How to wire two offices on two separate floors together

The company I work for is expanding to a new office on the same building but one floor below. I wondering how best to connect the two network together in order to have one single network.

Upstairs we have all internal servers (NAS, domain, etc) and the endpoint for the Internet connection. Downstairs there will only be desktop clients. Ideally clients of both offices would share the same access to servers and Internet. The switches are HP v1910 on both offices. There will be around 15 users active per office, at peak times.

If I run a cable between the two switches, that would be around 70 meters long. Unfortunately the cable will have to pass near electricity cables.

Could I achieve decent performance with a couple of cat6 cables? Is it worth to invest on fibre cables?

Solution 1:

Cat6 wil give you 100 meter. 55 meter is the rating for using 10 Gb/s which your switches can't do anyway.
But if you are worried about electrical interference (Cat6 is pretty resilient but you never know) fiber is certainly a fairly cheap option.

All ProCurve 1910 models have at least 1 SFP port into which you can place a HP 1 Gb/s SFP transceiver (HP X121, J4858C).
This is the cheapest fiber module and will give you a minimum of 300 meters (possible more depending on type of fiber cable). Check the HP website for compatible fiber-types but for this sort of distance you can use just about any type of fiber.
No need to install an multi-strand fiber-cable with patch-panels at each end (which can get pretty expensive).
Just buy a couple of long ready-made patch-cables with LC connectors at both ends and run these through the cable ducts. Make sure they are loose in the ducts. Don't stress (pull) on the cables while laying it. And don't make sharp bends.
That's all there is to it. You can basically treat those fiber-links as just another 1 Gb/s UTP connection in the switch-configurations.

Solution 2:

Given the distance and proximity to power cables, yes, fiber makes sense. The maximum length of a Cat6 run is 55 meters for it to be within spec. I would simply buy two switches, each with a GBIC uplink port. Install a fiber module in each and you should be good to go. It's not all that expensive.