TOH (Transport OverHead)

In a SONET or SDH frame, the overhead dedicated to control of data

transport between network elements (NEs).TOH comprises Section Overhead (SOH) and Line Overhead (LOH). SOH of nine octets is dedicated to the transport of status, messages, and alarm indications for the maintenance of links between add/drop multiplexers (ADMs). LOH of 18 octets controls the reliable transport of payload data in the Synchronous Payload Envelope (SPE) between any two NEs. See also ADM, frame, link, NE, octet, overhead, payload, SDH, and SONET.

• PVC
• PWE3 (PseudoWire Emulation Edge to Edge)
• PWE (PseudoWire Emulation)
• PWT-E (Personal Wireless Telecommunications-Enhanced)
• PWT (Personal Wireless Telecommunications)
• PXC (photonic cross-connect)
• PXC (photonic cross-connect)
• Q
• Q.931
• QAM (Quadrature Amplitude Modulation)
• Q band
• QCIF (Quarter Common Intermediate Format)
• QCIF (Quarter Common Intermediate Format)
• QoS (Quality of Service)
• QPSK (Quadrature, Quadriphase, or Quaternary Phase-Shift Keying)
• QPSX (Queued Packet Synchronous eXchange)
• Q series
• Q Signaling (QSIG)
• QSIG (Q Signaling)
• quadbit
• quadraplex
• Quadrature Amplitude Modulation (QAM)
• quadrature phase-shift keying (QPSK)
• quadriphase phase-shift keying (QPSK)
• quadruple play