I only know the basics of fiber networking but I know that different standards are needed because light refracts differently depending on cable thickness and composition, so standards/variations of the same standard have different maximum length, bandwidth, collision detection, etc.

For example, the type of fiber that you use to connect two offices that are 10 miles apart is going to be very different than the fiber you use to connect your SAN storage to your baremetal ESXI servers.

In essence, OP is asking if he can connect his phone line to the port on the back of the computer, and the answer is "Yes, but it's not that simple, and you probably don't want to do that anyways"

[–] Bazinga@lemm.ee 29 points 1 year ago (1 children)

Explained by ChatGPT:

The image shows a post from a platform or forum, likely named "Lemmy," where a user with the handle "ky56" is asking a technical question related to networking.

Here's a breakdown of the technical terms:

10GBase-LR: This refers to a specific standard of Ethernet transceiver module that can support data rates of up to 10 Gbps (Gigabits per second) and works over single-mode fiber. The "LR" in the name stands for "Long Range," indicating that this module is designed for longer distance transmissions, typically up to 10 kilometers.

QSFP-40G-LR4: "QSFP" stands for Quad Small Form-factor Pluggable. It's a compact, hot-pluggable transceiver used for data communications applications. The "40G" indicates its data rate, which is 40 Gbps. The "LR4" suggests it's designed for long-range transmissions, typically up to 10 kilometers, and it uses a 4-lane architecture.

CWDM: Stands for Coarse Wavelength Division Multiplexing. It's a technology that multiplexes multiple optical signals on a single fiber by using different wavelengths (i.e., colors) of laser light. This technique enables multiple channels to be transmitted over a single fiber, increasing the overall capacity of the communication link.

The user's question is about whether they can connect a 10GBase-LR module to a QSFP-40G-LR4 module using CWDM technology. Essentially, they're asking if it's possible to interconnect these two types of transceivers, which operate at different data rates, using a technology that allows multiple wavelengths on a single fiber.

[–] EmoDuck@sh.itjust.works 18 points 1 year ago (1 children)

Wow, that's impressive. Scary as fuck, but still impressive

[–] vrek@programming.dev 9 points 1 year ago (1 children)

Yeah but it didn't answer the question of "can you connect them?".

Others in this thread have said yes but chat gpt ignored the question and replied with a description of the question. It's easy for a model like this to determine what a model name means(it seems complicated to humans but there is a logic to their naming).

[–] Bazinga@lemm.ee 18 points 1 year ago

That's because I asked it to explain the technical aspect of the question, not answer it.

Here's the answer it gave me when I asked it to answer the question:

Yes, I can provide an answer to the technical question in the photo.

The question is: "Can I attach a 10GBase-LR to QSFP-40G-LR4 (CWDM)?"

Answer: In general, you can't directly connect a 10GBase-LR transceiver to a QSFP-40G-LR4 transceiver because they operate at different data rates (10 Gbps vs. 40 Gbps). Additionally, the QSFP-40G-LR4 typically uses four separate lanes of 10 Gbps each, which is why it has the "4" in its name.

However, there are solutions to bridge these differences:

Breakout Cables: You can use a 40G QSFP+ to 4x 10G SFP+ breakout cable. This cable will split the 40G signal from the QSFP-40G-LR4 into four separate 10G channels. You can then connect one of the 10G channels to your 10GBase-LR module. This will only utilize 10 Gbps of the 40 Gbps available from the QSFP+ port, leaving the other three channels unused.

Transponder or Media Converter: These devices can convert signals between different data rates. A transponder could take in the 10G signal from the 10GBase-LR and output it as one lane of a 40G signal compatible with the QSFP-40G-LR4. However, similar to the breakout cable, this will only utilize a fraction of the 40G capability.

Switch/Router Configuration: Some high-end networking equipment allows you to configure the data rate of specific ports. If both transceivers are plugged into such a device, you could potentially configure the QSFP-40G-LR4 port to operate at 10G, but this would be vendor and model specific.

Regarding the CWDM component, if both transceivers support CWDM and are operating on compatible wavelengths, they should be able to communicate over a CWDM system. However, CWDM is typically used to combine multiple signals onto a single fiber, so if you're just trying to connect these two transceivers, the CWDM component may not be necessary unless it's part of a larger network design.

Always consult with the documentation of your networking equipment and, if possible, conduct tests in a lab environment before making any changes to a live network.

[–] Mautobu@victoriagaming.ca 16 points 1 year ago (2 children)

This is the necessary cable. https://www.fs.com/de-en/products/30827.html

[–] nomecks@lemmy.world 7 points 1 year ago* (last edited 1 year ago) (1 children)

You can just connect a normal fiber between a 10G SFP and a 40G QSFP and let the 40G end auto negotiate to 10G. Fanout cables are better for density though.

[–] MxM111@kbin.social 2 points 1 year ago (1 children)

Does 40G QSFP transponder be able to even communicate with 10G SFP? Do they even have the same encoding? OOK? QPSK?

[–] lud@lemm.ee 3 points 1 year ago* (last edited 1 year ago)

Seems to work mostly fine: https://community.fs.com/blog/40g-qsfp-to-10g-sfp-configuration-guide.html

Considerations for QSFP+ to SFP+ Split

Usually, this split configuration is supported on most switches provided by different vendors regardless of standalone and stacked ones. Certainly, you still need to check this function in the instruction of your switch or consult your vendor, as it’s the most basic condition of splitting QSFP+ to SFP+ configuration. Sometimes, most ports on a switch support split, but some don’t. In other cases, when a switch is deployed as a leaf switch, some ports do not support the split. Or when the port is already used as a stack port, this may also limit split configuration. Thus the conditions can be quite different based on your applications.

[–] admin@sh.itjust.works 3 points 1 year ago (1 children)

Yeah they would need a breakout cable. And there’s no way in hell they can have a link of 40G via SFP+ to a 10G appliance.

[–] tjhart85@kbin.social 5 points 1 year ago (1 children)

Agreed that they can't get a 40G link when attaching to a 10G device, but the 40G QSFP can be split into 4 10G SFP+ connections instead

[–] admin@sh.itjust.works 2 points 1 year ago

Also for whoever is curious, there’s 100G QSFP28 which has breakdown cables to 4x 25G SFP28, I’m not a networks guy but I think at that point it’s not Ethernet anymore but InfiniBand.

[–] 4am@lemm.ee 11 points 1 year ago

You probably want to simplify your example to “the servers you’d connect in the same room” rather than going into “SAN” and “ESXI” or else they only people who will understand are going to be all the /r/homelab refugees in c/selfhosted, and they already all taken what this was about anyway lol