Huawei OptiX OSN 550 Configuration Manual page 170

4 Configuring Ethernet Services
Virtual concatenation is available in two types: virtual concatenation in a higher order path and
virtual concatenation in a lower order path. A higher order virtual concatenation VC4-Xv
provides a payload of X Container-4s (VC-4s). The payload is mapped individually into X
independent VC-4s. Each VC-4 has its own POH. A lower order virtual concatenation VC-12-
Xv provides a payload of X Container-12s (VC-12s). The payload is mapped individually into
X independent VC-12s. Each VC-12 has its own POH. It is the same case with the virtual
concatenation of VC-3s.
VC4-Xv and VC-3-Xv
The virtual container that is formed by a VC4-Xv/VC-3-Xv can be mapped into X individual
VC-4/VC-3s that form the VC4-Xv/VC-3-Xv. Each VC-4/VC-3 has its own POH. POH has the
same specifications as the ordinary VC-4 POH. The H4 byte in the POH is used for the virtual
concatenation-specific multiframe indicator (MFI) and sequence indicator (SQ).
MFI indicates the position of a frame in the multiframe. Each frame sent by the source carries
the MFI information. The sink end combines the frames with the same MFI into the C-n-Xv.
MFI includes MFI-1 and MFI-2. MFI-1 is transmitted by bits 5-8 of the H4 byte and ranges from
0 to 15. MFI-2 is transmitted by the two frames of which the MFI-1 is "0" and "1" in the
multiframe. Bits 1-4 of the H4 bytes of the two frames indicate the higher four bits and lower
four bits of the MFI-2 respectively. Hence, the MFI-2 ranges from 0 to 255. That is, a multiframe
consists of 4096 frames and the period is 512 ms.
SQ indicates the position of a frame in the C-n-Xv. The source end inserts the SQ information
into the frame according to the payload allocation sequence. The sink end determines the
sequence to extract the payload from the frames that form C-n-Xv according to the SQ. SQ is
transmitted by the two frames of which the MFI-1 is "14" and "15" in the multiframe. Bits 1-4
of the H4 bytes of the two frames indicate the higher four bits and lower four bits of the SQ
respectively.
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OptiX OSN 550 Multi-Service CPE Optical Transmission
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System
Configuration Guide
Issue 02 (2011-06-30)