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Ethernet over SONET

Ethernet over SONET. Dr. John S. Graham University of London Computer Centre. Ethernet vs SONET. DXC. MUX. MUX. R. R. Section Layer. Section Layer. Section Layer. Section Layer. Line Layer. Line Layer. Path Layer Connection. SONET/SDH Model. SONET Network Elements. 1. 4. 30.

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Ethernet over SONET

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  1. Ethernet over SONET Dr. John S. Graham University of London Computer Centre

  2. Ethernet vs SONET

  3. DXC MUX MUX R R Section Layer Section Layer Section Layer Section Layer Line Layer Line Layer Path Layer Connection SONET/SDH Model

  4. SONET Network Elements

  5. 1 4 30 59 90 Section SPE Path 3 PTR Line 5 86 columns SONET STS-1 Frame Payload Capacity = 756 Bytes = 48.384 Mb/s

  6. Section FramingA1 FramingA2 STS-1 ID C1 BIP-8 B1 Orderwire E1 User F1 Data Com D1 Data Com D2 Data Com D3 Section Overhead Bytes

  7. BIP-8 B2 APS K1 APS K2 Data Com D4 Data Com D5 Data Com D6 Data Com D7 Data Com D8 Data Com D9 Data Com D10 Data Com D11 Data Com D12 Line Sync Stat Z1 Line FEBE Z2 Orderwire E2 Line Overhead Bytes

  8. Path Trace J1 BIP-8 B3 Signal Label C2 Path Path Status G1 User Channel F2 Multi-frame H4 Path Overhead Bytes

  9. Accurate Bit-Level Timing • Line Coding • AMI, AMI RZ • HDB3 • Block Coding • 4B/5B (FDDI) • 5B/6B (E3) • 8B/10B (Gigabit Ethernet) • Scrambling • Frame Synchronous • Self Synchronous

  10. 8B/10B Encoding (1/2) • Ensures equal number of 1’s and 0’s for • Clock recovery • DC Balance • Detection of single bit transmission errors • Predefined ‘comma’ (0011111 and 1100000) characters

  11. 8B/10B Encoding (2/2) • Data (D) and commands (K) encoded separately • Octet split into 5 MSB and 3 LSB • Code groups generated from lookup tables D2.0

  12. Control Words (‘Ordered Sets’)

  13. Scrambling in SONET/SDH SDH STM-1 uses x7 + x6 +1 polynomial

  14. Concatenation STS-3 155 Mb/s 145.152 Mb/s STS-3c/VC-4 155 Mb/s 149.76 Mb/s STS-12 622 Mb/s580.608 Mb/s VC-4-4 622 Mb/s599 Mb/s STS-12c 622 Mb/s 599.04 Mb/s

  15. 1 A 3 - 5 ??? B F 1 – 12 (622 Mb/s) C E 7 10 -12 D 9 Provisioning Example

  16. Bandwidth Fragmentation Drop Interface (Node F) STS-3c Blocked! STS-12 Ring

  17. Virtual Concatenation Drop Interface (Node F) STS-3c STS-1-3v Ring STS-12

  18. The Magic of VCAT

  19. Differential Delay Core Network(Partial Mesh) Source STS-1-12v Sink Ty TX

  20. Multiframe Indicator

  21. 11 1 2 3 4 5 6 12 7 10 9 8 GID-a, SQ#=2 GID-a, SQ#=1 GID-b, SQ#=3 GID-b, SQ#=2 GID-a, SQ#=0 GID-b, SQ#=1 GID-a, SQ#=3 VCAT Example STS-1-4v STS-1-3v STS-12

  22. VCAT Puzzle • An STS-1-2v between Chicago and London • One STS-1 sent via geostationary satellite • The other STS-1 sent via transatlantic fibre • Will it work? ;-)

  23. VCAT: Buffer Requirements

  24. Link Capacity Adjustment Scheme • Modify membership of a VCG • On-demand and hitless bandwidth changes • Automatic removal of failed VCG members • Interworking of LCAS-enabled VCG with non-LCAS VCG • Old-style ‘bridge and roll’ requires double bandwidth

  25. LCAS Messaging • Member Status (MST) • Re-Sequence Acknowledge (RS-Ack) • Control (CTRL) • Fixed • Add • Norm • EOS • Idle • DNU • Group ID • CRC

  26. CTRL = NORM SQ = 1 CTRL = EOS SQ = 2 CTRL = IDLE SQ = 255 CTRL = NORM SQ = 1 CTRL = EOS SQ = 2 CTRL = ADD SQ = 255 CTRL = NORM SQ = 1 CTRL = EOS SQ = 2 CTRL = NORM SQ = 1 CTRL = NORM SQ = 2 CTRL = EOS SQ = 3 MST = OK (#3) CTRL = NORM SQ = 1 CTRL = NORM SQ = 2 CTRL = EOS SQ = 3 RS-ACK Source PTE STS-1 #1 STS-1 #2 STS-1 #3 LCAS Signalling Flows (1/3) MST = FAIL (#3)

  27. CTRL = NORM SQ = 1 CTRL = NORM SQ = 2 CTRL = EOS SQ = 3 CTRL = IDLE SQ = 255 CTRL = NORM SQ = 2 CTRL = EOS SQ = 3 CTRL = NORM SQ = 1 CTRL = EOS SQ = 2 MST = FAIL (#1) CTRL = NORM SQ = 1 CTRL = EOS SQ = 2 RS-ACK Source PTE STS-1 #1 STS-1 #2 STS-1 #3 LCAS Signalling Flows (2/3)

  28. CTRL = NORM SQ = 1 CTRL = NORM SQ = 2 CTRL = EOS SQ = 3 CTRL = NORM SQ = 2 CTRL = IDLE SQ = 255 CTRL = NORM SQ = 1 CTRL = EOS SQ = 2 MST = FAIL (#3) CTRL = NORM SQ = 1 CTRL = EOS SQ = 2 RS-ACK Source PTE STS-1 #1 STS-1 #2 STS-1 #3 LCAS Signalling Flows (3/3) CTRL = NORM SQ = 1

  29. Gigabit Ethernet Implementations

  30. IEEE 802.2 LLC IEEE 802.2 LLC FC-4 Upper Layer Mapping IEE 802.3 MAC IEEE 802.3 CSMA/CD FC-3 Common Services IEEE 802.3 PHY PCS FC-2 Signalling PMA FC-1 Encode/Decode PMD FC-0 Interface & Media MDL Gigabit Ethernet (802.3z) ANSI X3T11 Fibre Channel IEEE 802.3 Ethernet IEEE 802.3z Gigabit Ethernet

  31. 1000BASE-LX/SX

  32. Sequence of Events LINK_NOT_AVAILABLE ~ LINK_NOT_AVAILABLE LINK_CONFIGURATION ~ LINK_CONFIGURATION IDLE ~ IDLE SOP PREAMBLE SFD DA SA LENGTH LLC Data PADDING FCS

  33. Generic Framing Procedure • ITU-T G.7041 and ANSI T1.105.02 • Defines mapping for many types of service onto SONET/SDH or OTN: • Ethernet, IP/PPP • GbE, Fibre Channel (inc. DVB), FICON etc • Excellent bandwidth utilization; efficiency tailored to suit different client types • Simple delineation and robust error control • Extensible

  34. Motivation for GFP (1/2) • ATM • Cell overhead causes 10% bandwidth inflation • Adaptation functions needlessly complex • Packet over SONET (POS) • Requires all frames to be converted to PPP over HDLC • Byte stuffing causes non-deterministic bandwidth inflation • QoS hard to monitor or guarantee

  35. Motivation for GFP (2/2) • Minimal overhead • Transport of client PDUs in native format • Designed for optimized processing • Easy aggregation of frames from multiple client and multiple protocols into shared bandwidth channels • Low latency capabilities for SAN

  36. GFP Client Frames Control Frames Data Frames Management Frames Idle Frames OA&M Frames GFP: Types of Frame

  37. GFP: Functional Model Source = IEEE Communications Magazine, May 2002

  38. GFP: Frame Structure Source = IEEE Communications Magazine, May 2002

  39. Payload Types

  40. GFP: Client-Independent Processes • Synchronization • Bit Level • Frame Delineation • Scrambling • Multiplexing • GFP Frame • Client PDU

  41. No CHEC Match cHEC Match Hunt Presync No 2nd cHEC Match cHEC Mismatch 2nd cHEC Match Sync cHEC Match GFP: Synchronization

  42. PLI cHEC Payload PLI cHEC Payload PLI cHEC Payload PLI cHEC Payload PLI cHEC Payload PLI cHEC Payload GFP: Frame Delineation

  43. STS-3c-2v 1 1 GFP Framer GFP Framer 2 2 3 3 1 2 3 GFP: Client PDU Multiplexing Source Sink

  44. PLI (MSB) PLI (LSB) 7 cHEC (MSB 1 Preamble cHEC (LSB) 6 SFD Payload Header 6 Destination Payload 2 Source Length Data 4 FCS FCS GFP-F Encapsulation (1/2) Ethernet MAC Frame X = 4 to 64 Transmission Order 0 to 65,535 - X 4 1 8 Bit Transmission Order

  45. PLI (MSB) PLI (LSB) PPP/HDLC Frame cHEC (MSB Flag (0x7E) 1 X = 4 to 64 cHEC (LSB) Address Transmission Order 1 Payload Header Control 1 Payload 0 to 65,535 - X PPP Type 2 Data FCS 4 4 1 8 FCS Bit Transmission Order GFP-F Encapsulation (2/2)

  46. Octet Number 000 001 010 011 100 101 110 111 65B Sequence 1 1 001 C1 0 101 C2 D1 D2 D3 D4 D5 D6 GFP-T: 64B/65B Payload 64B Sequence D1 K1 D2 D3 D4 K2 D5 D6 Octet Number F 000 001 010 011 100 101 110 111

  47. GFP-T Error Detection • Leading flag bit is errored • Error affects ‘Last control-code’ indicator • Control-code location address received in error • Error causes 4-bit control code to be modified

  48. 1,1 1,2 … 1,7 1,8 1,1 8,1 1,2 8,2 … … 8,1 8,2 … 8,7 8,8 1,7 8,7 1,8 8,8 CRC (MSB) CRC (LSB) GFP-T: Superblocks 536-bit Byte-Aligned

  49. GFP-T: Bandwidth Requirements

  50. Pros and Cons: GFP-F • Higher bandwidth efficiency • Higher Latency • More buffer memory required • Core header fields must be calculated

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