I work in research university, and we are moving to a new building. I suspect that new building will be equipped with mostly 1GbE copper, 10GbE copper, and possibly 10GbE-compatible fiber.
Is it reasonable to ask for 40GbE-compatible fiber for future-proofing?
My argument would be:
- We currently need 10GbE and they will put fiber in
- "Faster" fiber, i.e. OM4 MMF instead of OM3 MMF, is 20-30% more expensive
- But the labour cost is the major part of networking installation
- In the future we can install 40GbE switch and transceivers for small faster research VLAN linking few computers
Ask about OM4, but not for 40 Gb, for long runs of 25, 50, or 100. Price per Gb is best on 25 and 50, due to fewer lanes.
Although, fiber versus copper is a bigger difference. 25 Gb interfaces in some workstations or servers could be the right amount of bandwidth. Relatively inexpensive, until the copper to the switch closet needs to be replaced.
Certainly individual desktops/laptops are never going to see 40 GbE speeds, but there are servers. I would say you can justify routing it to data center(s) and maybe some other lightweight server "closets", but not throughout. If you are linking servers within a data center, I would cross that bridge when you need it. At this point, I would skip the copper as much as possible and just go with fiber, even to desktops. You can lower your costs that way and offset the higher speed fiber where you need it.
Yes. You definitely want to deploy the best available fiber to allow easy upgrades in the future. You should deploy OM4, OM5 or OS2 (for longer runs). Make also sure that there are enough individual strands for multi-lane PHYs, even if they are not terminated. The cost difference between different fiber grades is pretty much negligible when compared to the cost of deploying them. As John has pointed out, using PHYs with lower lane counts can also be much cheaper (single-lane 50G-BASE-SR vs. four-lane 40GBASE-SR4).
Terminating the fiber is a different thing. There likely is a large cost difference between terminating e.g. 10GBASE-SR and 40GBASE-SR4. However, which the proper fiber grade deployed you can upgrade the termination any time.
There can also be a large difference between 10GBASE-SR over MMF and 10GBASE-LR over SMF when using original SFP modules. With (much cheaper) compatible 3rd party modules, the SMF L-PHYs aren't significantly more expensive than the possibly multi-lane MMF S-PHYs.
Rule of thumb: if you want to or need to stick with original vendor SFPs, go for MMF as long as reasonably possible. If you can use 3rd party SFPs, seriously consider SMF for any deployed cable or even throughout.
Realistically planning ahead can save you a large deal of money later on without spending too much more today.