Synchronous Optical Networking - SONET/SDH Network Management Protocols

SONET/SDH Network Management Protocols

See also: Telecommunications Management Network

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SONET equipment is often managed with the TL1 protocol. TL1 is a telecom language for managing and reconfiguring SONET network elements. The command language used by a SONET network element, such as TL1, must be carried by other management protocols, such as SNMP, CORBA, or XML. SDH has been mainly managed using the Q3 interface protocol suite defined in ITU recommendations Q.811 and Q.812. With the convergence of SONET and SDH on switching matrix and network elements architecture, newer implementations have also offered TL1.

Most SONET NEs have a limited number of management interfaces defined:

Electrical interface

The electrical interface, often a 50-ohm coaxial cable, sends SONET TL1 commands from a local management network physically housed in the central office where the SONET network element is located. This is for local management of that network element and, possibly, remote management of other SONET network elements.

Craft interface

Local "craftspersons" (telephone network engineers) can access a SONET network element on a "craft port" and issue commands through a dumb terminal or terminal emulation program running on a laptop. This interface can also be attached to a console server, allowing for remote out-of-band management and logging.

Data communication channels (DCCs)

SONET and SDH have dedicated data communication channels (DCCs) within the section and line overhead for management traffic. Generally, section overhead (regenerator section in SDH) is used. According to ITU-T G.7712, there are three modes used for management:

• IP-only stack, using PPP as data-link
• OSI-only stack, using LAP-D as data-link
• Dual (IP+OSI) stack using PPP or LAP-D with tunneling functions to communicate between stacks.

To handle all of the possible management channels and signals, most modern network elements contain a router for the network commands and underlying (data) protocols.

The main functions of network management include:

Network and network-element provisioning

In order to allocate bandwidth throughout a network, each network element must be configured. Although this can be done locally, through a craft interface, it is normally done through a network management system (sitting at a higher layer) that in turn operates through the SONET/SDH network management network.

Software upgrade

Network-element software upgrades are done mostly through the SONET/SDH management network in modern equipment.

Performance management

Network elements have a very large set of standards for performance management. The performance-management criteria allow not only monitoring the health of individual network elements, but isolating and identifying most network defects or outages. Higher-layer network monitoring and management software allows the proper filtering and troubleshooting of network-wide performance management, so that defects and outages can be quickly identified and resolved.