Let's get PHYsical - Speaker Deck

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Let’s get PHYsical The Switch Hacker’s Guide to Ethernet PHYs and SFPs

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Switch / MAC 1G PHY 1G PHY 10G PHY 10G PHY RJ45 SFP RJ45 SFP+ 40G PHY QSFP+

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Ethernet 101

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MAC 0101010101 PHY

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Terminology SPEEDBASE-MEDIA 10BASE-T 40GBASE-SR4

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Unshielded Twisted Pair Media 10BASE-T 100BASE-TX 1000BASE-T 2500BASE-T 5GBASE-T 10GBASE-T

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Fiber Optic Media 1000BASE-SX 1000BASE-LX 10GBASE-SR 10GBASE-LR 10GBASE-LRM 40GBASE-SR4 40GBASE-LR4 40GBASE-SR-BiDi

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Shielded Copper Media 10GSFP+Cu 40GBASE-CR4

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Duplexity

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Simplex Half-Duplex Full-Duplex

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Simplex (usually) Half-Duplex Full-Duplex (these days)

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1000BASE-T

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T/F Full-Duplex is optional

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Auto-Negotiation

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10BASE-T Link Integrity Test Pulse

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Fast Link Pulse Bursts

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Fast Link Pulse Burst Detail Clock pulses Data pulses

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Base Page

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T/F Auto-Negotiation is optional

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T/F No Auto-Negotiation for fiber

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Interfaces

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Switch / MAC 1G PHY 1G PHY 10G PHY 10G PHY RJ45 SFP RJ45 SFP+ 40G PHY QSFP+ Media Dependent Interface

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“MDI”

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MDI / MDI-X

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Differential Signaling

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Switch / MAC 1G PHY 1G PHY 10G PHY 10G PHY RJ45 SFP RJ45 SFP+ 40G PHY QSFP+ Media Independent Interface QSGMII XFI XLAUI

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MII

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RMII

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GMII

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RGMII

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SGMII

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QSGMII

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Switch / MAC 1G PHY 1G PHY 10G PHY 10G PHY RJ45 SFP RJ45 SFP+ 40G PHY QSFP+ Internal & External PHYs PHY PHY PHY PHY PHY

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PHYnally...

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Switch / MAC 1G PHY 1G PHY 10G PHY 10G PHY RJ45 SFP RJ45 SFP+ 40G PHY QSFP+ La raison d’etre

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Physical Coding Sublayer (PCS)

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Block Coding Overhead Block Code Overhead Line Rate 100BASE-TX 4B/5B 25% 125 Mbaud 1000BASE-X 8B/10B 25% 1250 Mbaud 10GBASE-R 64B/66B 3.125% 10.3125 Gbaud

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Physical Medium Attachment sublayer

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Physical Medium Dependent sublayer

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PHY management

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Clause 22

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Clause 45

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Registers

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1.c848.13 Device Register Bit

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Pluggables

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SFP / SFP+

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XFI / SFI

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QSFP+

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XLAUI / XLPPI

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# i2cget -y 12 0x53 27 w 0x8890 # i2cget -y 13 0x56 27 w 0x8480 Managing the SFP’s Internal PHY

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Switch / MAC 1G PHY 1G PHY 10G PHY 10G PHY RJ45 SFP RJ45 SFP+ 40G PHY QSFP+ It’s PHYs All the Way Down PHY PHY PHY PHY PHY PHY

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But wait, that’s not all!

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PoE

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EEE

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Backplane Ethernet

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25GBASE-T 40GBASE-T

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Recommended Reading Ethernet: The Definitive Guide -- Available on Safari Books Online (free for us!) 10GE Pluggable Transceiver Technology -- Great background on SFP+ modules The Packet Sniffer Blog -- Explains 10G Ethernet; interesting article on switch latency 40 Gigabit Ethernet and 100 Gigabit Ethernet Technology Overview -- Introduction to 40G and 100G Ethernet Overview of the XAUI, XLAUI and CAUI -- Explains the 10G, 40G, and 100G media-independent interfaces Demystifying 40 Gigabit Ethernet Physical Layer Interfaces in Data Centers -- Compares XFI/SFI and XLAUI/XLPPI The Network Sherpa -- Blog covering signal equalization, pre-emphasis, differential signalling, ASIC design An introduction to the Auto-Negotiation process -- Expansive coverage of Clause 28 twisted-pair Auto-Negotiation 1000BASE-T SFP Auto-Negotiation -- Detailed study of how Clause 28 and Clause 37 AN are used in 1000BASE-T SFPs

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Thanks!

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Back-up

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Ethernet over Twisted Pair Copper 10BASE-T 802.3i 1990 100 m Cat-3 100BASE-TX 802.3u 1995 100 m Cat-5 1000BASE-T 802.3ab 1999 100 m Cat-5 2.5GBASE-T 802.3bz 2016 100 m Cat-5e 5GBASE-T 802.3bz 2016 100 m Cat-5e 10GBASE-T 802.3an 2006 55 m Cat-6 100 m Cat-6a

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1000BASE-SX 802.3z 1998 550 m OM3 1000BASE-LX 802.3z 1998 10 km SMF 10GBASE-SR 802.3ae 2002 300 m OM3 10GBASE-LR 802.3ae 2002 10 km SMF 10GBASE-LRM 802.3aq 2006 220 m MMF 40GBASE-SR4 802.3ba 2010 100 m OM3 4 lanes 40GBASE-LR4 802.3ba 2010 10 km SMF 4 λs 40GBASE-SR-BiDi Cisco 2013 100 m OM3 2 λs Ethernet over Optical Fiber

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10GSFP+Cu SFF-8431 2009 7m twinax SFP+ 40GBASE-CR4 802.3ba 2010 7m twinax QSFP+ Ethernet over Shielded Twin-axial Copper

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10GBASE-KR 802.3ap 2007 40GBASE-KR4 802.3ba 2010 Backplane Ethernet

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Media Independent Interface (MII) Connector

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AUI 10 Mbps 1-bit MII 10/100 Mbps 4-bit GMII 10/100/1000 Mbps 8-bit XGMII 10 Gbps 32-bit XLGMII 40 Gbps 64-bit Media Independent Interfaces MAC PHY

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SGMII 10/100/1000 Mbps QSGMII 10/100/1000 Mbps x 4 XAUI 10 Gbps USXGMII 100M/1G/2.5G/5G/10Gbps XLAUI 40 Gbps Serial Media Independent Interfaces MAC PHY

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Clause 28: Parallel Detection If an interface configured for AN receives valid signalling from link partner, it will assume half-duplex at the detected speed. 1000BASE-X does not support parallel detection: if one link partner has AN enabled and the other does not, the link will not come up.

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SFP Bit Rate Bit rate specified in hundreds of megabit, rounded: 13 == 1300 Mbps =~ 1.250 Gbps == 1000BASE-X 103 == 10300 Mbps =~ 10.3125 Gbps == 10GBASE-R