What would be the best way to connect from a "fiber optic only" switch to a regular copper rj45 switch? Which of the configurations shown in the attached diagram would work properly? Should I go for a "regular" switch that has a dedicated sfp[+] port or use a media converter in between the two? My preferred fiber optic switch would be this one. Also, can I put a second router as shown and put it into a different subnet and still have internet access behind it?

enter image description here

  • 1
    Why are you using a 10G aggregation switch in such a small environment? That seems like massive overkill. – Evan Anderson Nov 11 '14 at 20:14
  • Thanks for your answer, I am not actually already using it, I am planning to implement it because it will be in a building that's currently being planned and doesn't even exist yet. We want to use that opportunity and run fiber optic right from the beginning so we can save lots of money and future-proof a wee bit and upgrade to 10g when we need it. In the beginning we will use 1000sx fiber anyway. – pming Nov 11 '14 at 20:18
  • 2
    @pming if you have the budget and want to spend it, then all well and good. However you may be over-capitalising. I've only built two 10Gb networks and they were both built for political point-scoring, and had little real-life practicality. Your budget may be better spent making substantial savings on the switching gear and buying better WiFi gear and end-use computers. Or perhaps a better internet uplink. I'm yet to see an office installation of that size that even approaches the limits of a 1Gb backbone. But hey, it's your budget. – Mark Henderson Nov 11 '14 at 20:31
  • 3
    If you want to future proof, make it really easy to run cable around the building instead. If you're connecting between buildings then by all means use fibre and media converters if required. I personally think you're wasting your money here. – Matt Nov 11 '14 at 20:42

This is a greenfield site? Honestly, I wouldn't use that switch.

10G is an annoying beast, because the SFP+ specifications do not specify enough power to run RJ45 transceivers, so you have a lot of fibre options, or direct SFP+ to SFP+ copper.

However, there are switches on the market that have a mix of SFP+ and 10GbE RJ45 connections. For example, the Dell N4032 switch has 24 SFP+ ports, as well as two 40Gb ports, and each 40GB port can be broken out into 4x 10Gb RJ45 ports.

Another option would be to get that full SFP+ switch, and then use SFP+ to SFP+ connections to trunk that switch into another fully copper switch. Or if the other switches are a fair way away, you could use fibre transeivers instead. For example, the Dell N2048 has 48x 1Gb RJ45 and two SFP+ ports so that you could trunk 20Gbps of bandwidth from that switch into your 10Gbps switch.

The other option, although it defeats the purpose of having a 10Gb switch, would just to be use a 1Gb transceivers on both switches.

  • Thank you for both your answers. As I said I will be using 1000sx (1gb) for the first couple of months and upgrade to 10gbase-sr later. I'll probably get that 10g switch at first anyway because I want to make it as comfortable as possible for me so I will only need to switch the transceivers when I want to upgrade to 10gbase-sr. And using the "trunk" method which you have stated sounds very good, also because I won't have to exchange the media converters once I upgrade. – pming Nov 11 '14 at 20:52

It's not a "fibre optic only" switch. It's a SFP+ cage switch.

You can get 1GBase-T SFP modules (BTW, 10GBase-T SFP+ modules do not exist) for the 10Gb switch then use regular CAT5 to hook them together.

Or better, get a 1Gb switch with SFP+ cages for 10Gb uplinks and use DACs to hook them together.

  • Thanks for your answer. Of course I was referring to an sfp+ cage switch, I'm sorry that was a bit unclear. Also, I think "10GBASE-SR" is the correct term for what I am trying to say (10 gigabit ethernet on a fiber optic cable). The Problem with DACs is really that they're extremely expensive and they don't really exist in the size I need them to be, for example one of the copper switches will be about 20 meters or further away from the first switch. – pming Nov 11 '14 at 20:31
  • DACs (copper or optical) are a heck of a lot cheaper than SFP+ LC optics! OK, so for your use case you'll only be hooking up 1Gb, use a 1GBase-T module. But seriously, look at whether you really need 10Gb. – MikeyB Nov 11 '14 at 20:47
  • The only places I can get these wires from sell DACs not longer than 7 Meters and they cost around 800 $ each, while 20 Meter SC-SC MMF cables cost 90 $. Can you put a link where they sell 15+ Meter DACs that cost the same or less than OM3 fiber cables? – pming Nov 11 '14 at 20:59
  • @pming DACs have a very limited length because of the amount of power available, combined with the attenuation of the cable. Most twinax can only go to 5m, but I have heard of cables with tighter tolerances up to 10m. But they are really meant for in-rack switching, or stacking to the next rack across, not really trunking to switches in other rooms. Plus the connectors are large and tough to get through physical conduits and trunking holes. – Mark Henderson Nov 11 '14 at 21:29

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.