Napatech capture SmartNICs: what actually happens with an SFP+ that is not in the qualified list
We run packet capture on a handful of Napatech cards and I am putting together the optics order for the next rack. Before spending anything I want to understand what the qualified module list actually means in practice, because the wording leaves room for interpretation.
- Napatech NT40E3 and NT20E3 capture cards in the existing hosts
- An NT200A02 going into the new build
- Mostly 10G SFP+ and 25G SFP28 links, some 40G QSFP+ towards the aggregation layer
- A shelf of Coherent FTLX8571D3BCL 10G SFP+ modules already in stock
What is on the bench:
NT40E3, NT20E3, NT200A02 - capture cards
FTLX8571D3BCL - 10G SR/LR SFP+ from stockSo far I have gone through the qualified module directory, matched a few parts against the cards we own and looked at the driver version column for each. What I still cannot work out is the failure mode. If I put a mechanically identical SFP+ that is not on that list into an NT40E3, does the card refuse it the way a switch with an EEPROM check would, or does it simply sit there dark? And on the other side of it, does being on the list actually guarantee the module gets driven?
Comments 3
No EEPROM lock on Napatech, so you can drop the switch-style rejection scenario. We have run NT20E3s and an NT40E3 for years and not once has a card spat a module out over a vendor code.
What exists instead is a directory of qualified pluggables, and it is narrower than people expect. Three things per entry: which module, which SmartNIC it was tested against, and the earliest driver release that carries it. That third one caught me out once - a part can be listed for your exact card and still do nothing under an older driver. There is a regulatory-safety column too, and it does not read the same for every entry. Your FTLX8571D3BCL turns up all over that list as a qualified 10G SR/LR part, so the shef stock is a safe start.
The catch you are asking about is written into the list itself. Listed is not the same as driven: whether a module type works depends on the firmware image - what Napatech ships in a turnkey card, or what you build yourself on a Link-Programmable one. So a mechanically fine SFP+, listed or not, can sit dark because the image never learned it, not because anything refused it. For the turnkey cards the data sheets decide, not the directory.
That is exactly the part I had wrong. I was reading the directory as a whitelist the card enforces, when it is closer to a statement of what the firmware has been taught to drive. Two of our hosts are turnkey and the new NT200A02 goes in as Link-Programmable, so those are two different questions and I will treat them that way: data sheets for the turnkey pair, our own image for the programmable card. The FTLX8571D3BCL stock covers the 10G side, and I will check the driver version column before committing to anything for the 25G links.
Worth knowing how differently vendors word this, because the practical consequence is not the same in each case.
Extreme, which now owns the Brocade SLX, VDX and MLX lines alongside its own platforms, keeps an approved list per product family. The policy note attached to it is blunt: plug in anything unapproved, optics or the interface modules that go with them, and the consequences are yours alone - they promise no warranty, make no compliance statement and take on no service obligation. Parts that are on the list carry certification to NRTL, FCC CFR 21 1040.10, CDRH, CE, EN60825-1 and/or GR-468. What it will not tell you is how a given box behaves when you insert something unlisted.
Barracuda goes the other way and keeps no appliance whitelit at all, leaning on the Intel driver test list, because acceptance is decided by the NIC: an ET076 module is 4x 10GbE SFP+ on an Intel X710, so whatever the X710 driver refuses, the firewall refuses. Cisco on the Firepower 2100 does not block non-Cisco SFPs at all, it just advises against them and TAC can decline an interoperability case involving one. Three policies, three quite different failure modes.