Specifications

Installation and Operation Manual Chapter 1 Introduction
RICi-622GE Ver. 1.0 Functional Description 1-7
(1 byte) (1 byte) (1 byte) (2 bytes( (64 to 1500 bytes) (4 bytes) (1 byte)
Figure 1-5. LAPS Encapsulation Format
GFP Encapsulation
The GFP encapsulation method uses the basic frame structure shown in
Figure 1-6 .
GFP Frame
Ethernet Frame
Core Header Payload Header Ethernet Frame
(4 bytes) (4 bytes) (1500 bytes)
Figure 1-6. Basic GFP Encapsulation Format
Figure
1-7 shows the detailed structure of a basic GFP frame. The frame includes
the following fields:
• PLI – Payload length indicator
• cHEC – Core header CRC (calculated using ITU-T CRC-16 polynomial)
• Payload Area – Carries a framed PDU
• Payload Header – Header used for client PDU management
• pFCS – Optional
payload FCS (calculated using ITU-T CRC-32 polynomial).
GFP Frame
Core
Header
Payload
Area
Payload
FCS
PLI cHEC Payload Header Payload Area pFCS
(16 bits) (16 bits) (4 bytes) (framed PDU – 4 to 65535 bytes) (32 bits)
Figure 1-7. Detailed Structure of Basic GFP Frame
All GFP OAM&P functions are handled by the GFP core header.
The payload header supports the payload-specific adaptation functions, which
depend on the client application (for RICi-622GE, the client application is
Ethernet). The payload header also supports multiplexing (using extension
headers), and any application-dependent link management functions (using
dedicated client management frames)
Protection against errors (on a per frame basis) is provided by the optional
payload frame checksum (FCS) field.
Idle frames are used for asynchronous rate adaptation.