1. DWDM and OTN basic conceptual
DWDM: Dense Wavelength Division Multiplexing (DWDM) is a combination of multiple optical waves in a range of optical wavelengths and a single optical fiber in the vicinity of a window with a wavelength of 1550 nm. Laser technology for increasing bandwidth on fiber-optic backbones. More specifically, the technique is to multiplex the tight spectral spacing of individual fiber carriers in a given fiber to take advantage of the achievable transmission performance (eg, to achieve minimal dispersion or attenuation). Thus, with a given information transmission capacity, the total number of fibers required can be reduced.
OTN (Optical Transport Network) is a transmission network that organizes networks in the optical layer based on wavelength division multiplexing technology and is the next generation backbone transmission network. The OTN switching module is added in the technology, so that the system can flexibly dispatch communication services, so that the client information can be expanded, promoted, increased, and the network communication service capability is improved, thereby solving the traditional WDM network without wavelength/sub-wavelength. Poor service scheduling capabilities, weak networking capabilities, and weak protection capabilities.
2. Differences in networking and protection mechanisms
The DWDM technology networking mode is mainly point-to-point, chain, star, and ring network. Only the base layer protection is provided in the protection mode. The protection mode is mainly optical multiplex section protection, and 1+1 and 1 are adopted on the optical path. : 1 protection. The terminal device is not protected. This protection mode requires two optical cables that are independently routed. The self-healing protection of the DWDM service is performed in the SDH ring network.
The OTN networking is usually a ring network or a mesh network. It can provide line 1+1 protection, wavelength 1+1 protection, customer side 1+1 protection, ODUk protection, optical layer and electrical layer protection.
3. Business scheduling capabilities
In OTN, data configuration can be used for cross-connection (similar to SDH service configuration), which can access multiple types of services at the same time, and can realize intelligent scheduling of services. Can provide optical layer wavelength level, electrical layer sub-wavelength level service hybrid scheduling capability, optical layer scheduling capability: optical layer provides OADM wavelength scheduling mode, can pre-plan input/output fixed wavelength, can also use AWG input/output all wavelengths, The wavelength of the uplink and downlink services is connected to the service card. Electrical layer scheduling capability: Provides distributed electrical crossover of ODU0/ODU1/ODU2/ODU2e/ODU3/ODU4 particles, and the adjacent slot cross capacity reaches 100/200Gbps.
4. Different signal formats
DWDM technology does not have a corresponding frame structure. During operation, the wavelength of a single signal is converted into a corresponding wavelength in network communication through a converter, and the transmission wavelength is multiplexed by optical technology.
OTN has a complete frame mechanism. It can realize the electrical cross function similar to SDH by scheduling the wavelength by electric crossover technology, so that the signals of small particles can be combined and transmitted in a large channel. The channel of OTN also has a large size like SDH. Small and small containers, OTN has the ability to access and process from the system, improving bandwidth utilization efficiency. OTN technology can also supervise the working performance and faults of network communication and electrical regeneration. In the process of performance fault detection, OTN technology is superior.
5. Application scenario
DWDM is mainly used in the provincial trunk network and the provincial backbone network. The main method is point-to-point networking, which can realize the line protection. If the line protection mode is adopted, more lines need to be laid and the cost is high. Therefore, the self-healing protection of the DWDM service is combined with the SDH ring network and is widely used.
The OTN network has improved the ideal solution for the large-bandwidth granular service. The OTN network is deployed in the inter-provincial backbone network, the provincial backbone network, and the metro core layer of the telecom operators, and the scheduling of service particles above Gb/s is provided. The provincial backbone network carries long-distance services such as PSTN/2G/3G/4G/internet.
The OTN network can implement multiple forms of protection and has strong protection capabilities. The backbone network in the province carries services such as the NGW/3G/4G/IPTV large customer line between the backbone routers. The metro core network carries the large-granular service between the local network core router and the aggregation router, and builds the provincial backbone network OTN. And the metropolitan area network core layer OTN network.
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