Cisco Optics SKU Decoder: How to Read Common Ethernet Optics Part Numbers
There is no single official Cisco SFP naming convention. Cisco’s Ethernet optics part numbers nevertheless use a recurring pattern: a product-family prefix, a speed field, a media or reach code, and sometimes a variant suffix. For example, SFP-10G-SR-S identifies a 10 Gigabit SFP+ short-reach multimode optic in Cisco’s S-Class range.
Treat that pattern as a decoder, not a formal grammar. Cisco documents each speed family separately, and the same letters can mean different things at 1G, 40G, or 400G. This guide covers the GLC, SFP, QSFP, and QDD Ethernet families most often found in enterprise BOMs. Fibre Channel, coherent DWDM, and ONS service-provider optics use other naming systems and are outside its scope.
How a Cisco Optics Part Number Is Built
Most current Ethernet optics PIDs can be read in four parts:
| Position | Field | Example values | What it tells you |
|---|---|---|---|
| 1 | Product-family prefix | GLC, SFP, QSFP, QDD | Module family and usually the associated form factor |
| 2 | Speed | 10G, 25G, 100G, 10/25G | Ethernet rate; a slash marks a dual-rate module |
| 3 | Media or reach code | T, SX, SR, LR4, DR | Media type, reach class, and sometimes lane count |
| 4 | Variant suffix | -S, -X, -I | Family-specific feature or temperature variant; absent on many PIDs |
The examples below show where the pattern works and where older GLC names depart from it:
| Part number | Decoded, field by field | What you are buying |
|---|---|---|
| GLC-TE | GLC 1G family · copper RJ-45 · EXT temperature | 1G copper SFP, up to 100 m |
| GLC-SX-MMD | GLC 1G family · SX · MM multimode · D with DOM | 1G multimode SFP, up to 1 km on supported laser-optimized MMF |
| GLC-LH-SMD | GLC 1G family · LX/LH · SM single-mode · D with DOM | 1G single-mode SFP, up to 10 km |
| SFP-10G-SR-S | SFP+ · 10G · SR · S-Class | 10G multimode, 300 m on OM3 or 400 m on OM4 |
| SFP-10/25G-LR-S | SFP28 · dual-rate 10/25G · LR · family suffix | 10 km single-mode at 10G or 25G |
| QSFP-100G-SR4-S | QSFP28 · 100G · SR4 · family suffix | 100G multimode over MPO-12, 100 m on OM4 |
| QSFP-100G-DR-S | QSFP28 · 100G · DR · family suffix | 100G single-mode over duplex LC, 500 m |
| QDD-400G-DR4-S | QSFP-DD · 400G · DR4 four 100G single-mode lanes · -S | 400G parallel single-mode, 500 m |
The GLC family predates the later structure. Its prefix implies 1G, while media and monitoring information are combined in the remaining letters. In GLC-SX-MMD and GLC-LH-SMD, MM and SM identify the fiber type and the trailing D denotes DOM. From 10G upward, the speed is normally explicit.
What the Prefix Tells You: GLC, SFP-10G, QSFP, and QDD
The prefix identifies the product family and usually indicates the form factor and speed generation:
| Prefix | Form factor | Typical rate or role |
|---|---|---|
| GLC-, SFP-GE- | SFP | 1G, usually implied by the family |
| SFP-1G- | SFP | 1G service in 10G-capable or multirate ports; not for 1G-only ports |
| SFP-10G- | SFP+ | 10G |
| SFP-25G-, SFP-10/25G- | SFP28 | 25G or dual-rate 10/25G |
| QSFP-40G- | QSFP+ | 40G |
| QSFP-100G-, QSFP-40/100- | QSFP28 | 100G or dual-rate 40/100G |
| QDD- | QSFP-DD / QSFP-DD800 | 400G and newer 800G-class products; read the rate from the rest of the PID |
| FET- | SFP+/QSFP | Nexus 2000 fabric-extender links, not general Ethernet access links |
| CVR- | Adapter | Adapts a larger port for a smaller module; it is not an optic |
Cisco’s current 1G data sheet does not expand the letters GLC. It describes the products as SFP Gigabit Interface Converters. The more important distinction is operational: SFP-1G-SX, SFP-1G-LH, and SFP-1G-T-X provide 1G connectivity but require a 10G-capable or multirate host port. They do not operate in a 1G-only SFP port.
Form-factor selection and backward compatibility are separate from PID decoding. See the SFP vs QSFP vs QSFP-DD guide when the question is which module family a new design should use.
Reach and Media Codes: SX, SR, LR, ZR, and the Lane Digits
Reach codes are family-specific. Always read them together with the speed field rather than as a standalone glossary.
1G Codes: T, SX, LX/LH, EX, ZX, and BX
The 1G family uses several legacy codes:
| Code | Medium | Max reach |
|---|---|---|
| T | Copper, RJ-45, Cat5 | 100 m |
| SX | Multimode, 850 nm | 220–550 m on legacy MMF; up to 1 km on supported laser-optimized 50 μm MMF |
| LX/LH | Single-mode, 1310 nm | 10 km (550 m on multimode with a conditioning patch cord) |
| EX | Single-mode, 1310 nm | 40 km |
| ZX | Single-mode, 1550 nm | About 70 km, depending on link budget |
| BX-D / BX-U | Single strand of single-mode fiber | 10 km per pair; BX40/BX80 variants reach 40/80 km |
GLC-LH-SMD combines the IEEE LX designation with Cisco’s LH naming. The copper PIDs GLC-T, GLC-TE, and SFP-GE-T all use RJ-45, but they also differ in temperature class, lifecycle, and in the case of SFP-GE-T, NEBS 3 ESD positioning. None reports DOM.
BX optics must be ordered as matched D/U pairs because each end transmits and receives on complementary wavelengths.
10G and 25G Codes: SR, LRM, LR, ER, ZR, and CSR
The 10G and 25G families share several codes, but their supported distances and FEC requirements are not always the same:
| Code | Medium | Max reach |
|---|---|---|
| T-X (10G) | Copper, RJ-45 | 30 m at 10G; up to 100 m at 100M/1G |
| SR | Multimode, 850 nm | 10G: 300 m OM3 / 400 m OM4; 25G: 70 m OM3 / 100 m OM4 |
| LRM (10G) | Legacy multimode, 1310 nm | 220 m on supported legacy MMF |
| LR | Single-mode, 1310 nm | 10 km; 25G operation requires host FEC on relevant PIDs |
| ER | Single-mode, 1550 nm | 40 km; 25G operation requires host FEC |
| ZR (10G) | Single-mode, 1550 nm | About 80 km, subject to link budget and attenuation requirements |
| SL (25G) | Multimode, 850 nm | 20 m OM3 / 30 m OM4 |
| CSR (10/25G) | Multimode, 850 nm | Up to 300 m OM3 / 400 m OM4; full 25G reach requires RS-FEC |
The slash in SFP-10/25G-LR-S belongs to the speed field and identifies a dual-rate module. It does not remove the need to check host FEC requirements at 25G.
For fiber-plant and cost selection rather than PID syntax, see the SFP-10G-LR vs SFP-10G-SR guide.
40G to 400G Codes: SR4, DR, FR, LR4, CWDM4, and ZR4
At 40G and above, a digit often identifies the number of optical lanes or wavelengths. It does not by itself identify the connector.
| Code | Medium | Max reach |
|---|---|---|
| SR4 | Parallel multimode, MPO | 40G: 100 m OM3 / 150 m OM4; 100G: 70 m OM3 / 100 m OM4 |
| CSR4 (40G) | Parallel multimode, MPO | 300 m on OM3, 400 m on OM4 |
| BD, SR-BD, SR1.2, SR4.2 | Wavelength-multiplexed duplex multimode | Usually 70–150 m, depending on PID and fiber |
| VR4 (400G) | Parallel multimode, MPO-12 | 30 m OM3 / 50 m OM4 or OM5 |
| SR8 (400G) | Parallel multimode, MPO-16 | 70 m OM3 / 100 m OM4 |
| PSM4 (100G) | Parallel single-mode, MPO | 500 m |
| DR (100G) | Single-wavelength single-mode, duplex LC | 500 m |
| DR4 (400G) | Four parallel single-mode lanes, MPO | 500 m |
| FR / FR4 | Single-mode, single-wavelength or four-wavelength design | 2 km |
| LR / LR4 / LR8 | Single-mode | 10 km |
| CWDM4 (100G) | Single-mode, four muxed wavelengths | 2 km |
| ERL / ER4L | Single-mode, ER-Lite | 25 km / 40 km with host FEC |
| ZR4 (100G) | Single-mode, four muxed wavelengths | About 80 km, subject to the fiber link budget |
The connector still depends on the complete code. QSFP-100G-DR-S is a single-wavelength duplex-LC optic, while QDD-400G-DR4-S uses four parallel lanes and MPO. Reading only DR would miss that difference.
Why the Same Letters Mean Different Things at Different Speeds
The same letters can describe different properties in different families:
- DR: GLC-GE-DR-LX uses DR for dual rate (100M/1G). QSFP-100G-DR-S and QDD-400G-DR4-S use DR for the 500 m single-mode reach class.
- CSR at 40G: QSFP-40G-CSR4 is a parallel-MPO optic. QSFP-40G-CSR-S uses duplex LC and four internal wavelengths.
- SR: supported distance falls as the lane rate increases. The 10G OM3/OM4 figures must not be reused for 25G or 100G.
- Legacy PIDs: WSP-Q40GLR4L is a 2 km 40G LR4-Lite module whose prefix does not follow the current QSFP pattern.
When a PID does not fit the family table, use the exact product data sheet rather than inferring its meaning from a nearby model.
Variant Suffixes: What -S, -X, -I, and D Mean in Each Family
Suffixes are also family-specific. A meaning documented for a 10G module should not be applied automatically to a 100G or 400G PID.
| Suffix | Documented meaning | Applies to | Watch for |
|---|---|---|---|
| -S | S-Class on 10G and selected 40G base/-S pairs | SFP-10G-SR-S, SFP-10G-LR-S, QSFP-40G-SR4-S | 10G S-Class optics do not support FCoE; QSFP-40G-SR4-S also lacks 4x10G breakout. Later families require PID-specific review. |
| -X | Multirate optical variant at extended temperature on documented 10G families | SFP-10G-SR-X, SFP-10G-LR-X | Do not assume every PID ending in X has the same protocol set. SFP-10G-T-X and SFP-1G-T-X are copper products with their own definitions. |
| -I | Industrial-temperature variant | Selected 10G, 25G, and 100G families | Multirate and CPRI support vary by exact PID. IND temperature does not qualify the rest of the link for outdoor use. |
| Trailing D (no hyphen) | “with DOM”: the module reports optical power, temperature, and bias telemetry | 1G GLC media blocks: MMD, SMD | This is part of the media field, not a dash suffix |
| -RGD | Rugged build, industrial temperature | 1G: GLC-T-RGD, GLC-SX-MM-RGD | |
| -D / -U (BiDi) | Downstream / upstream wavelength assignment | Selected BX families | Order as a matched pair |
For the 1G and 10G families, Cisco defines commercial (COM) as 0 to 70°C, extended (EXT) as -5 to 85°C, and industrial (IND) as -40 to 85°C.
When both a base PID and an -S PID exist, compare three items before ordering: temperature range, supported features, and platform/software compatibility. For example, QSFP-40G-SR4 supports 4x10G breakout; QSFP-40G-SR4-S does not.
DAC and AOC Part Numbers: CU, ACU, and Breakout Codes
Cable PIDs add a length field. In SFP-H10GB-CU3M, SFP-H10GB identifies the 10G SFP+ host interface, CU means passive copper, and 3M means three meters.
| Segment | Meaning | Examples |
|---|---|---|
| CU + length | Passive copper Twinax | SFP-H10GB-CU3M, QSFP-H40G-CU5M, QDD-400-CU2M |
| ACU / AC + length | Active copper, for the longer runs | SFP-H10GB-ACU10M, QSFP-4X10G-AC7M |
| AOC + length | Active optical cable | SFP-25G-AOC5M, QSFP-100G-AOC15M |
| 4SFP10G / 4SFP25G | Breakout: far end splits into four SFP-class connectors | QSFP-4SFP10G-CU3M, QSFP-4SFP25G-CU2M |
| 4ZQ100 / 2Q200 | 400G breakout: four 100G or two 200G QSFP56 far ends | QDD-4ZQ100-CU2M, QDD-2Q200-CU3M |
For 25G passive DACs, length also affects host configuration. Cisco specifies no FEC for 1, 1.5, and 2 m cables; BASE-R FEC for 2.5 and 3 m; and RS-FEC for 4 and 5 m. The length therefore belongs in the compatibility check, not only in the cable-management plan.
What a Cisco Optics SKU Does Not Tell You
The PID describes the module. It does not establish that the module is supported, current, or appropriate for a particular design.
| Question | Encoded in the PID? | Where to verify |
|---|---|---|
| Does the target switch or line card support it? | No | Cisco optics compatibility matrix, including the minimum software release |
| Does a base/-S pair have the same features? | No | Exact family data sheet and product row |
| Is the module current, end-of-sale, or replaced? | No | Current Cisco EOL/EOS notice and replacement table |
| Will a third-party-coded optic be accepted and supported? | No | Platform software policy and vendor support terms |
If a port has already rejected or err-disabled a non-Cisco module, use the unsupported transceiver error guide for platform-specific checks and recovery steps.
How to Verify Compatibility in the Cisco Optics Matrix
Check each BOM line in the Cisco Optics-to-Device Compatibility Matrix:
- Search by the switch or line-card PID to list supported transceivers, or search by the optic PID to list supported devices.
- Confirm the exact device/optic combination rather than a product family alone.
- Check the minimum software release and compare it with the installed release.
- Use the companion interoperability matrix when the two ends use different module families or generations.
If the exact combination is absent, treat it as unconfirmed rather than assuming that a mechanically compatible module will work.
FAQ
Does the -S in a Cisco optics PID mean single-mode? No. In the 10G family, -S identifies an S-Class variant; the fiber type comes from the reach code. SFP-10G-SR-S is multimode, while SFP-10G-LR-S is single-mode. For other speed families, check the exact PID rather than assigning a universal meaning to -S.
Can SFP-10G-SR and SFP-10G-SR-S operate on opposite ends of the same link? Yes. Cisco lists them with the same 10GBASE-SR optical specifications. Their differences concern the supported feature set, not the SR optical interface. Platform compatibility still needs to be checked at both ends.
Do Cisco optics part numbers encode the connector type? Not as a separate field. The complete media code often indicates the connector, but a partial code can mislead. QSFP-100G-DR-S uses duplex LC, while QDD-400G-DR4-S uses MPO. Confirm the connector in the exact data-sheet row before ordering patch leads or trunks.
What does the = sign after a part number mean? An equals sign identifies the spare-orderable version of the PID. For example, GLC-TE= is the standalone spare form of GLC-TE; it does not indicate a different optical or electrical specification.
PID decoding is the first check, not the last. For an ambiguous BOM, review the Cisco optics range or send us the PID list with the target platform and software release so the exact variant, compatibility, and availability can be checked before ordering.
