Transcript GFP: Applications and Overview

Applications and Overview of
Generic Framing Procedure (GFP)
Mike Scholten (AMCC)
e-mail: [email protected]
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.
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What is GFP?
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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)
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Basic GFP Frame Structure
Payload Type MSB
Payload Type LSB
tHEC MSB
Length MSB
Length LSB
cHEC MSB
tHEC LSB
Ext Hdr Byte 1
Ext Hdr Byte 2
cHEC LSB
Core
Header
Payload Header
Payload
Area
Payload
Ext Hdr Byte n
eHEC MSB
eHEC LSB
Optional
Extension
Header
FCS (optional)
FCS[31:24]
FCS[23:16]
FCS[15:8]
FCS[7:0]
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Application: Packet Routing through Big Fat Pipes
Edge Switch
N x GbE
Packet
Switch
SPI-3
SPI-4
SONET
SDH
Mapper
SONET
SDH
Mapper
OC-48
STM-16
OC-192
STM-64
Router-based
WAN
• 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
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GFP Frame: PPP Packet Routing via GFP
Payload Type MSB
Payload Type LSB
tHEC MSB
Length MSB
Length LSB
cHEC MSB
tHEC LSB
cHEC LSB
Core
Header
Payload
Area
Payload Header
PPP
Packet
Payload
FCS (optional)
FCS[31:24]
FCS[23:16]
FCS[15:8]
FCS[7:0]
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Application: Port Aggregation over Digital Wrapper
Edge Switch
OTN
Mapper
N x GbE
Packet
Switch
OTU-1
DWDM
WAN
SPI-3
SPI-4
OTN
Mapper
OTU-2
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
Payload Type MSB
Payload Type LSB
tHEC MSB
Length MSB
Length LSB
Core
Header
Payload
Area
cHEC MSB
tHEC LSB
cHEC LSB
Channel ID
Payload Header
Spare
eHEC MSB
eHEC LSB
Linear
Extension
Header
Packet
Payload
FCS (optional)
FCS[31:24]
FCS[23:16]
FCS[15:8]
FCS[7:0]
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Application: Resilient Packet Rings
8B/10B
Client
OC-m
STM-n
GbE
MAC
SPI-n
Packet
Stream
HDLC
Proc.
Network
Process.
&
Switch
SPI-n
SONET
SDH
Mapper
Framer
Ring Node
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Ring
Node
Ring
Node
Packet
Ring
Ring
Node
Multiplex packet streams into single STS-Nc / VC-4-Xc
Packet Add/Drop
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
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GFP Frame: RPR Using GFP Ring Header
Payload Type MSB
Payload Type LSB
tHEC MSB
tHEC LSB
DestPort
SrcPort
Spare
Length MSB
Length LSB
cHEC MSB
cHEC LSB
Core
Header
Payload
Area
Spare
Payload Header
Ring
Extension
Header
Packet
Payload
FCS (optional)
FCS[31:24]
FCS[23:16]
NOTE: GFP Ring Header removed to Living
List; 802.17 RPR proposes to include ring
header as part of GFP payload).
FCS[15:8]
FCS[7:0]
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DE
CoS
TTL
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 MSB
eHEC LSB
T1X1.5/2002-046
Application: Extending LAN / SAN over WAN
GbE
FC
GbE
FC
LAN /
SAN
GbE
FC
8B/10B
Clients
SONET
SDH
Mapper
Framer
SONET / SDH
Network
STS-m
STM-n
STS-m
STM-n
SONET 8B/10B
Client
SDH
Mapper
Framer
SONET 8B/10B
Client
SDH
Mapper
Framer
GbE
FC
GbE
FC
• 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.
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SAN Transport through Right-Sized Pipes using VC/GFP
Nx
Fibre Chan,
GbE,
SAN - WAN PHY
FICON,
ESCON
Transparent
8B/10B
Encapsulate
Codec
/ Extract
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SONET
SDH
Mapper
with VC
OC-48/STM-16 or
OC-192/STM-64
SONET/SDH
Switched
WAN
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
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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:
Client Signal / Line Rate
Gigabit Ethernet (GbE) / 1250 Mb/s
Fibre Channel / 1062.5 Mb/s
FICON / 1062.5 Mb/s
ESCON / 200 Mb/s
VC-Path Size
STS-3c-7v / VC-4-7v
STS-3c-6v / VC-4-6v
STS-3c-6v / VC-4-6v
STS-1-4v / VC-3-4v
– 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
Input Data
SyncBit
64-bit Field
All Data
0
D1
D2
D3
D4
D5
D6
D7
D8
7 Data + 1 Control
1
0,aaa,C1
D1
D2
D3
D4
D5
D6
D7
6 Data + 2 Control
1
1,aaa,C1
0,bbb,C2
D1
D2
D3
D4
D5
D6
5 Data + 3 Control
1
1,aaa,C1
1,bbb,C2 0,ccc,C3
D1
D2
D3
D4
D5
4 Data + 4 Control
1
1,aaa,C1
1,bbb,C2 1,ccc,C3 0,ddd,C4
D1
D2
D3
D4
3 Data + 5 Control
1
1,aaa,C1
1,bbb,C2 1,ccc,C3 1,ddd,C4 0,eee,C5
D1
D2
D3
2 Data + 6 Control
1
1,aaa,C1
1,bbb,C2 1,ccc,C3 1,ddd,C4 1,eee,C5
0,fff,C6
D1
D2
1 Data + 7 Control
1
1,aaa,C1
1,bbb,C2 1,ccc,C3 1,ddd,C4 1,eee,C5
1,fff,C6
0,ggg,C7
D1
All Control
1
1,aaa,C1
1,bbb,C2 1,ccc,C3 1,ddd,C4 1,eee,C5
1,fff,C6
1,ggg,C7 0,hhh,C8
aaa = 3-bit representation of the 1st control code’s original position
bbb = 3-bit representation of the 2nd control code’s original position
…
hhh = 3-bit representation of the 8th control code’s original position
Ci = 4-bit representation of the ith control code
Di = 8-bit representation of the ith data value in order of transmission
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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
NAME
Byte Value
10B Codeword (RD-)
abcdei fghj
10B Codeword (RD+)
abcdei fghj
64B/65B
4-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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GFP Encapsulation of N x [536,520] Superblocks
Encapsulate N x [536,520] superblocks into standard GFP Frames
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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 checkbits
to form [536,520] superblock.
4. Pre-pend with GFP core & payload headers.
5. Scramble payload header & payload
with x43+1. (Core header not scrambled.)
6. Form GFP frames with N x [536,520]
superblocks.
Payload Header (4 bytes)
Core Header (4 bytes)
N x [536,520] Superblocks
Optional FCS (4 bytes)
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Handling 8B/10B Disparity
Transp. STS-m
STM-n
Client 8B/10B Client
GFP
Source • 1.25Gb/s GbE, Mapper
• 1.0625Gb/s FC Framer
SONET / SDH
Network
STS-m
STM-n Transp.
GFP
De-map
8B/10B
Client
Client
Sink
or 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 across
data packets.
• Handle received 10B_ERR.
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Signal Fail Handling in Transparent Mapping
Transp. STS-m
STM-n
Client 8B/10B Client
GFP
Source • 1.25Gb/s GbE, Mapper
• 1.0625Gb/s FC Framer
STS-m
STM-n Transp.
GFP
De-map
SONET / SDH
Network
8B/10B
Client
Client
Sink
or FICON,
• 200Mb/s ESCON
Client Ingress
Client Transport
Client Egress
Signal Fail Handling on Egress:
Signal Fail Conditions on Ingress:
• Locally detected Signal Fail
• Protocol-specific Client Signal Failures
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• Loss of Signal  GFP_CSF
• Loss of Synchronization  GFP_CSF
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
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
Transp. STS-m
STM-n
Client 8B/10B Client
GFP
Source • 1.25Gb/s GbE, Mapper
• 1.0625Gb/s FC Framer
SONET / SDH
Network
STS-m
STM-n Transp.
GFP
De-map
8B/10B
Client
Client
Sink
or FICON,
• 200Mb/s ESCON
Client Ingress
Client Transport
Client Egress
Egress Clock Options:
• Recover Client clock from transported
GFP-mapped client signal; or
• Rate adapt extracted client to locally derived
client reference clock.
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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 LOS, 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 Overview Summary
• Various GFP Applications have been described and illustrated
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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
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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
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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
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