Exfo FTB/IQS-88000 Series Power Blazer for FTB-2/2Pro/5 Manual de usuario descargar pdf (Pagina 620)

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101

Glossary

608 FTB/IQS-88000 Series

Generic Framing Procedure (GFP)

 Payload Information Field

The payload area (also referred to as payload information field)

contains the framed client signal. This variable-length field may include

from 0 to 65,535 – X octets, where X is the size of the payload header

(including the extension header, if present) and the payload FCS field

(if present).

Figure GFP-T vs. GFP-F Frames on page 601 shows the GFP-T and

GFP-F frame structures. As shown, Both GFP-T and GFP-F frame types

share a common core header, payload header, and payload FCS

(optional), and they differ in the way in which the client is mapped into

this payload area.

 Payload FCS (pFCS)

This is an optional four-octet-long frame-check sequence. It

contains a CRC-32 check sequence that is designed to validate the

entire content of the payload area. The FCS field presence is

signalled by the PFI bit located in the Type field of the payload

header. The FCS does not correct any errors; it just indicates the

presence of error(s).

In GFP-F, the transmitter encapsulates one entire frame of the

client data into one GFP frame. In this case, the basic frame

structure of a GFP client frame is used, including the required

payload header.

In GFP-T, however, rather than buffering an entire client-data

frame, the individual characters of the client signal are demapped

from the client block codes and then mapped into periodic

fixed-length GFP frames. The transparent GFP client frame uses

the same structure as the frame-mapped GFP, including the

required payload header.

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Exfo FTB/IQS-88000 Series Power Blazer for FTB-2/2Pro/5 Manual de usuario Pagina 620

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