to initiate connections. The difference between PC and SPC is whether the connection is established in the optical network using network management commands or real-time signaling. Both of these methods are service connections initiated by the operator.
The SC connection is initiated through the UNI signaling interface, and the user's service request is sent to the operator through the UNI of the control plane (including the signaling agent), that is, the user directly initiates the establishment of the service connection.
Services class
The current transmission network cannot formulate corresponding tariff policies according to service levels, resulting in waste of resource allocation, and the ASON network can easily prioritize service circuits to provide transmission service circuits with service quality agreements (SLAs). Customers have different requirements for the reliability of different connections. These requirements can be expressed in terms of "service level". In the ASON network, the service level is mainly achieved by mapping to different recovery, protection options and related connection priorities, such as establishing priority, maintaining priority (whether it can be pre-idle), and restoring priority.
The establishment priority mainly refers to the establishment response time of the services, which is to establish the services connection within days, hours or minutes, respectively.
Maintaining priority (whether it can be pre-idle) mainly refers to whether the system will be idle to carry more important services when other system failures occur, and whether the service connection itself is protected.
Recovery priority is to consider the recovery time and recovery level (such as recovery service percentage) when the system fails.
Each operator has different options to map a single service level to a series of protection and recovery options. The control plane supports the setting of link priority based on each connection, and supports bandwidth resource reservation as a restoration purpose and normalization of routes after failure repair. Generally supported service connection levels include: dedicated connection (1 + 1 and 1: 1), shared protection (1: N and M: N), unprotected (transmitted on the main circuit), unprotected service (transmitted on the protection circuit).
Service access method
In order to connect services to the ASON network, users first need to establish a physical connection with the operator's network on the transmission plane. According to the location of the operator's network and customers, service access can take intra-office access (the optical network element and the client network element are in one place), direct remote access (with a dedicated link connected to the user end), via Remote access into the subnet and dual-homing access.
ASON must support dual-homing access. When using dual-homing access for the same client device, multiple addresses should not be required. Dual-homing access is a special case of access. The main purpose of using dual-homing access is to enhance the survivability of the network. When one access fails, the customer's services can rely on another access without interruption. Customer equipment can be connected to the core network / operator in a dual-homing manner (two different paths).
From a security perspective, network resources should avoid unauthorized access. Service access control is a mechanism that restricts and controls entities' attempts to access network resources, especially through UNI and external network node interfaces (E-NNI). The connection admission control (CAC) function should support the following security features.
1- CAC applies to all entities that access network resources through UNI (or E-NNI). CAC includes an entity authentication function to prevent impersonators from fraudulently using network resources by pretending to be another entity. The authenticated entity will be assigned a service access level according to configurable policy management.
2- The UNI and Network Node Interface (NNI) should provide mechanisms to ensure customer authentication and link information integrity, such as link establishment, teardown, and signaling information, for connection management and to prevent services intrusion. UNI and E-NNI should also include CAC-based application billing information to prevent forgery of connection management information.
3- Each entity can make use of network resources through the authorization of the operator management strategy.
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