Applications and Overview of Generic Framing Procedure (GFP)

1
Applications and Overview ofGeneric Framing
Procedure (GFP)

• Mike Scholten (AMCC)
• e-mail mscholten_at_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.

2
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)

3
Basic GFP Frame Structure
Optional Extension Header
FCS (optional)
4
Application Packet Routing through Big Fat Pipes
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

• 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

5
GFP Frame PPP Packet Routing via GFP
FCS (optional)
6
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
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GFP Frame Packet Aggregation over OTU-n
Linear Extension Header
FCS (optional)
8
Application Resilient Packet Rings
Ring Node
8B/10B Client
OC-m STM-n
GbE MAC
SONET SDH Mapper Framer
Network Process. Switch
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
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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).
10
Application Extending LAN / SAN over WAN
8B/10B Client
SONET / SDH Network
STS-m STM-n
SONET SDH Mapper Framer
STS-m STM-n
LAN / SAN
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, soCannot
  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
VC/GFP
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

• 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

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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

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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

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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

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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
  x431 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 x431.
(Core header not scrambled.)
6. Form GFP frames with N x 536,520superblocks.
N x 536,520 Superblocks
Payload Header (4 bytes)
Optional FCS (4 bytes)
Core Header (4 bytes)
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Handling 8B/10B Disparity
STS-m STM-n
8B/10B Client
STS-m STM-n
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.

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Signal Fail Handling in Transparent Mapping
STS-m STM-n
8B/10B Client
STS-m STM-n
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
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Clocking Options for Egress Client Signals
STS-m STM-n
8B/10B Client
STS-m STM-n
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.

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Frame-Mapped GFP vs. Transparent GFP
20
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