EXFO FTB/IQS-85100G Packet Blazer for FTB-500/IQS-600 - Manual (Page 398)

Glossary
388 FTB/IQS-85100G
Generic Framing Procedure (GFP)

Payload FCS Indicator (PFI): A one-bit subfield indicating the
presence (1) or absence (0) of the payload FCS field. The following
table lists the currently defined PFI values.

Extension Header Identifier (EXI): A four-bit subfield identifying
the type of GFP extension header. Three kinds of extension
headers are currently defined:

User Payload Identifier (UPI): An eight-bit field identifying the
type of payload conveyed in the GFP payload information field:
PFI Description
0 FCS Absent
1 FCS Present
EXI Description Function
0000 Null Extension
Header
Indicates that no extension header is present.
0001 Linear Extension
Header
A two-octet extension header that supports sharing of the GFP payload across
multiple clients in a point-to-point configuration. The linear extension header
consists of an eight-bit channel ID (CID) field, used to indicate one of 256
communication channels (i.e. clients) at a GFP termination point, and an
eight-bit spare field reserved for future use.
0010 Ring Extension
Header
The use of this field is under consideration. Similar to linear, the current proposal
being considered is to allow the sharing of the GFP payload across multiple
clients;
however, this would only apply to ring configurations.
0011
to
1111 Reserved
UPI Client Data Client Management
0000 0000
1111 1111 Reserved and not available Reserved
0000 0001 Mapped Ethernet Frame Client Signal Fail (Loss of Client Signal)