SFF-8636 upper pages register map (00h, 03h)

Upper memory (bytes 128–255) of a QSFP+/QSFP28 module is paged through lower byte 127. Page 00h carries the identity block that hosts validate; page 03h carries the alarm/warning thresholds and per-lane signal-integrity controls; pages 01h and 02h hold the application-select table and user EEPROM. This page lists them byte by byte and bit by bit, compiled against SFF-8636 Rev 2.11 (rev 2.10 marks later additions). Narrative: SFF-8636; runtime bytes are in the Lower page 00h map.

Legend: rsvd = reserved · vendor = vendor specific · bit 7 = MSB.

Upper page 00h — identity, bytes 128–191 (covered by CC_BASE)

Byte	Field	Contents
128	Identifier	as lower byte 0 (0Dh QSFP+, 11h QSFP28)
129	Extended identifier	7–6 power class 1–4: 00 class 1 ≤ 1.5 W · 01 class 2 ≤ 2.0 W · 10 class 3 ≤ 2.5 W · 11 class 4 ≤ 3.5 W · 5 power class 8 implemented rev 2.10 (max power in lower byte 107) · 4 CLEI code present (page 02h) · 3 CDR present in Tx · 2 CDR present in Rx · 1–0 power class 5–7: 00 not used (see 7–6) · 01 class 5 ≤ 4.0 W · 10 class 6 ≤ 4.5 W · 11 class 7 ≤ 5.0 W
130	Connector	SFF-8024 Table 4-3: 07h LC · 0Ch MPO 1×12 · 0Dh MPO 2×16 · 23h no separable connector · 27h MPO 2×12 · 28h MPO 1×16
131	Ethernet compliance	7 extended — use byte 192 · 6 10GBASE-LRM · 5 10GBASE-LR · 4 10GBASE-SR · 3 40GBASE-CR4 · 2 40GBASE-SR4 · 1 40GBASE-LR4 · 0 40G active cable (XLPPI)
132	SONET compliance	7–4 rsvd · 3 40G OTN (OTU3B/OTU3C) · 2 OC-48 long reach · 1 OC-48 intermediate · 0 OC-48 short reach
133	SAS/SATA compliance	7 SAS 24 Gb/s rev 2.10 · 6 SAS 12 Gb/s · 5 SAS 6 Gb/s · 4 SAS 3 Gb/s · 3–0 rsvd
134	Gigabit Ethernet compliance	7–4 rsvd · 3 1000BASE-T · 2 1000BASE-CX · 1 1000BASE-LX · 0 1000BASE-SX
135	FC link length / technology	7 very long (V) · 6 short (S) · 5 intermediate (I) · 4 long (L) · 3 medium (M) · 2 rsvd · 1 longwave laser (LC) · 0 electrical inter-enclosure (EL)
136	FC transmitter technology	7 electrical intra-enclosure · 6 shortwave laser w/o OFC (SN) · 5 shortwave laser with OFC (SL) · 4 longwave laser (LL) · 3–0 rsvd
137	FC transmission media	7 twin axial (TW) · 6 shielded twisted pair (TP) · 5 miniature coax (MI) · 4 video coax (TV) · 3 multimode 62.5 µm (M6) · 2 multimode 50 µm (M5) · 1 OM3 · 0 single mode (SM)
138	FC speed	7 1200 MB/s · 6 800 · 5 1600 · 4 400 · 3 3200 · 2 200 · 1 extended (SFF-8024) · 0 100 MB/s
139	Encoding	SFF-8024 Table 4-2 (QSFP column): 00h unspecified · 01h 8B/10B · 02h 4B/5B · 03h NRZ · 04h SONET scrambled · 05h 64B/66B · 06h Manchester · 07h 256B/257B · 08h PAM4
140	Nominal signalling rate	per lane, units of 100 Mb/s (67h = 10.3 Gb/s); FFh → see byte 222
141	Extended rate select compliance	7–2 rsvd · 1–0 01 = rate select version 1 (bytes 87–88 valid); 00 = not implemented
142	Length SMF	km (00h = not SMF)
143	Length OM3	units of 2 m
144	Length OM2	units of 1 m
145	Length OM1	units of 1 m
146	Length copper / OM4	copper or active cable: metres; OM4: units of 2 m (interpretation per byte 147 technology)
147	Device technology	7–4 transmitter technology: 0h 850 nm VCSEL · 1h 1310 nm VCSEL · 2h 1550 nm VCSEL · 3h 1310 nm FP · 4h 1310 nm DFB · 5h 1550 nm DFB · 6h 1310 nm EML · 7h 1550 nm EML · 8h other/undefined · 9h 1490 nm DFB · Ah copper unequalised · Bh copper passive equalised · Ch copper near & far end limiting active · Dh copper far end limiting · Eh copper near end limiting · Fh copper linear active equalisers · 3 wavelength control (1 = active) · 2 cooled transmitter · 1 detector type (1 = APD, 0 = PIN) · 0 tunable transmitter
148–163	Vendor name	16 ASCII
164	Extended module	InfiniBand: 7–5 rsvd · 4 EDR · 3 FDR · 2 QDR · 1 DDR · 0 SDR
165–167	Vendor OUI	—
168–183	Vendor PN	16 ASCII
184–185	Vendor rev	2 ASCII
186–187	Wavelength / copper attenuation	optical: wavelength in 0.05 nm units (0x6598 = 1299.2 nm) · copper: 186 attenuation at 2.5 GHz (dB), 187 at 5.0 GHz
188–189	Wavelength tolerance / attenuation	optical: ±tolerance in 0.005 nm units · copper: 188 at 7.0 GHz, 189 at 12.9 GHz
190	Max case temperature	°C (00h = 70 °C standard)
191	CC_BASE	(Σ bytes 128–190) mod 256

Upper page 00h — extended identity, bytes 192–255

Byte	Field	Contents
192	Extended specification compliance	SFF-8024 Table 4-4 (02h 100GBASE-SR4 · 03h LR4 · 06h CWDM4 · 07h PSM4 · 0Bh 100GBASE-CR4 · 11h 4×10GBASE-SR · 25h 100GBASE-DR · 40h–49h 50G/200G/400G codes …) — SFF-8024
193	Options	7 rsvd · 6 LPMode/TxDis pin function configurable rev 2.10 · 5 IntL/LOSL pin function configurable rev 2.10 · 4 Tx input EQ auto-adaptive capable · 3 Tx input EQ fixed programmable · 2 Rx output emphasis fixed programmable · 1 Rx output amplitude fixed programmable · 0 rsvd
194	Options	7 Tx CDR on/off control implemented · 6 Rx CDR on/off control implemented · 5 Tx CDR LOL flag implemented · 4 Rx CDR LOL flag implemented · 3 Rx squelch disable implemented · 2 Rx output disable capable · 1 Tx squelch disable implemented · 0 Tx squelch implemented
195	Options	7 page 02h provided · 6 page 01h provided · 5 rate select implemented · 4 Tx_Disable implemented · 3 Tx_Fault implemented · 2 Tx squelch reduces OMA (1) or Pave (0) · 1 Tx LOS implemented · 0 pages 20h–21h implemented
196–211	Vendor SN	16 ASCII
212–219	Date code	`YYMMDD` + 2 lot
220	Diagnostic monitoring type	7–4 rsvd · 3 Rx power measurement: 1 = average, 0 = OMA · 2 Tx power monitor implemented · 1–0 rsvd
221	Enhanced options	4 initialisation-complete flag implemented (lower byte 6 bit 0) · 3 rate selection declaration (0 = via byte 141 / rate select v1, 1 = via application select page 01h) · 2–0 later-revision features (TC readiness flag, software reset, Tx-disable fast mode) — check the revision
222	Extended signalling rate	per lane, units of 250 Mb/s, valid when byte 140 = FFh (67h = 25.75 Gb/s; D5h = 53.125 GBd)
223	CC_EXT	(Σ bytes 192–222) mod 256
224–255	Vendor specific	not checksummed; signatures and production data

Page 01h — application select table

Populated only when byte 195 bit 6 is set; defines applications selectable through lower bytes 89–92 / 94–97 (SFF-8079 model). Rarely implemented on QSFP28; CMIS replaced it with application descriptors.

Page 02h — user EEPROM

Bytes	Contents
128–137	CLEI code (10 ASCII) when byte 129 bit 4 is set
128–255	otherwise free user EEPROM, not checksummed

Page 03h — thresholds, bytes 128–223

Bytes	Field	Bytes	Field
128–129	Temperature high alarm	130–131	Temperature low alarm
132–133	Temperature high warning	134–135	Temperature low warning
136–143	rsvd	—	—
144–145	Vcc high alarm	146–147	Vcc low alarm
148–149	Vcc high warning	150–151	Vcc low warning
152–175	rsvd / vendor	—	—
176–177	Rx power high alarm	178–179	Rx power low alarm
180–181	Rx power high warning	182–183	Rx power low warning
184–185	Tx bias high alarm	186–187	Tx bias low alarm
188–189	Tx bias high warning	190–191	Tx bias low warning
192–193	Tx power high alarm	194–195	Tx power low alarm
196–197	Tx power high warning	198–199	Tx power low warning
200–223	rsvd	—	—

Channel thresholds apply to all four lanes; formats as the monitors (temperature 1/256 °C, Vcc 100 µV, bias 2 µA, power 0.1 µW) — Thresholds & alarms.

Page 03h — channel controls and masks, bytes 224–255

Byte	Field	Bits
224–225	vendor	—
226–233	rsvd / vendor	—
234	Tx input equalisation	7–4 Tx1 EQ level · 3–0 Tx2 EQ level (0–15, dB steps per vendor)
235	Tx input equalisation	7–4 Tx3 · 3–0 Tx4
236	Rx output emphasis	7–4 Rx1 · 3–0 Rx2
237	Rx output emphasis	7–4 Rx3 · 3–0 Rx4
238	Rx output amplitude	7–4 Rx1 · 3–0 Rx2 (codes 0–3: 100–400 / 300–600 / 400–800 / 600–1200 mVpp)
239	Rx output amplitude	7–4 Rx3 · 3–0 Rx4
240	Squelch disable	7–4 Rx4…Rx1 squelch disable · 3–0 Tx4…Tx1 squelch disable
241	Rx output disable	7–4 rsvd · 3–0 Rx4…Rx1 output disable
242	Rx power masks lanes 1–2	layout as lower byte 9
243	Rx power masks lanes 3–4	as lower byte 10
244	Tx bias masks lanes 1–2	as lower byte 11
245	Tx bias masks lanes 3–4	as lower byte 12
246	Tx power masks lanes 1–2	as lower byte 13
247	Tx power masks lanes 3–4	as lower byte 14
248–253	rsvd	—
254–255	vendor	—

Pages 20h–21h

Optional (byte 195 bit 0); rev 2.10 reserves them for extended per-lane functions and vendor use — consult the module's datasheet.

Reading a 100GBASE-SR4 identity

A typical SR4 reads: byte 128 = 11h; 129 = 00h (class 1) or 40h (class 2); 130 = 0Ch (MPO); 131 = 80h (extended); 139 = 05h (64B/66B); 140 = FFh; 222 = 67h (25.75 Gb/s per lane); 143 = 23h (70 m OM3 in 2 m units = 35); 146 = 32h (100 m OM4 / 2 = 50); 147 = 00h (850 nm VCSEL, PIN); 186–187 = 850 nm / 0.05 = 17 000 = 4268h (the exact value depends on the module's nominal wavelength field); 192 = 02h (100GBASE-SR4); 195 = 3Ch–BCh depending on the pages provided. Values differ between vendors; the point is which bytes to look at.

Lower page 00h map — flags, monitors, controls.
SFF-8472 A0h map — the SFP equivalent of the identity block.
CMIS upper pages map — the CMIS equivalent.