Nortel Networks NTRN10AN, 3500 manual GFP Encapsulation, Gfp Fcs

2-100Operation, administration, and maintenance (OAM) features

In GFP-T, client signals are decoded and mapped into GFP-T frames; these frames can be transmitted immediately without waiting for the reception of an entire client data frame. In GFP-F and GFP-T, idle frames are inserted as necessary to fill the transport payload. Multiple GFP-F frames can be aggregated in a single SONET payload.

Figure 2-40 on page 2-100shows how GFP encapsulation is executed for Transparent and Frame-mapped GFP.

Figure 2-40

GFP Encapsulation

OM1958p

Client input

Client

PM

GFP Core Header

Super blocks that consist of 8 64B/65B blocks and an error-correcting CRC

-all client data encapsulated

GFP - FCS

Transparent GFP

Used for clients where the inter-frame gaps contain important client-specific information e.g. signalling information, flow control characters Fibre Channel,

ESCON

8B/10B decode

T-GFP

encode

VCAT/	SONET/SDH
CCAT
	Virtual
mapper	conca-
	tenation
	STS-x-nv

GFP

demap

64B/65B

demap

8B/10B encode

To client

Client input

Client PM

GFP Core Header

GFP payload area comprising only client frames - not inter-frame bytes (Octet aligned)

GFP - FCS

Framed GFP

Used for packet-oriented clients

-no flow control or signalling characters between packets

Ethernet MAC frames, IP

PCS

decode

GMAC

F-GFP	VCAT/
	CCAT	Virtual
encode	mapper
		conca-
		tenation
		STS-x-nv

SONET/ SDH

GFP

demap

Replace

necessary inter-frame bytes

8B/10B encode

To client

The OPTera Metro 3500 also supports Virtual Concatenation (ITU-T G.707 compliant) with support at the STS-1-nv and STS-3c-nv SONET rates. Up to 14ms of differential delay is supported between each VCAT path.

OPTera Metro 3500 Multiservice Platform NTRN10AN Rel 12.1 Standard Iss 1 Apr 2004