What a 10G upgrade actually replaces
A rate upgrade is usually described as one job and is easier to plan as three: the ports that terminate the link, the cabling between them, and the aggregation layer that collects the traffic. Filling a SFP+ cage changes the first job and leaves the other two alone, which is why a 10G step is still the cheapest way to lift an access or campus network.
This guide covers the port side of that step. The full rate families are collected on optics selection guides, and the 10G modules themselves are listed on the 10G transceiver page.
Why 10G SFP+ is still the working access rate
The SFP+ cage is the most widely deployed 10G port in the industry, and a port that already exists costs nothing to fill. Copper and active cables cover the short runs inside a rack or across a row, while optical modules cover everything beyond them, from 300 m over multimode to 80 km over single mode. The rate is enough for a wireless access point, a camera, a small cell, or a server management and storage port.
What has changed is the uplink. A switch full of 10G access ports no longer feeds a 10G uplink, because 48 ports at 10G can fill a 100G or 400G uplink in a burst. Plan the access rate and the uplink rate as two separate decisions and the upgrade stops being a fork in the road.
Recommended modules for a 10G upgrade
| Module | Rate | Media / wavelength | Reach class | Where it usually lands |
|---|
| 10G SFP+ SR | 10G | Multimode, 850 nm | 300 m class | Within a row or a rack |
| 10G SFP+ LR | 10G | Single mode, 1310 nm | 10 km class | Building to building |
| 10G SFP+ ER | 10G | Single mode, 1310 nm | 40 km class | Campus and metro access |
| 10G SFP+ ZR | 10G | Single mode, 1550 nm | 80 km class | Extended access and rural links |
| 10G SFP+ BiDi | 10G | Single mode, duplex pair on one strand | 10 km to 40 km classes | Sites where fibre is scarce |
| 10G SFP+ CWDM and DWDM | 10G | Single mode, per channel | Per channel plan | More capacity on existing fibre |
| 10G SFP+ DAC and active cable | 10G | Copper or active fibre | Up to 100 m class | In rack and in row links |
| 25G SFP28 | 25G | Multimode or single mode | 100 m to 40 km classes | New server and uplink ports |
Reach classes are the standard ones for the family and the working limit is the measured budget of the link. The single mode options are compared on LR, ER and ZR optics and the single strand options on BiDi transceivers.
Fibre, distance and the cabling question
Multimode reach is set by the fibre grade rather than by the module. Legacy 62.5 micrometre fibre will not carry a 10G signal over the distance that OM3 or OM4 will, and the answer there is either a shorter run or single mode. Where a run sits at the edge of a multimode class, take the single mode option and stop planning around the cable.
Where fibre count is the constraint, two options avoid pulling new cable: a BiDi pair, which carries the link on one strand, and a WDM channel, which adds a link to fibre that already carries another. Both cost less than a new duct, and both need the wavelength plan written down. The passive side of that planning is described on WDM transceivers and CWDM and DWDM compared.
Port count against rate per port
There are two ways to carry more traffic: use more ports or use faster ports. More ports at 10G is the right answer where the load is spread across many devices and fibre count is not the constraint. Faster ports are the right answer where one link carries the aggregate of a rack or a row, because a single 100G link uses less fibre and less space than ten 10G links. The plan that survives is the one that keeps access ports and uplinks in separate decisions, so each can move at its own pace.
Where a site is stepping beyond 10G on the server side, the next stop is 25G SFP28 for server ports and 100G QSFP28 for uplinks, with 50G SFP56 and 40G QSFP+ covering the rows in between.
Coding, spares and the ordering inputs
Where a module goes into a switch or a router cage it is coded for the host named on the request, tested on that platform, and it is not manufactured by that brand. Coded parts for the common hosts are collected on the Cisco, HPE, Dell and Huawei pages, and the same rule applies to each of them.
Spares follow the port groups. One spare per coded group per reach class covers the usual failures, with link pairs counted together so a replacement reaches both ends. Record the wavelength and the coded record of every working part, because those two fields decide which spare can be used where.
How to choose, in order
- List the ports to be filled with rate, distance and location.
- Measure the runs and fix the fibre grade before choosing modules.
- Take the single mode option where a multimode run sits at the edge of its class.
- Decide BiDi or a WDM channel where fibre count is the constraint.
- Set the uplink rate as a separate decision from the access rate.
- Confirm the host and its release, then order one spare per coded group per reach class.
Frequently asked questions
Is 10G still worth building in a new site?
Yes for access and campus ports, where the attached devices do not exceed 10G. The uplink is where the rate decision really sits, and that can move to 100G or 400G while access stays at 10G.
Can a 10G module run on old 62.5 micrometre fibre?
Sometimes over a short run, but not to the class distance. Where the run is long or the fibre grade is unknown, use single mode rather than planning around the cable.
Do I need new cable for a 10G step?
Not usually. BiDi pairs and WDM channels add links to fibre that is already installed, which is normally cheaper than a new duct.
Should the access ports move to 25G instead?
Only where the attached devices need it. A 25G access port with a 25G uplink moves the bottleneck rather than removing it, and the usual answer is 10G access with a faster uplink.
What do you need to quote a 10G upgrade?
The port list with rate and location, the measured run lengths and fibre grade, the wavelength plan where WDM is involved, the host model and release, and the quantity per coded group with spares on a separate line.
Send the port list with measured runs, the fibre grade and the host model, and we come back with the module per port, the wavelength plan where it is needed and the spare lines set out separately. Related reading: optical communication products, BiDi and duplex links and all optics selection guides.
