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PPT ON Generic Framing Procedure (GFP) BY

SUDANSHU GUPTA BE 7th Semester [IT]

Roll no-556/12

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CONTENTS

• What is GFP• Frame format of GFP• Modes of GFP• Types of GFP• Packet routing• Resilient Packet rings• Extending LAN/SAN over WAN• SAN Transport• Transparent GFP Mapping• Frame vs. Transparent GFP• Conclusion

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What is GFP?

• GFP is an emerging new standard for Data Encapsulation

• Accepts any client, encapsulate in simple frame, transport over network

• Uses length/HEC frame 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)

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• ITU 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. Applications are related to some of the features included in G.7041.

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• 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.

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FRAME FORMATA GFP frame consists of:• A core header• A payload header• An optional extension header• A GFP payload• An optional payload frame check sequence

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Basic GFP Frame Structure

Core Header

FCS (optional)

PayloadArea

Length MSB

Length LSB

cHEC MSB

Payload

Payload Header

FCS[31:24]

FCS[23:16]

FCS[15:8]

FCS[7:0]

Payload Type MSBPayload Type LSB

tHEC MSBtHEC LSB

OptionalExtensionHeader

cHEC LSB

eHEC MSBeHEC LSB

Ext Hdr Byte 1Ext Hdr Byte 2

Ext Hdr Byte n

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MODES OF GFP•There are two modes of GFP:-

• Generic Framing Procedure - Framed (GFP-F)

• Generic Framing Procedure - Transparent (GFP-T)

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• GFP-F maps each client frame into a single GFP frame. GFP-F is used where the client signal is framed or packetized by the client protocol.

• GFP-T on the other hand, allows mapping of multiple 8B/10B block-coded client data streams into an efficient 64B/65B block code for transport within a GFP frame.

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TYPES OF GFP There are two types of GFP frames:-

•A GFP client frame•A GFP control frame 

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• A GFP Client frame can be further classified as either a client data frame or a client management frame. The former is used to transport client data, while the latter is used to transport point-to-point management information like loss of signal, etc

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• The GFP Control frame currently consists only of a core header field with no payload area. This frame is used to compensate for the gaps between the client signal where the transport medium has a higher capacity than the client signal, and is better known as an idle frame.

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Application: Packet Routing through Big Fat Pipes

PacketSwitch

N x GbE

SONETSDH

Mapper

SONETSDH

Mapper

SPI-4

SPI-3 Router-basedWAN

OC-48STM-16

OC-192STM-64

• 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)• All packet switching in WAN is 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 is not preserved• Relies on PPP for Link Configuration

Edge Switch

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GFP Frame: PPP Packet Routing via GFP

Core Header

PayloadArea

Length MSB

Length LSB

cHEC MSB

PPPPacket

Payload

Payload Header

Payload Type MSBPayload Type LSB

tHEC MSBtHEC LSB

cHEC LSB

FCS (optional)FCS[31:24]

FCS[23:16]

FCS[15:8]

FCS[7:0]

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Application: Resilient Packet Rings

GbEMAC

OC-mSTM-n

PacketRing

HDLCProc.

SONETSDH

MapperFramer

• Resilient Packet Ring (RPR), also known as IEEE 802.17, is a protocol standard designed for the optimized transport of data traffic over optical fiber ring networks.

• Multiplex packet streams into single STS-Nc / VC-4-Xc• Each packet is encapsulated into GFP Frame• Payload Type ID in payload header supports multi-service applications.

NetworkProcess.

&Switch

SPI-nSPI-n

8B/10BClient

PacketStream

Ring Node RingNode

RingNode

RingNode

Packet Add/Drop

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GFP Frame: RPR Using GFP Ring Header

Core Header

PayloadArea

Length MSB

Length LSB

cHEC MSB

PacketPayload

Payload Header

Payload Type MSBPayload Type LSB

tHEC MSBtHEC LSB

DestPort SrcPortSpare

Spare DE CoSTTL

Dest MAC[47:40]Dest MAC[39:32]Dest MAC[31:24]Dest MAC[23:16]Dest MAC[15:8]Dest MAC[7:0]

Src MAC[47:40]Src MAC[39:32]Src MAC[31:24]Src MAC[23:16]Src MAC[15:8]Src MAC[7:0]eHEC MSBeHEC LSB

RingExtensionHeader

cHEC LSB

FCS (optional)

FCS[31:24]

FCS[23:16]

FCS[15:8]

FCS[7:0]

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

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Application: Extending LAN / SAN over WAN

GbEFC

8B/10BClients

STS-mSTM-n

8B/10BClient

STS-mSTM-n

SONET / SDHNetwork

GbEFC

GbEFC

GbEFC

LAN /SAN

8B/10BClient GbE

FC

SONETSDH

MapperFramer

SONETSDH

MapperFramer

SONETSDH

MapperFramer

• If you want to preserve individual 8B/10B block-coded channels, but cannot fit two1.25 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 we

cannot just send data packets.• Cannot just interleave two streams into single path and still expect SONET/SDH to

deliver to different destinations.

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SAN Transport through Right-Sized Pipes using GFP

N xFibre Chan,

GbE,FICON,ESCON SONET

SDHMapperwith VC

SONET/SDHSwitched

WAN

OC-48/STM-16 orOC-192/STM-64

• Transparent Encapsulation / Decapsulation preserves Control Info• Virtually-concatenated (VC) 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) is essential to compete against SAN over dark fiber

SAN - WAN PHY

8B/10BCodec

TransparentEncapsulate

/ Extract

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Transparent GFP Mapping• 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

NAME Byte Value 10B Codeword (RD-)abcdei fghj

10B Codeword (RD+)abcdei fghj

64B/65B4-bit Mapping

/K28.0/ 1C 001111 0100 110000 1011 0000

/K28.1/ 3C 001111 1001 110000 0110 0001

/K28.2/ 5C 001111 0101 110000 1010 0010

/K28.3/ 7C 001111 0011 110000 1100 0011

/K28.4/ 9C 001111 0010 110000 1101 0100

/K28.5/ BC 001111 1010 110000 0101 0101

/K28.6/ DC 001111 0110 110000 1001 0110

/K28.7/ FC 001111 1000 110000 0111 0111

/K23.7/ F7 111010 1000 000101 0111 1000

/K27.7/ FB 110110 1000 001001 0111 1001

/K29.7/ FD 101110 1000 010001 0111 1010

/K30.7/ FE 011110 1000 100001 0111 1011

10B_ERR N/A Unrecognized RD- Unrecognized RD+ 1100

65B_PAD N/A N/A N/A 1101

Spare N/A N/A N/A 1110

Spare N/A N/A N/A 1111

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Frame-Mapped GFP vs. Transparent GFP

Frame-Mapped GFP Transparent-Mapped GFP Variable Length GFP Frames Fixed Length GFP Frames 1-to-1 mapping of Data Packets to GFP Frames

N-to-1 mapping of client “characters” to GFP Frames

Point-to-Point, Packet Aggregation, or Resilient Packet Ring Network Topology

Primarily Point-to-Point Topology using Virtual Concatenation

Requires “MAC” to terminate client signal and pass only data packets.

Only 8B/10B PHY layer terminated; “MAC” not required to terminate higher layer protocol.

Data only passed in 8B format. Data and control compressed using 64B/65B re-coding.

Channel-associated control possible using GFP Control Frames.

Channel-associated control possible using GFP Control Frames.

Unclear if client Loss-of-Sync, or code violations should be communicated to far-end.

Transparent mapping defines mechanisms for communicating LOS, Loss-of-Sync, code violations to far end.

Doesn’t define client egress action due to SONET/SDH signal failure.

Defines client egress action due to SONET/SDH signal failure.

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GFP Conclusion• Various GFP Applications have been described and illustrated

– Packet routing– Port aggregation over SONET/SDH 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 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

– 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

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• LAN/SAN extension over WAN using Transparent Mapping described and shown– 64B/65B re-coding preserves data & control for

“transparent” transport– Superblocks provide error detection / correction

over relatively small blocks– Supports efficient transport of full-rate 8B/10B

clients over smallest paths.

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ANY QUESTIONS ?

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THANK YOU