These worked well as a typical 40Gb optical connection. But they are not compatible with Junipers virtual chassis. As soon as we enabled VCP on the port, the link would drop and stay down. Ended up having to go with OEM for these, which worked flawlessly. Support was great in trying to get it sorted out, but we ran out of time to keep testing.

Since we needed to upgrade our network, the current modules would no longer fit. These 40G QSFP+ optical transceivers were exactly what we needed. I have bought pcs of 10G SFP+ modules from FS before, which has won our trust. So I purchased these 40G modules plus with MTP cables this time without hesitation. Got some technical problems when cabling, and the account manager solved my issues timely. These 40G modules have been working perfectly in our machine room so far without any errors. No issues and no complaints. Will continue to monitor these modules' performances.

I was recommended by one friend to try modules here when I searched for 40G Cisco compatible module solutions online. I tried them on many Cisco switches and all performed well. The price was reasonable and It didn’t perform like a third-party module as I thought before. It seems that these modules will last for a long time. I’ll definitely buy some again.

I shopped some 10G modules and cables from FS before, which have been working perfectly in our data center so far. Recently, we wanted high-quality 40G optical transceivers to add some 40G links. So we purchased several Cisco QSFP-40G-SR4 compatible modules this time for our Cisco Nexus series switches. These 40G SR4 modules could split 40G to 4x10G signals, so we could reuse the modules with 10G products. Plus, we added some matched MTP patch cables including #66234 and #66240. The products are all protected well in the packages. Plug-N-play, easy to handle. No compatibility issues. These QSFP+ modules work fine so far and the 40G network is stable. I will continue to monitor the modules' performances and come back with more useful feedback then.

Haven't bought any optical products here before. Someone recommended FS.COM on Reddit. After browsing their website, we decided to buy some 40G modules for a trial. The modules worked flawlessly on our Cisco Nexus series switches and passed our tests, featuring high performance and reliability. Pretty nice! Will place a complete order for our project.

Fast service, helpful advice, good price. Thank you FS!

Ordered these as a last-minute replacement for a project, they come in on time and work great, don't seem to get hot or anything like that.

Great price and fast shipping. I tested my fiber network after installing this module and the signal was well within specs. I will be ordering from FS frequently.

These transceivers work fantastic and I've had no compatibility issues, even with multiple brands of switches and NICs. They feel very high quality and robust, run cool, and have performed well for everything I've done.

This is the second time I purchased transceivers from them, because the last 10G modules and cables I got from them worked well in the telecom room. This time, I consider to buy some 40G modules to connect two Cisco N9K-C92160YC-X in a rack, the distance is about 15m. Before I told the salesman I already got some MTP cables, she recommended using 40G QSFP+ AOC cables in my case. I have to say she is really considerate to provide more cost-saving solutions for me. She also kindly helped me place this order after I explained only these 40G modules are needed. The package comes with lots of protection for the transceivers. Worked right out of the box, just plug and play, with no compatibility issues. Till now haven't had any issues whatsoever with these modules, don't seem to get hot or anything like that. There are many more expensive transceivers out there, but these modules also work fine. No need for more expensive modules if your switch can use them.