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Applications and Overview of Generic Framing Procedure (GFP). Mike Scholten (AMCC) e-mail: mscholten@amcc.com

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applications and overview of generic framing procedure gfp

Applications and Overview ofGeneric Framing Procedure (GFP)

Mike Scholten (AMCC)

e-mail: mscholten@amcc.com

New ITU-T standard, G.7041 describes a Generic Framing Procedure (GFP) which may be used for efficiently mapping client signals into and transporting them over SONET/SDH or G.709 links. This presentation provides an overview of network applications which have driven the development of the GFP standard within T1X1.5 and ITU-T SG15. Applications are related to some of the features included in G.7041.

This contribution is intended only to provide introductory background to G.7041 and does not make any proposals not already reflected in the standard. Previewing this contribution may help in understanding motivation behind and application of the capabilities included in G.7041.

what is gfp
What is GFP?
  • Emerging new standard for Data Encapsulation
  • Accept any client, encapsulate in simple frame, transport over network
  • Uses length/HEC frame delineation of variable length packets
  • Allows multiple data streams to be transported over single path
    • Packet aggregation for router applications
    • Common encapsulation of different client data types (e.g. Ethernet, HDLC)
  • Transparent Mapping supports LAN/SAN extension over WAN
  • Extension headers support various network topologies
    • Null Extension Header for channelized Point-to-Point network
    • Linear Extension Header for Port Aggregation over Point-to-Point network
    • Ring Header for Resilient Packet Ring applications (removed to Living List)
basic gfp frame structure

Payload Type MSB

Payload Type LSB

Ext Hdr Byte n

Ext Hdr Byte 1

Ext Hdr Byte 2

eHEC MSB

eHEC LSB

tHEC MSB

tHEC LSB

cHEC LSB

FCS[23:16]

Length MSB

Length LSB

FCS[15:8]

FCS[31:24]

FCS[7:0]

cHEC MSB

Core Header

Payload Header

Payload

Area

Payload

Basic GFP Frame Structure

Optional

Extension

Header

FCS (optional)

application packet routing through big fat pipes
Application: Packet Routing through Big Fat Pipes
  • Packet Switch encodes/decodes 8B/10B and routes packets to appropriate SPI-n
  • SONET/SDH Mapper encapsulates packets using PPP over GFP and maps them into concatenated payload (STS-48c/VC-4-16c or STS-192c/VC-4-64c)
    • Alternative to POS using PPP or EoS/LAPS using PPP
    • Avoids indeterminate bandwidth expansion due to HDLC transparency processing
  • All packet switching in WAN handled by Layer 2 routing
  • Single traffic type aggregated in edge switch & routers into big-fat-pipes going to desired hop in routing table
  • Control info from 8B/10B encoding not preserved
  • Relies on PPP for Link Configuration

Edge Switch

OC-48

STM-16

SONET

SDH

Mapper

Packet

Switch

Router-based

WAN

SPI-3

N x GbE

SPI-4

OC-192

STM-64

SONET

SDH

Mapper

gfp frame ppp packet routing via gfp

Payload Type MSB

Payload Type LSB

tHEC MSB

tHEC LSB

cHEC LSB

Length MSB

Length LSB

cHEC MSB

FCS[7:0]

FCS[15:8]

FCS[31:24]

FCS[23:16]

Core Header

Payload Header

Payload

Area

PPP

Packet

Payload

GFP Frame: PPP Packet Routing via GFP

FCS (optional)

application port aggregation over digital wrapper
Application: Port Aggregation over Digital Wrapper

Edge Switch

OTN

Mapper

OTU-1

Packet

Switch

DWDM

WAN

SPI-3

N x GbE

SPI-4

OTU-2

OTN

Mapper

Packet Switch encodes/decodes 8B/10B and routes packets to appropriate SPI-n

OTN Mapper encapsulates packets using GFP with extension header and aggregates them into OPU-n payload.

Single or multiple traffic types may be aggregated in edge switch onto single wavelength

Control info from 8B/10B encoding not preserved

gfp frame packet aggregation over otu n

Payload Type MSB

Payload Type LSB

tHEC MSB

Channel ID

eHEC MSB

tHEC LSB

eHEC LSB

Spare

cHEC LSB

FCS[15:8]

Length MSB

Length LSB

FCS[7:0]

FCS[31:24]

FCS[23:16]

cHEC MSB

Core Header

Payload Header

Payload

Area

Packet

Payload

GFP Frame: Packet Aggregation over OTU-n

Linear

Extension

Header

FCS (optional)

application resilient packet rings
Application: Resilient Packet Rings

Ring

Node

8B/10B

Client

OC-m

STM-n

GbE

MAC

Network

Process.

&

Switch

SONET

SDH

Mapper

Framer

SPI-n

SPI-n

Ring

Node

Packet

Ring

Packet

Stream

HDLC

Proc.

Ring Node

Ring

Node

  • Multiplex packet streams into single STS-Nc / VC-4-Xc
  • Each packet encapsulated into GFP Frame
  • Payload Type ID in payload header supports multi-service applications
  • Allows spatial reuse (packet statistical muxing, rather than TDM at each node)
  • GFP Extension headers support RPR
    • Ring Node addressing
    • Class of Service packet prioritization
  • 802.17 RPR WG developed alternative to GFP extension Ring Header:
    • RPR MAC generates/processes non-GFP ring header which is presented to GFP as part of payload

Packet Add/Drop

gfp frame rpr using gfp ring header

DE

DestPort

Payload Type MSB

Payload Type LSB

Spare

SrcPort

Dest MAC[47:40]

Dest MAC[39:32]

Dest MAC[31:24]

Dest MAC[23:16]

Dest MAC[15:8]

Src MAC[47:40]

Src MAC[39:32]

Src MAC[31:24]

Src MAC[23:16]

Src MAC[15:8]

Dest MAC[7:0]

CoS

Src MAC[7:0]

eHEC MSB

tHEC MSB

eHEC LSB

tHEC LSB

Spare

TTL

cHEC LSB

FCS[31:24]

FCS[15:8]

Length MSB

FCS[7:0]

cHEC MSB

FCS[23:16]

Length LSB

Core Header

Payload Header

Payload

Area

Packet

Payload

GFP Frame: RPR Using GFP Ring Header

Ring

Extension

Header

FCS (optional)

NOTE: GFP Ring Header removed to Living List; 802.17 RPR proposes to include ring header as part of GFP payload).

application extending lan san over wan

GbE

FC

GbE

FC

GbE

FC

GbE

FC

GbE

FC

SONET

SDH

Mapper

Framer

SONET

SDH

Mapper

Framer

Application: Extending LAN / SAN over WAN

8B/10B

Client

SONET / SDH

Network

STS-m

STM-n

SONET

SDH

Mapper

Framer

LAN /

SAN

STS-m

STM-n

8B/10B

Clients

8B/10B

Client

  • Want to preserve individual 8B/10B block-coded channels, but…...Cannot fit two 1.25 Gb/s GbE channels into a single OC-48 / STM-16
  • Transport of single 1.25 Gb/s stream over OC-48 / STM-16 is excessively wasteful.
  • Need to preserve control info (e.g. link configuration) for LAN extension, so……Cannot just send data packets.
  • Cannot just interleave two streams into single path and still expect SONET/SDH to deliver to different destinations.
san transport through right sized pipes using vc gfp
SAN Transport through Right-Sized Pipes using VC/GFP
  • Transparent Encapsulation / Decapsulation preserves Control Info
  • Virtually-concatenated paths sized to fit individual client signals
  • Client signals preserved intact through the network
  • Signals routed by switching VC paths (STS-1/VC-3 or STS-3c/VC-4 switching)
  • Mix of protocols may be carried, each in its own VC path
  • Virtual Concatenation (VC) essential to compete against SAN over dark fiber

N x

Fibre Chan,

GbE,

FICON,

ESCON

SONET/SDHSwitched

WAN

SAN - WAN PHY

OC-48/STM-16 or

OC-192/STM-64

SONET

SDH

Mapper

with VC

8B/10B

Codec

Transparent

Encapsulate

/ Extract

solution vc transparent gfp
Solution: VC + Transparent GFP
  • Use Virtual Concatenation (VC) to partition SONET/SDH link into “right-sized” pipes
  • “Right-sized” is smallest number of STS-3c/VC-4 or STS-1/VC-3 needed for client
  • Compress 8B/10B client without losing control information
  • Encapsulate compressed client signal into standard adaptation mechanism (GFP)
  • T1X1.5/2000-046 (Jul-2000) established target VC-path sizes for various clients:
    • Gigabit Ethernet
      • 1000 Mb/s; 1250 Mb/s 8B/10B block-coded fit into STS-3c-7v or VC-4-7v
      • 2 STS-3c/VC-4 available after 2 GbE signals VC-mapped into OC-48/STM-16
    • Fibre Channel and FICON
      • 850 Mb/s; 1062.5 Mb/s 8B/10B block-coded fit into STS-3c-6v or VC-4-6v
      • 4 STS-3c/VC-4 available after 2 Fibre Channel signals VC-mapped into OC-48/STM-16
    • ESCON
      • 160 Mb/s; 200 Mb/s 8B/10B block-coded fit into STS-1-4v or VC-3-4v
      • 12 ESCON signals can be VC-mapped into OC-48/STM-16
solution vc transparent gfp cont
Solution: VC + Transparent GFP (cont.)
  • T1X1.5/2001-04R1 (Jan-2001) established 64B/65B compression scheme:
    • Map 8-bit data directly into 64-bit block with pre-pended SyncBit = 0
    • Map 12 control characters into 3-bit location + 4-bit control code
transparent gfp mapping cont
Transparent GFP Mapping (cont.)
  • 12 8B/10B “Special Characters” remapped to 4-bit codes as shown
  • 10B Violations mapped as “10B_ERR” (RD errs, unrecognized 10B codes)
  • Rate adapt by inserting “65B_PAD” code
gfp encapsulation of n x 536 520 superblocks
GFP Encapsulation of N x [536,520] Superblocks
  • Encapsulate N x [536,520] superblocks into standard GFP Frames
    • Relocate leading “sync bits” of 8 x 65B blocks to end of 8 x 64-bit blocks
    • Compute & append CRC-16 after 8 x 65B blocks to create [536,520] superblock
    • [536,520] superblock maintains byte alignment
    • Choose N to fit available bandwidth of selected virtually-concatenated path
    • Scramble Payload Area using self-synchronous x43+1 scrambler

Leading Bit

8 byte block

8 x 65B blocks = 520 bits

1. Group 8 x 65B blocks

2. Rearrange Leading Bits at end

3. Generate & append CRC-16 checkbitsto form [536,520] superblock.

4. Pre-pend with GFP core & payload headers.

5. Scramble payload header & payloadwith x43+1. (Core header not scrambled.)

6. Form GFP frames with N x [536,520]superblocks.

N x [536,520] Superblocks

Payload Header (4 bytes)

Optional FCS (4 bytes)

Core Header (4 bytes)

handling 8b 10b disparity
Handling 8B/10B Disparity

STS-m

STM-n

STS-m

STM-n

8B/10B

Client

Transp.

GFP

Mapper

Framer

Transp.

GFP

De-map

8B/10B Client

Client

Source

Client

Sink

SONET / SDH

Network

  • 1.25Gb/s GbE,
  • 1.0625Gb/s FCor FICON,
  • 200Mb/s ESCON

Client Ingress

Client Transport

Client Egress

  • Ingress Code Violations Detected:
  • Invalid Codewords
  • Running Disparity Errors
  • Map 10B_ERR into GFP Frame.
  • Egress Codeword Generation:
  • Generate correct disparity.
  • Prevent disparity error propagation acrossdata packets.
  • Handle received 10B_ERR.
signal fail handling in transparent mapping
Signal Fail Handling in Transparent Mapping

STS-m

STM-n

STS-m

STM-n

8B/10B

Client

Transp.

GFP

Mapper

Framer

Transp.

GFP

De-map

8B/10B Client

Client

Source

Client

Sink

SONET / SDH

Network

  • 1.25Gb/s GbE,
  • 1.0625Gb/s FCor FICON,
  • 200Mb/s ESCON

Client Ingress

Client Transport

Client Egress

  • Signal Fail Handling on Egress:
  • Locally detected Signal Fail
    • Section / RS defects (LOS, OOF/LOF, RS-TIM)  10B_ERRs
    • Line / MS defects (AIS-L)  10B_ERRs
    • Path defects (LOP-P, PLM, UNEQ, MS-TIM)  10B_ERRs
    • VC-Path defects (dLOM, dSQM, dLOA)  10B_ERRs
    • GFP Frame Sync Loss  10B_ERRs
  • Received Signal Fail conditions
    • GFP_CSF 10B_ERRs
  • Handling of non-failure errors
    • Errored 8 x 65B Superblock  8 x 8 10B_ERR chars
    • Non-decodable 65B Block  8 x 10B_ERR chars
  • Signal Fail Conditions on Ingress:
  • Protocol-specific Client Signal Failures
    • Loss of Signal  GFP_CSF
    • Loss of Synchronization  GFP_CSF

Definitions:

GFP_CSF = GFP Client Mgt Frame with Client Signal Fail Indication

10B_ERRs = stream of consecutive 10B_ERR codewords

clocking options for egress client signals
Clocking Options for Egress Client Signals

STS-m

STM-n

STS-m

STM-n

8B/10B

Client

Transp.

GFP

Mapper

Framer

Transp.

GFP

De-map

8B/10B Client

Client

Source

Client

Sink

SONET / SDH

Network

  • 1.25Gb/s GbE,
  • 1.0625Gb/s FCor FICON,
  • 200Mb/s ESCON

Client Ingress

Client Transport

Client Egress

  • Egress Clock Options:
  • Recover Client clock from transportedGFP-mapped client signal; or
  • Rate adapt extracted client to locally derivedclient reference clock.
gfp overview summary
GFP Overview Summary
  • Various GFP Applications have been described and illustrated
    • Packet routing
    • Port aggregation over SONET/SDH or OTN using Linear Extension Headers
    • Resilient Packet Ring applications using Ring Extension Headers
    • Transparent Transport of 8B/10B clients
  • Basic GFP Frame Structure has been described and shown
    • Length/cHEC frame delineation, similar to ATM cell delineation.
    • Payload Headers ID encapsulated payload & encapsulation options
      • Presence or absence of optional FCS
      • Presence and type or absence of extension header
      • Payload type allows for mixing data types in a single SONET/SDH or OTN path
    • Extension headers support various network topologies
      • Null Extension Header for channelized Point-to-Point network
      • Linear Extension Header for Port Aggregation over Point-to-Point network
      • Ring Header for Resilient Packet Ring applications
  • LAN/SAN extension over WAN using Transparent Mapping described and shown
    • 64B/65B re-coding preserves data & control for “transparent” transport
    • [536,520] superblocks provide error detection / correction over relatively small blocks
    • Supports efficient transport of full-rate 8B/10B clients over smallest paths
  • Foundation laid for more easily understanding ITU-T G.7041 GFP Standard