Virtual Concatenation - Huawei OptiX OSN 550 Configuration Manual

OptiX OSN 550 Multi-Service CPE Optical Transmission
System
Configuration Guide
HDLC
The HDLC is a general data link control procedure. When using the HDLC protocol, the system
encapsulates data services into HDLC-like frames as information bits and maps the frames into
SDH VC containers.
LAPS
The LAPS is also a data link control procedure. It is optimized based on the HDLC. The LAPS
complies with ITU-T X.86.
GFP
The GFP is the most widely applied general encapsulation and mapping protocol. It provides a
general mechanism to adapt higher-layer client signal flows into the transport network and can
map the variable-length payload into the byte-synchronized transport path. The client signals
can be protocol data units (PDU-oriented, such as IP/PPP and Ethernet), block code data (block-
code oriented, such as Fiber Channel and ESCON), or common bit data streams. The GFP
protocol complies with ITU-T G.7041.
The GFP defines the following modes to adapt client signals:
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4.2.6 Virtual Concatenation

The rate of the Ethernet service does not adapt to the rate of the standard VC container. Hence,
if you directly map the Ethernet service data into a standard VC container, there is a great waste
of the transmission bandwidth. To solve the problem, use the virtual concatenation technology
to concatenate many standard VC containers to a large VC container that adapts to the rate of
the Ethernet service.
The concatenation is defined in ITU-T G.707 and contains contiguous concatenation and virtual
concatenation. Both concatenation methods provide concatenated bandwidth of X times
Container-N at the path termination.
Contiguous concatenation concatenates the contiguous VC-4s in the same STM-N into an entire
structure to transport. It maintains the contiguous bandwidth throughout the whole transport.
Virtual concatenation concatenates many individual VC containers (VC-12 containers, VC-3
containers, or VC-4 containers) into a bit virtual structure to transport. The virtual concatenation
breaks the contiguous bandwidth into individual VCs, transports the individual VCs, and
recombines these VCs to a contiguous bandwidth at the transmission termination point.
In the case of virtual concatenation, transport of each VC container may occupy different paths
and there may be a transport delay difference between VC containers. Hence, there are
difficulties to restore the client signal. Virtual concatenation requires concatenation functionality
only at the path termination equipment and it can flexibly allocate bandwidth. Hence, the virtual
concatenation technology is widely used.
Issue 02 (2011-06-30)
Frame-mapped GFP (GFP-F)
The GFP-F is a PDU-oriented processing mode. It encapsulates the entire PDU into the
GFP payload area and makes no modification on the encapsulated data. It determines
whether to add a detection area for the payload area, depending on requirements.
Transparent GFP (GFG-T)
The GFP-T is a block-code (8B/10B code block) oriented processing mode. It extracts a
single character from the received data block and maps the character into the fixed-length
GFP frame.
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4 Configuring Ethernet Services
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