Data centers
Which optics and switches does a single-mode university data center need?
A G.657.A2 fiber plant makes the complete optical channel central to the equipment choice.
A university cabling case reports nearly 150 server cabinets, 100G core capacity and 40G aggregation—all on a single-mode backbone and horizontal fiber plant. Here is how those requirements translate into conditional equipment choices.
The short answer
Use pluggable single-mode optics for links that traverse the structured fiber plant. Evaluate 100G CWDM4 or LR4, and 40G LR4, against the actual end-to-end channel and host support. Choose server access ports to match the NIC; reserve DAC and AOC for separate, compatible direct connections.
Single-mode campus channels connect compatible optics through documented ODF and patching paths; short-reach DAC/AOC links are a separate choice. Conceptual illustration; equipment shapes are illustrative.
Third-party supplier account · Independent analysis by SwitchInfra
Not a SwitchInfra deployment. Proposed parts are for a comparable project; installed equipment is not identified in the source.
~150 — server cabinets reported
100G — core capacity requirement
40G — horizontal / aggregation access
Single-mode — backbone & horizontal cabling
What the source actually tells us
The iCONEC account, republished by Qianjia on 10 October 2024, describes a building for animal husbandry, veterinary medicine, and nutrition and health innovation. Its machine-room works cover networking, structured cabling, video surveillance, access control, intrusion alarms, environmental monitoring and fire alarms.
The engineering constraint is the fiber plant: the supplier reports G.657.A2 single-mode preterminated cabling for both backbone and horizontal runs, with 96-fiber high-density patching. This makes the complete optical channel central to equipment selection.
iCONEC case account on Qianjia
Inside the cabinets — Transmission channels need 10G or faster; server interfaces are not specified.
Fiber termination — Panel adapters, cassettes, distances and channel losses are not disclosed.
Equipment — No installed switch or transceiver model is identified.
Future 200G–800G — A supplier capability statement, not a deployed or measured link.
How to read the analysis: capacity figures are reported requirements. The link roles below are independent examples for a similar build, rather than a reconstruction of the university’s topology.
The network, link by link
The cabling path and endpoint ports determine the options. Matching the headline speed is only the first check.
100G links across the fiber plant
Source requirement: the core area must support 100G.
Example role: a 100G connection between compatible core devices through the structured single-mode channel.
Two duplex-LC candidates are QSFP-100G-CWDM4-S and QSFP-100G-LR4-S. CWDM4 is rated to 2 km; LR4 to 10 km. Select by channel loss, both endpoint platforms, port support and the peer optic—not by buying the longest reach available.
A port-platform candidate is N9K-C93180YC-FX3: 48 × 1/10/25G SFP28 and 6 × 40/100G QSFP28 ports. Its role depends on port counts, redundancy, growth and acceptable oversubscription; this does not establish sizing for the full university room. The exact optic/software pairing remains unverified. Check applicable FEC; CWDM4 requires particular attention to the host’s FEC support and configuration. On a very short link, verify the exact module’s distance and receive-power limits. Add attenuation only if the verified budget requires it.
Cisco 100G QSFP modules data sheet · Cisco FEC summary · Cisco Nexus 9300-FX3 series data sheet
A separate short direct connection
A 3 m QSFP-100G-CU3M-RF (Cisco Refresh, remanufactured) DAC can connect compatible nearby QSFP28 ports, including adjacent cabinets where routing permits. It does not use the structured optical channel.
QSFP-100G-CWDM4-S
100G · duplex LC · up to 2 km
Conditional model inquiry
QSFP-100G-LR4-S
100G · duplex LC · up to 10 km
Conditional model inquiry
6 × 40/100G QSFP28 ports
Scale & host/optic pairing to review
These two models were not found in the targeted public catalog check. Supply remains to be confirmed.
40G aggregation over single-mode fiber
Source requirement: 40G access in the horizontal / aggregation area.
Example role: aggregation to a compatible cabinet switch. The source does not specify a 40G link to every cabinet.
QSFP-40G-LR4-S is a duplex-LC candidate with a specified operating distance of 2 m–10 km. Confirm both host ports, the supported software and the channel loss before choosing it.
A fixed-end 40G AOC provides its own complete cable path. It cannot replace a pair of pluggable optics across the existing patch panels. It remains an option for a separate compatible direct connection.
Cisco 40G QSFP modules data sheet · Cisco optics compatibility matrix
QSFP-40G-LR4-S
40G · duplex LC · 2 m–10 km
Conditional model inquiry
Match server access to the actual NIC
Source requirement: in-cabinet channels at 10G or faster.
Example decision: 10GBASE-T copper, SFP+ fiber, or a higher-rate server port. The required NIC interface and speed remain project inputs.
N3K-C3172TQ-XL-RF offers 48 × 10GBASE-T RJ45 ports and 6 × QSFP+ uplinks. Its copper access ports cannot terminate single-mode fiber. This is a conditional legacy-platform option: Cisco’s base-model security support ended in February 2025; last support is in February 2027.
For fiber-connected servers, select the optical access platform around the actual NIC rate, port count and uplink design. C9400-LC-48XS is a component of an appropriately configured Catalyst 9400 system—with C9400X-SUP-2/2XL and IOS XE 17.8.1 or later. It is not a standalone ToR switch.
Cisco Nexus 3000 hardware guide · Cisco Nexus 3172 lifecycle notice · Cisco Catalyst 9400 module installation guide
N3K-C3172TQ-XL-RF
10GBASE-T access / 40G uplink
Legacy platform; support review required
C9400-LC-48XS
48 × 1G/10G SFP/SFP+
Chassis, supervisor & software required
An MPO trunk can still end in duplex LC.
An MPO-to-LC cassette can present duplex LC at the equipment. MPO alone therefore does not decide the optical PMD, and LC is not limited to LR4 or CWDM4. Trace the entire channel before selecting the module.
CommScope MPO–LC cassette reference · Cisco 100G QSFP modules data sheet
Confirm the equipment-facing interface
Both endpoint ports, adapters, cassettes and patch cords.
Check the optical channel
Fiber characteristics, polarity, connector finish, measured loss and receive-power limits.
Then check the hosts
Exact optic PID, software, peer module and applicable FEC.
Candidate parts—and where they stop fitting
Use these roles to shortlist equipment for a comparable requirement. A catalog page establishes a listing; availability, unit condition and platform compatibility still need confirmation.
| Exact part / status | Role and selection condition |
|---|---|
| QSFP-100G-CWDM4-S Conditional candidate | 100G CWDM4 · duplex LC · up to 2 km Model inquiry only; public SwitchInfra listing and availability not verified. Cisco 100G QSFP modules data sheet |
| QSFP-100G-LR4-S Conditional candidate | 100GBASE-LR4 · duplex LC · up to 10 km Model inquiry only; public SwitchInfra listing and availability not verified. Cisco 100G QSFP modules data sheet |
| N9K-C93180YC-FX3 Conditional port platform | 48 x 1/10/25G + 6 x 40/100G 100G port-platform candidate, subject to scale, redundancy and oversubscription. Exact optic, software and FEC pairing remain unverified. Cisco Nexus 9300-FX3 series data sheet · Cisco optics compatibility matrix |
| QSFP-40G-LR4-S Conditional candidate | 40G duplex single-mode links Model inquiry only; verify both hosts and software. Cisco 40G QSFP modules data sheet · Cisco optics compatibility matrix |
| QSFP-100G-CU3M-RF (Cisco Refresh, remanufactured) Conditional direct connection | 3 m QSFP28 passive copper DAC For compatible nearby ports, including adjacent cabinets where routing permits. It does not traverse the fiber plant. Cisco 100G QSFP modules data sheet |
| N3K-C3172TQ-XL-RF Conditional legacy platform | 10GBASE-T access / 40G uplink Assess lifecycle: Cisco’s base-model security support ended February 2025; last support is February 2027. Verify support eligibility for the offered unit. Cisco Nexus 3000 hardware guide · Cisco Nexus 3172 lifecycle notice |
| C9400-LC-48XS Chassis-system component | 48-port 1G/10G line card Requires a compatible Catalyst 9400 chassis, C9400X-SUP-2/2XL and IOS XE 17.8.1 or later. It is not a standalone cabinet switch. Cisco Catalyst 9400 module installation guide |
| QSFP-H40G-AOC1M-RF QSFP-H40G-AOC3M-RF QSFP-H40G-AOC5M-RF Excluded from structured fiber path | Fixed-end direct AOC Choose an actual length SKU only for a separate direct connection. Cisco 40G QSFP modules data sheet |
| C9200L-24T-4G-E Excluded from 10G server links | 1G access and uplinks Its port rates do not meet a 10G server link requirement. Cisco Catalyst 9200 series data sheet |
The AOC entries above are actual length variants, rather than the incomplete family name “QSFP-H40G-AOC-RF”. For any -RF item, confirm the offered unit’s condition and support eligibility; the suffix alone does not establish a seller’s certification.
Continue in the relevant product family
Compare the port and platform options that serve each link role.
Network Modules and Line Cards
Discuss this project
Keep quantities open until link counts, redundancy and spares are agreed. Nearly 150 cabinets do not determine the number of optics or switches.
Follow the next selection question.
Compare related decisions while keeping each source’s scope, hardware and link conditions separate.
Browse more engineering analyses →
Expand mixed OM4 and single-mode cabling
A public Xi’an expansion account becomes a practical guide to channel allocation, 1U fiber density and patching-loss budgets.
Read the engineering analysis · Original project account
24-fiber MTP: one allocation, different optical choices
Map custom cassettes before selecting native 40G, duplex 10G or an independently proposed breakout design.
Read the engineering analysis · Original project account
Campus OS2: qualify both routes before choosing optics
Use Newcastle’s Catalyst Building account to examine per-route channel budgets and protection requirements. The installed link rates remain undisclosed.
Read the engineering analysis · Original project account
Before you finalize the links
Does single-mode fiber mean LR4 is always the right choice?
No. Select the PMD from rate, distance, loss, interfaces and host support. LR4 and CWDM4 are candidates for the links discussed here.
Can a 40G AOC use the existing patch panels?
A fixed-end AOC supplies its own complete cable path. It is not a pluggable replacement for a structured single-mode channel.
Does the existing fiber guarantee a future 400G upgrade?
No. Reassess the future optics, fiber count, connectors, channel loss and host ports. The supplier’s future-speed statement does not validate a specific upgrade.
Were these Cisco models used at the university?
The source does not identify them. They are independently assessed candidates for a comparable requirement.
Where the facts and specifications come from
- iCONEC case account on Qianjia · 10 October 2024
- University building report · 1 November 2024
- Cisco 100G QSFP modules data sheet
- Cisco 40G QSFP modules data sheet
- Cisco Nexus 9300-FX3 series data sheet
- Cisco FEC summary
- Cisco Nexus 3000 hardware guide
- Cisco Nexus 3172 lifecycle notice
- Cisco Catalyst 9400 module installation guide
- Cisco Catalyst 9200 series data sheet
- CommScope MPO–LC cassette reference
- Cisco optics compatibility matrix
Source and catalog check: 19 October 2026.
Project statements are attributed to the cabling supplier. Cisco documents support the product roles and limits; they do not establish deployment in this university project.
The university’s own building report supports building context. It does not validate the cabling configuration or optical performance.
Engineering review note.
Platform-specific engineering sign-off and the offered units’ supply, condition and support remain to be confirmed.
Related procurement context
Machine-room construction clarification · HBSJ-202101FJ-008008001 · 4 February 2024.
A separate network procurement notice, HBRS-2024047, appears in the university procurement index on 16 September 2024. These procurement-stage records do not identify the proposed Cisco parts as installed equipment.