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what the fuck does that mean (feddit.de)

submitted 1 year ago by [email protected] to c/[email protected]

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[–] [email protected] 128 points 1 year ago (12 children)

@nx2

For the curious

10G Base LR: It's a type of fiber standard that runs a 10 gigabits. and looks like this

QSFP 40G: It's a DIFFERENT type of fiber standard that runs at 40 gigs and looks like this

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"

[–] [email protected] 16 points 1 year ago (2 children)

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

[–] [email protected] 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.

[–] [email protected] 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?

[–] [email protected] 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.

[–] [email protected] 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.

[–] [email protected] 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

[–] [email protected] 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.

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