Progress and Challenges toward 100Gbps Ethernet

Progress and Challenges toward 100Gbps Ethernet
Joel Goergen VP of Technology / Chief Scientist Abstract: This technical presentation will focus on the progress and challenges for development of technology and standards for 100 GbE. Joel is an active contributor to IEEE802.3 and the Optical Internetworking Forum (OIF) standards process. Joel will discuss design methodology, enabling technologies, emerging specifications, and crucial considerations for performance and reliability for this next iteration of LAN/WAN technology.

Overview Network Standards Today Available Technology Today
Feasible Technology for 2009 The Push for Standards within IEEE and OIF Anatomy of a 100Gbps or 160Gbps Solution Summary Backup Slides

Network Standards Today: The Basic Evolution
2010??? 100 GbE ??? 2002 10 GbE 1996 1 GbE Look at history Ethernet has gone in steps of 10 100 GbE is the next logical Ethernet step BUT you must emphasize Force10 is a standards-based compnay We have voting rights and participation on both the IETF and IEEE We will follow ANY standard that is developed 1994 100Mb 1983 10 Mb

Network Standards Today: The Basic Structure

Network Standards Today: The Desk top
1Gbps Ethernet 10/100/1000 Copper ports have been shipping with most desktop and laptop machines for a few years. Fiber SMF/MMF IEEE a/b/g Wireless Average useable bandwidth reaching 50Mbps

Network Standards Today: Clusters and Servers
1Gbps Ethernet Copper 10Gbps Ethernet Fiber CX-4

Network Standards Today: Coming Soon
10Gbps LRM Multi-mode fiber to 220meters. 10Gbps Base-T 100meters at more then 10Watts per port ??? 30meters short reach at 3Watts per port ??? 10Gbps Back Plane 1Gbps, 4x3.125Gbps, 1x10Gbps over 1meter improved fr-4 material.

Available Technology Today: System Implementation A+B
Front End Line Card 1G A 1G SPIx B Front End Line Card 10G 10G A SPIx 1G 1G B Passive Copper Backplane A Fabric A B Fabric B

Available Technology Today: System Implementation N+1
Front End Line Card 1G SPIx 1G L1 Front End Line Card 10G 10G SPIx Ln+1 1G 1G Passive Copper Backplane 1st Switch Fabric L1 Ln Ln+1 Nth Switch Fabric N+1 Switch Fabric

Available Technology Today: Zoom to Front-end
Line Card 1G SPIx 1G L1 Front End Line Card 10G 10G SPIx Ln+1 1G 1G Passive Copper Backplane 1st Switch Fabric L1 Ln Ln+1 Nth Switch Fabric N+1 Switch Fabric

Available Technology Today: Front-end
Copper RJ45 RJ21 (mini … carries 6 ports) Fiber XFP and variants (10Gbps) SFP and variants (1Gbps) XENPAK LC/SC bulkhead for WAN modules

Available Technology Today: Front-end System Interfaces
TBI 10bit Interface. Max speed 3.125Gbps. SPI-4 / SXI System Protocol Interface. 16bit Interface. Max speed 11Gbps. SPI-5 System Protocol Interface. 16bit Interface. Max speed 50Gbps. XFI 10Gbps Serial Interface.

Available Technology Today: Front-end Pipe Diameter
1Gbps 1Gbps doesn’t handle a lot of data anymore. Non standard parallel also available based on OIF VSR. 10Gbps LAN/WAN or OC-192 As port density increases, using 10Gbps as an upstream pipe will no longer be effective. 40Gbps OC-768 Not effective port density in an asynchronous system. Optics cost close to 30times 10Gbps Ethernet.

Available Technology Today: Front-end Distance Requirements
x00 m (MMF) SONET/SDH (Parallel): OIF VSR-4, VSR-5 Ethernet:: 10GBASE-SR, 10GBASE-LX4, 10GBASE-LRM 2-10 km SONET/SDH: OC-192/STM-64 SR-1/I-64.1, OC-768/STM-256 VSR2000-3R2/etc. Ethernet: 10GBASE-LR ~40 km SONET/SDH: OC-192/STM-64 IR-2/S-64.2, OC-768/STM-256 Ethernet: 10GBASE-ER ~100 km SONET/SDH: OC-192/STM-64 LR-2/L-64.2, OC-768/STM-256 Ethernet: 10GBASE-ZR DWDM OTN: ITU G.709 OTU-2, OTU-3 Assertion Each of these applications must be solved for ultra high data rate interfaces.

Available Technology Today: Increasing Pipe Diameter
1Gbps LAN by 10links parallel 10Gbps LAN by x-links WDM 10Gbps LAN by x physical links Multiple OC-192 or OC-768 Channels

Available Technology Today: Zoom to Back Plane
Front End Line Card 1G SPIx 1G L1 Front End Line Card 10G 10G SPIx Ln+1 1G 1G Passive Copper Backplane 1st Switch Fabric L1 Ln Ln+1 Nth Switch Fabric N+1 Switch Fabric

Available Technology Today: Back Plane
Data Packet Line Cards --GbE / 10 GbE RPMs SFMs Power Supplies SERDES Backplane Traces

Available Technology Today: Making a Back Plane
Simple! It’s just multiple sheets of glass with copper traces and copper planes added for electrical connections. Reference: Isola

Available Technology Today: Back Plane Pipe Diameter
1.25Gbps Used in systems with five to ten year old technology. 2.5Gbps/3.125Gbps Used in systems with five year old or less technology. 5Gbps/6.25Gbps Used within the last 12 months.

Available Technology Today: Increasing Pipe Diameter
Can’t WDM copper 10.3Gbps/12.5Gbps Not largely deployed at this time. Increasing the pipe diameter on a back plane with assigned slot pins can only be done by changing the glass construction.

Available Technology Today: Pipe Diameter is NOT Flexible
Once the pipe is designed and built to a certain pipe speed, making the pipe faster is extremely difficult, if not impossible.

Available Technology Today: Gbits Density per Slot with Front End and Back Plane Interfaces Combined
Year System Introduced Slot density 2000 40Gbps 2004 60Gbps 2006/7 – in design now 120Gbps Based on max back plane thickness of 300mils, 20TX and 20RX differential pipes.

Feasible Technology for 2009: Defining the Next Generation
The overall network architecture for next generation ultra high (100, 120 and 160Gbps) data rate interfaces should be similar in concept to the successful network architecture deployed today using 10Gbps and 40Gbps interfaces. The internal node architectures for ultra high (100, 120 and 160Gbps) data rate interfaces should follow similar concepts in use for 10Gbps and 40Gbps interfaces. All new concepts need to be examined, but there are major advantages to scaling current methods with new technology.

Feasible Technology for 2009: Front-end Pipe Diameter
80Gbps … not enough Return On Investment 100Gbps 120Gbps 160Gbps Reasonable Channel Widths 10λ by Gbps 8λ by Gbps 4λ by Gbps 1λ by Gbps Suggest starting at an achievable channel width while pursuing a timeline to optimize the width in terms of density, power, feasibility, and cost - depending on optical interface application/reach.

Feasible Technology for 2009: Front-end Distance Requirements
x00 m (MMF) SONET/SDH: OC-3072/STM-1024 VSR Ethernet: 100GBASE-S 2-10 km SONET/SDH: OC-3072/STM-1024 SR Ethernet: 100GBASE-L ~40 km SONET/SDH: OC-3072/STM-1024 IR-2 Ethernet: 100GBASE-E ~100 km SONET/SDH: OC-3072/STM-1024 LR-2 Ethernet: 100GBASE-Z DWDM (OTN) SONET/SDH: Mapping of OC-3072/STM-1024 Ethernet: Mapping of 100GBASE Assertion These optical interfaces are defined today at the lower speeds. It is highly likely that industry will want these same interface specifications for the ultra high speeds. Optical interfaces, with exception of VSR, are not typically defined in OIF. In order to specify the system level electrical interfaces, some idea of what industry will do with the optical interface has to be discussed. It is not the intent of this presentation to launch these optical interface efforts within OIF.

Feasible Technology for 2009: Front-end System Interfaces
Reasonable Channel Widths (SPI-?) 16 lane by Gbps 10 lane by 10-16Gbps 8 lane by Gbps 5 lane by 20-32Gbps 4 lane by 25-40Gbps Port Density is impacted by channel width. Fewer lanes translates to higher Port Density and less power.

Feasible Technology for 2009: Back Plane Pipe Diameter
Reasonable Channel Widths 16 lane by Gbps 10 lane by10-16Gbps 8 lane by Gbps 5 lane by 20-32Gbps 4 lane by 25-40Gbps Port Density is impacted by channel width. Fewer lanes translates to higher Port Density and less power.

Feasible Technology for 2009: Pipe Diameter is NOT Flexible
New Back Plane designs will have to have pipes that can handle 20Gbps to 25Gbps.

Feasible Technology for 2009: Gbits Density per Slot with Front End and Back Plane Interfaces Combined Year System Introduced Slot density 2000 40Gbps 2004 60Gbps 2006/7 – in design now 120Gbps 2009 500Gbps Based on max back plane thickness of 300mils, 20TX and 20RX differential pipes.

Feasible Technology for 2009: 100Gbps Options
Bit rate shown above is based on 100Gbps. Scale the bit rate accordingly to achieve 160Gbps.

The Push for Standards: Interplay Between the OIF & IEEE
OIF defines multi-source agreements within the Telecom Industry. Optics and EDC for LAN/WAN SERDES definition Channel models and simulation tools IEEE 802 covers LAN/MAN Ethernet 802.1 and define Ethernet over copper cables, fiber cables, and back planes. 802.3 leverages efforts from OIF. Membership in both bodies is important for developing next generation standards.

The Push for Standards: OIF
Force10 Labs introduced three efforts within OIF to drive 100Gbps to 160Gbps connectivity. Two interfaces for interconnecting optics, ASICs, and backplanes. A 25Gbps SERDES Updates of design criteria to the Systems User Group

Case Study: Standards Process P802.3ah – Nov 2000 / Sept 2004
Call for Interest By a member of 802.3 50% WG vote Study Group Open participation 75% WG PAR vote, 50% EC & Stds Bd Task Force Open participation 75% WG vote Working Group Ballot Members of 802.3 75% WG ballot, EC approval Sponsor Ballot Public ballot group Let’s look at the process KEY TAKEAWAYS It takes three years for the IEEE to finalize a standard As we will see in later slides, it takes over 3 years for a technology to have sufficient selling volume for pricing to be seen as attractive by the mass market Conclusion! Either 40 or 100 GbE are 6 to 10 years away from being adopted by the mainstream market 75% of ballot group Standards Board Approval RevCom & Stds Board 50% vote Publication IEEE Staff, project leaders

Case Study: Standards Process 10GBASE_LRM: 2003 / 2006
Optical Power Budget (OMA) 10GBASE-LRM Innovations: TWDP Software reference equalizer Determines EDC penalty of transmitter Dual Launch Centre and MCP Maximum coverage for minimum EDC penalty Stress Channels Precursor, split and post-cursor Canonical tests for EDC Launch power (min) - 4.5 dBm 0.5 dB: Transmitter implementation 0.4 dB: Fiber attenuation 0.3 dB: RIN 0.2 dB: Modal noise 4.4 dB: TP3 TWDP and connector 99% confidence level 0.9 dB: Unallocated power dBm Required effective receiver sensitivity Nov03 CFI Jan04 Study Group May04 Taskforce Nov03 TF Ballot Mar05 WG BAllot Dec05 Sponsor Ballot Mid-06 Standard Time line Reference: David Cunningham – Avago Technologies

Case Study: Standards Process 10GBASE_LRM
Specified optical power levels (OMA) Optical input to receiver (TP3) compliance test allocation Power budget starting at TP2 Launch power minimum - 4.5dBm Transmit implementation allowance = 0.5 dB Connector losses = 1.5dB Attenuation (2 dB) Fiber attenuation = 0.4 dB Fiber attenuation = 0.4dB Modal noise = 0.2 dB Interaction penalty = 0.1dB - 6.5 dBm Stressed receiver sensitivity Modal noise = 0.2 dB RIN = 0.3 dB Noise (0.5 dB) RIN = 0.3 dB Ideal EDC power penalty, PIE_D = 4.2dB TWDP and connector loss at 99th percentile (4.4 dB) Dispersion (4.2 dB) Unallocated margin 0.9 dB dBm Effective maximum unstressed 10GBASE-LRM receiver sensitivity Reference: David Cunningham – Avago Technologies

Case Study: Standards Process 10GBASE_T: 2002 / 2006
Techno-babble 64B/65B encoding (similar to 10GBASE-R) LDPC(1723,2048) framing DSQ128 constellation mapping (PAM16 with ½ the code points removed) Tomlinson-Harshima precoder Reach Cat 6 up to 55 m with the caveat of meeting TIA TSB-155 Cat 6A up to 100 m Cat 7 up to 100 m Cat 5 and 5e are not specified Power Estimates for worst case range from 10 to 15 W Short reach mode (30 m) has a target of sub 4 W

Case Study: Standards Process 10GBASE_T
Noise and EMI Alien crosstalk has the biggest impact on UTP cabling Screened and/or shielded cabling has better performance Power Strong preference for copper technologies, even though higher power Short reach and better performance cable reduce power requirement Timeline The standard is coming… products in the market end of `06, early `07 Tutorial & CFI PAR Task Force review 802.3 Ballot Sponsor Ballot NOV 2002 MAR 2003 JUL NOV MAR 2004 JUL NOV MAR 2005 JUL NOV MAR 2006 JUL 1st Technical Presentation D1.0 D2.0 D3.0 STD

Birth of A Standard It Takes About 5 Years
Ideas from industry Feasibility and research Call for Interest (CFI) –100 GbE EFFORT IS HERE Marketing / Sales potential, technical feasibility Study Group Work Group Drafts Final member vote

The Push for Standards: IEEE
Force10 introduces a Call for Interest (CFI) in July 2006 IEEE802 with Tyco Electronics. Meetings will be held in the coming months to determine the CFI and the efforts required. We target July 2006 because of resources within IEEE. Joel Goergen and John D’Ambrosia will chair the CFI effort. The anchor team is composed of key contributors from Force10, Tyco, Intel, Quake, and Cisco. It has since broadened to include over 30 companies.

The Ethernet Alliance Promoting All Ethernet IEEE Work
Key IEEE 802 Ethernet projects include 100 GbE Backplane 10 GbE LRM / MMF 10 G Base-T Force10 is on the BoD, principle member 20 companies at launch Sun, Intel, Foundry, Broadcam. . . Now approaching 40 companies Launch January 10, 2006 Opportunity for customers to speak on behalf of 100 GbE Ethernet

Anatomy of a 100Gbps Solution: Architectural Disclaimers
There Are Many Ways to Implement a system This section covers two basic types. Issues facing 100Gbps ports are addressed in basic form. Channel Performance or ‘Pipe Capacity’ is difficult to measure Two Popular Chassis Heights 24in to 34in Height (2 or 3 Per Rack) 10in to 14in Height (5 to 8 Per Rack)

Anatomy of a 100Gbps Solution: What is a SERDES?
Device that attaches to the ‘channel’ or ‘pipe’ Transmitter: Parallel to serial Tap values Pre-emphasis Receiver: Serial to Parallel Clock and Data Recovery DFE Circuits are very sensitive to power noise and low Signal to Noise Ration (SNR) Reference: Altera

Anatomy of a 100Gbps Solution: Interfaces that use SERDES
TBI 10bit Interface. Max speed 3.125Gbps across all 10 lanes. This is a parallel interface that does not use SERDES technology. SPI-4 / SXI System Protocol Interface. 16bit Interface. Max speed 11Gbps. This is a parallel interface that does not use SERDES technology. SPI-5 System Protocol Interface. 16bit Interface. Max speed 50Gbps. This uses 16 SERDES interfaces at speeds up to 3.125Gbps. XFI 10Gbps Serial Interface. This uses 1 SERDES at Gbps. XAUI 10Gbps 4 lane Interface. This uses 4 SERDES devices at 3.125Gbps each.

Anatomy of a 100Gbps Solution: Power Noise thought …
Line Card SERDES Noise Limits Analog target 60mVpp ripple Digital target 150mVpp ripple Fabric SERDES Noise Limits Analog target 30mVpp ripple Digital target 100mVpp ripple 100Gbps interfaces won’t operate well if these limits can not be meet.

Anatomy of a 100Gbps Solution: Memory Selection
Advanced Content-Addressable Memory (CAM) Goal: Less power per search Goal: 4 times more performance Goal: Enhanced flexible table management schemes Memories Replacing SRAMs with DRAMs when performance allows to conserve cost Quad Data Rate III SRAMs for speed SERDES based DRAMs for buffer memory Need to drive JEDEC for serial memories that can be easily implemented in a communication system. The industry is going to have to work harder to get high speed memories for Network Processing in order to reduce latency. Memory chips are usually the last thought! This will need to change for 100Gbps sustained performance.

Anatomy of a 100Gbps Solution: ASIC Selection
High Speed Interfaces Interfaces to MACs, Backplane, Buffer Memory are all SERDES based. SERDES all the way. Higher gate counts with internal memories target to 6.25 SERDES; higher speeds difficult to design in this environment. SERDES used to replace parallel busing for reduced pin and gate count Smaller Process Geometry Definitely 0.09 micron or lower More gates(100% more gates over 0.13 micron process) Better performance(25% better performance) Lower power(1/2 the 0.13 micron process power) Use power optimized libraries Hierarchical Placement and Layout of the Chips Flat placement is no longer a viable option To achieve cost control, ASIC SERDES speed is limited to 6.25Gbps in high density applications.

Anatomy of a 100Gbps Solution: N+1 Redundant Fabric - BP
Front End Line Card SPIx L1 Front End Line Card SPIx Ln+1 Passive Copper Backplane 1st Switch Fabric L1 Ln Ln+1 Nth Switch Fabric N+1 Switch Fabric

Anatomy of a 100Gbps Solution: N+1 Redundant Fabric – MP
Passive Copper Midplane Line Card Front End L1 SPIx SPIx Line Card Front End Ln+1 SPIx SPIx 1st Switch Fabric L1 Ln Ln+1 Nth Switch Fabric N+1 Switch Fabric

Anatomy of a 100Gbps Solution: N+1 High Speed Channel Routing
Line Card Line Card Line Card Line Card 1st Switch Fabric 2nd Switch Fabric Nth Switch Fabric N+1 Switch Fabric

Anatomy of a 100Gbps Solution: A/B Redundant Fabric - BP
Front End Line Card A SPIx B Front End Line Card A SPIx B Passive Copper Backplane A Fabric A B Fabric B

Anatomy of a 100Gbps Solution: A/B Redundant Fabric – MP
Passive Copper Midplane Line Card Front End A SPIx SPIx B Line Card Front End A SPIx SPIx B A Fabric A B Fabric B

Anatomy of a 100Gbps Solution: A/B High Speed Channel Routing
Switch Fabric B Switch Fabric Line Card Line Card Line Card Line Card

Anatomy of a 100Gbps Solution: A Quick Thought …..
Looking at both Routing and Connector Complexity designed into the differential signaling …. Best Case: N+1 Fabric in a Back Plane. Worst Case: A/B Fabric in a Mid Plane. All implementations need to be examined for best possible performance over all deployed network interfaces. Manufacturability and channel (Pipe) noise are two of the bigger factors.

Anatomy of a 100Gbps Solution: Determine Trace Lengths
After careful review of possible Line Card, Switch Fabric, and Back Plane Architectural blocks, determine the range of trace lengths that exist between a SERDES transmitter and a SERDES receiver. 30 inches or .75meters total should do it. Several factors stem from trace length. Band Width Reflections from via and or thru-holes Circuit board material BER Coding Keep in mind that the goal is to target one or both basic chassis dimensions.

Anatomy of a 100Gbps Solution: Channel Model Description
A “Channel” or “Pipe” is a high speed single-ended or differential signal connecting the SERDES transmitter to the SERDES receiver. The context of “Channel” or “Pipe” from this point is considered differential. Develop a channel model based on the implications of Architectural choices and trace lengths. Identifies a clean launch route to a BGA device. Identifies design constraints and concerns. Includes practical recommendations. Identifies channel Bandwidth.

Anatomy of a 100Gbps Solution: Channel Simulation Model
TP5 Informative TP1 TP2 and TP3 not used TP4 XMTR CONN PLUG CONN JACK CONN JACK CONN PLUG DC block RCV FILTER RCV SLICER FR4+ FR4+ FR4+ FR4+ Transmitter Channel equivalent cap circuit Receiver Back Plane Line Card: Receiver

Anatomy of a 100Gbps Solution: Channel: Back Plane
Shows signal trace connecting pins on separate connectors across a back plane.

Anatomy of a 100Gbps Solution: Channel: Line Card Receiver
Shows a signal trace connecting the back plane to a SERDES in a Ball Grid Array (BGA) package.

Channel Model Definition: Back Plane Band Width
How do we Evaluate the signal speed that can be placed on a channel? 2Ghz to 3Ghz Band Width Supports 2.5Gps NRZ – 8B10B 2Ghz to 4Ghz Band Width Supports 3.125Gps NRZ – 8B10B 2Ghz to 5Ghz Band Width (4Ghz low FEXT) Supports 6.25Gps PAM4 Supports 3.125Gps NRZ – 8B10B or Scrambling 2Ghz to 6.5Ghz Supports 6.25Gps NRZ – 8B10B Limited Scrambling Algorithms 2Ghz to 7.5Ghz Supports 12Gps 2Ghz to 9Ghz Supports 25Ghz multi-level

Channel Model Definition – IEEE 802.3ae XAUI Limit
b1 = 6.5e-6 b2 = 2.0e-10 b3 = 3.30e-20 SDD21 = -20*log10(e)*(b1*sqrt(f) + b2*f + b3*f^2) f = 50Mhz to 15000Mhz

Channel Model Definition – IEEE 802.3ap A(min)
b1 = 2.25e-5 b2 = 1.20e-10 b3 = 3.50e-20 b4 = 1.25e-30 SDD21 = -20*log10(e)*(b1*sqrt(f) + b2*f + b3*f^2 - b4*f^3) f = 50Mhz to 15000Mhz

Anatomy of a 100Gbps Solution: Channel Model Limit Lines

Anatomy of a 100Gbps Solution: Comments on Limit Lines
IEEE802.3ae XAUI is a 5year old channel model limit line. IEEE P802.3ap channel model limit is based on mathematical representation of improved FR-4 material properties and closely matches “real life” channels. This type of modeling will be essential for 100Gbps interfaces. A real channel is shown with typical design violations common in the days of XAUI. Attention to specific design techniques in the channel launch conditions can eliminate the violation to the defined channel limits.

Anatomy of a 100Gbps Solution: Receiver Conditions – Case 1
TP5 Informative TP4 trace trace trace dogbone 12mil 24mil 24milx32mil 24milx32mil 24mil 24mil 6 21mil BGA AG 13mil Drill 13mil Drill 13mil Drill 24mil 24mil 24mil trace to BP trace 34mil Anti Pad

Anatomy of a 100Gbps Solution: Constraints & Concerns – Case 1
Poor Signal Integrity – SDD11/22/21 Standard Cad Approach Easiest / Lowest Cost to Implement Approach will not have the required performance for SERDES implementations used in 100Gbps interfaces.

Anatomy of a 100Gbps Solution: Receiver Conditions– Case 4
TP5 Informative TP4 trace trace trace dogbone 12mil 24mil 24milx32mil 24milx32mil 6 21mil BGA AG 13mil Drill 24mil trace to BP 34mil Anti Pad

Ideal Signal Integrity Eliminates two VIAS Increases pad impedance to reduce SDD11/22 High speed BGA pins must reside on the outer pin rows Crosstalk to traces routed under the open ground pad is an issue for both the BGA and the Capacitor footprint Requires 50mil pitch BGA packaging to avoid ground plane isolation on the ground layer under the BGA pads Potential to require additional routing layer

Available Technology Today: Remember this Slide ?
Circuit board material is just multiple sheets of glass with copper traces and copper planes added for electrical connections. Reference: Isola

Anatomy of a 100Gbps Solution: Channel Design Considerations
Circuit Board Material Selection is Based on the Following: Temperature and Humidity effects on Df (Dissipation Factor) and Dk (Dielectric Constant) Required mounting holes for mother-card mounting, shock and vibration Required number of times a chip or connector can be replaced Required number of times a pin can be replaced on a back plane Aspect ratio (Drilled hole size to board thickness) Power plane copper weight Coding / Signaling scheme

Anatomy of a 100Gbps Solution: Materials in Perspective
Graph provided by Zhi Wong

“Improved FR-4” in Reference to IEEE P802.3ap
Improved FR-4 (Mid Resolution Signal Integrity): 100Mhz: Dk ≤ 3.60; Df ≤ .0092 1Ghz: Dk ≤ 3.60; Df ≤ .0092 2Ghz: Dk ≤ 3.50; Df ≤ .0115 5Ghz: Dk ≤ 3.50; Df ≤ .0115 10Ghz: Dk ≤ 3.40; Df ≤ .0125 20Ghz: Dk ≤ 3.20; Df ≤ .0140 Temperature and Humidity Tolerance (0-55degC, 10-90% non-condensing): Dk:+/- .04 Df: +/- .001 Resin Tolerance (standard +/-2%): Dk:+/- .02 Df: +/

Anatomy of a 100Gbps Solution: Channel or Pipe Considerations
Channel Constraints Include the Following: Return Loss Thru-hole reflections Routing reflections Insertion Loss based on material category Insertion Loss based on length to first reflection point Define coding and baud rate based on material category Connector hole crosstalk Trace to trace crosstalk DC blocking Capacitor at the SERDES to avoid shorting DC between cards. Temperature and Humidity losses/expectations based on material category

Channel Model Starting Point: Materials in Perspective
Target Area Graph provided by Zhi Wong

Channel Model Starting Point: Real Channels

Channel Model Starting Point: Equation
b1 = 1.25e-5 b2 = 1.20e-10 b3 = 2.50e-20 b4 = 0.95e-30 SDD21 = -20*log10(e)*(b1*sqrt(f) + b2*f + b3*f^2 - b4*f^3) f = 50Mhz to 15000Mhz

Channel BER Data transmitted across the back plane channel is usually done in a frame with header and payload The frame size can be anywhere from a few hundred bytes to 16Kbytes, typical A typical frame contains many PHY-layer packets BER of 10E-12 will result in a frame error of 10E-7 or less, depending on distribution That is a lot of frame loss

Channel BER Customers want to see a frame loss of zero Systems architects want to see a frame loss of zero Zero error is difficult to test and verify … none of us will live that long The BER goal should be 10E-15 It can be tested and verified at the system design level Simulate to 10E-17 Any frame loss beyond that will have minimal effect on current packet handling/processing algorithms Current SERDES do not support this. Effective 10E-15 is obtained by both power noise control and channel model loss This will be tough to get through, but without this tight requirement, 100Gbps interfaces will need to run faster by 3% to 7%. Or worse, pay a latency penalty for using FEC or DFE.

Anatomy of a 100Gbps Solution: Remember Interface Speeds …
Reasonable Channel Widths for 100Gbps: 16 lane by 6.25Gbps *BEST 10 lane by 10Gbps 8 lane by 12.5Gbps 5 lane by 20Gbps 4 lane by 25Gbps *BEST

Anatomy of a 100Gbps Solution: Channel Signaling Thoughts
NRZ In general, breaks down after 12.5Gbps 8B10B is not going to work at 25Gbps 64B66B is not going to work at 25Gbps Scrambling is not going to work at 25Gbps Duo-Binary Demonstrated to 33Gbps PAM4 or PAMx

Anatomy of a 100Gbps Solution: Designing for EMI Compatibility
Treat each slot as a unique chamber Shielding Effectiveness determines the maximum number of 1GigE ports, 10GigE ports, or 100GigE ports before saturating emissions requirements. Requires top and bottom seal using honeycomb Seal the back plane / mid plane Cross-hatch chassis ground Chassis ground edge guard and not edge plate Digital ground sandwich for all signal layers Provide carrier mating surface EMI follows wave equations. Signaling spectrum must be considered.

Anatomy of a 100Gbps Solution: Power Design
Power Routing Architecture from Inputs to All Cards Bus bar Power board Cabling harness Distribution through the back plane / mid plane using copper foil Design the Input Filter for Maximum Insertion Loss and Return Loss Protects your own equipment Protects all equipment on the power circuit Design Current Flow Paths for 15DegC Max Rise, 5 DegC Typical Design all Distribution Thru-holes to Support 200% Loading at 60DegC Provides for the case when the incorrect drill size is selected in the drilling machine and escapes computer comparison. Unlikely case but required in carrier applications Power Follows Ohm’s Law. It Can Not Be Increased without Major Changes or Serious Thermal Concerns

Summary Industry has been successful scaling speed since 10Mbps in 1983. The efforts in 1GigE and 10GigE have taught us many aspects of interfaces and interface technology. 100Gbps and 160Gbps success will depend on useable chip and optics interfaces. Significant effort is underway in both IEEE and OIF to define and invent interface to support the next generation speeds. Systems designers will need to address many new issues to support 100Gbps port densities of 56 or more per box.

Thank You

Backup Slides The following slides provide additional detail to support information provided within the base presentation.

Acronym Cheat Sheet CDR – Clock and Data Recovery
CEI – Common Electrical Interface CGND / DGND – Chassis Ground / Digital Ground EDC – Electronic Dispersion Compensation MAC – Media Access Control MDNEXT / MDFEXT – Multi Disturber Near / Far End Cross Talk MSA – Multi Source Agreement NEXT / FEXT – Near / Far End Cross Talk OIF – Optical Internetworking Forum PLL - Physical Link Layer SERDES – Serialize / De-serialize SFI – System Framer Interface SMF / MMF – Single Mode Fiber / Multi Mode Fiber XAUI – 10Gig Attachment Unit Interface

Anatomy of a 100Gbps Solution: Basic Line Card Architecture
PHY, Framer Network Processor Fabric Interface PMD Non “Wire Speed” µP Protocol Stacks, Applications APPs

Anatomy of a 100Gbps Solution: Basic Line Card Architecture 1
Media Forwarding Engine Backplane Optical or Copper Reserved for Power Network Processor SERDES Architecture: Long trace lengths. Poor power noise control means worse than... Analog target 60mVpp ripple Digital target 150mVpp ripple Poor SERDES to connector signal flow will maximize ground noise. This layout is not a good choice for 100Gbps.

Media Forwarding Engine Backplane Optical or Copper Reserved for Power Network Processor S E R D Architecture: Clean trace routing. Good power noise control means better than... Analog target 60mVpp ripple Digital target 150mVpp ripple Excellent SERDES to connector signal flow to minimize ground noise. Best choice for 100Gbps systems.

Midplane Media Forwarding Engine Optical or Copper Reserved for Power Network Processor S E R D Architecture: Clean trace routing. Good power noise control means better than... Analog target 60mVpp ripple Digital target 150mVpp ripple Difficult SERDES to connector signal flow because of Mid Plane. This layout is not a good choice for 100Gbps.

Anatomy of a 100Gbps Solution: Basic Switch Fabric Architecture
Digital or Analog X bar Line Card Interface Line Card Interface Non “Wire Speed” µP

Anatomy of a 100Gbps Solution: Basic Switch Fabric Architecture 1
Reserved for Power Digital Cross Bar SERDES Architecture: Long trace lengths. Poor power noise control means worse than... Analog target 30mVpp ripple Digital target 100mVpp ripple Poor SERDES to connector signal flow will maximize ground noise. This layout is not a good choice for 100Gbps.

Digital Cross Bar S E R D Reserved for Power Architecture: Clean trace routing. Good power noise control means better than... Analog target 30mVpp ripple Digital target 100mVpp ripple Excellent SERDES to connector signal flow to minimize ground noise.

Analog Cross Bar Reserved for Power Architecture: Clean trace routing. Good power noise control means better than... Analog target 30mVpp ripple Digital target 100mVpp ripple Excellent SERDES to connector signal flow to minimize ground noise. True Analog Fabric is not used anymore.

Anatomy of a 100Gbps Solution: Back Plane or Mid Plane
Redundancy N+1 Fabric A / B Fabric Connections Back Plane Mid Plane

Anatomy of a 100Gbps Solution: Trace Length Combinations - Max
24in to 34in height (2 or 3 per rack)

Anatomy of a 100Gbps Solution: Trace Length Combinations - Min
24in to 34in height (2 or 3 per rack)

Anatomy of a 100Gbps Solution: Trace Length Combinations - Max
10in to 14in height (5 to 8 per rack)

Anatomy of a 100Gbps Solution: Trace Length Combinations - Min
10in to 14in height (5 to 8 per rack)

Crosstalk to Traces Routed Under the Open Ground Pad is an Issue Allows Good Pin Escape from the BGA Poor Signal Integrity - Has High SDD11/22/21 at the BGA Potential to Require Additional Routing Layer Approach will not have the required performance for SERDES implementations used in 100Gbps interfaces.

Allows for Inner High Speed Pad Usage within the BGA Medium Poor Signal Integrity – SDD11/22/21. Has the Extra VIAS to Content with in the Break Out Increases pad impedance to reduce SDD11/22 Crosstalk to Traces Routed Under the Open Ground Pad is an Issue for Both the BGA and the Capacitor Footprint Allows Good Pin Escape from the BGA Potential to Require Additional Routing Layer Requires 50mil Pitch BGA Packaging to Avoid Ground Plane Isolation on the Ground Layer Under the BGA Pads

Anatomy of a 100Gbps Solution: Stack-up Detail

Requirements to Consider when Increasing Channel Speed
Signaling Scheme vs Available Bandwidth NEXT/FEXT Margins Average Power Noise as Seen by the Receive Slicing Circuit and the PLL Insertion Loss (SDD21) Limits

Progress and Challenges toward 100Gbps Ethernet

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Progress and Challenges toward 100Gbps Ethernet

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