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I'm thinking on building my own (micro-atx) router for business and personal projects at home.

My question is what kind of network card do I need to receive the fiber optic connection? I'm currently using the router my ISP provides me but I want to replace it.

I've been looking and I can only find super expensive cards (more than 150-250€) and I think those are not the ones I need, so can anyone point me in the right direction?

I will be using a Linux distro with iptables, dhcp, bind, etc...

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    Obvious question: what's the current router provided? (make and model). Might help us clear up some of the confusion. Is it actually fiber optic to the device, lots of UK ISPs sell "fiber" connections that are FTTC with a VDSL downlink. Much cheaper consumer routers. – pjc50 Feb 14 '17 at 10:11
  • The router is a ZTE F680 (ISP: Jazztel Spain). Unless VDSL can go through a fiber optics cable, I think it's legit fiber, the connector is SC type, what I don't know if it's multi or single mode (neither the upstream/downstream channels). If you didn't read it in a comment below, I can actually see the word PON engraved on the router case surface where the SC port is. But I read a 2 yo article saying that Jazztel moved from GPON to 10Gb PON. – Chazy Chaz Feb 14 '17 at 12:58
  • I can see in the router page, a tab named PON Status with info about ONU state (o5), i/o power, temperature, voltage, bias... But that's irrelevant. – Chazy Chaz Feb 14 '17 at 13:08
  • If the original retail price at balticnetworks.com/… is accurate ($1500!), it's not really surprising that you're finding it expensive to replicate. – pjc50 Feb 14 '17 at 13:20
  • Well, $1500 yet security sucks... All it took was a symlink in a usb drive to open it. I definitely want to run my own (up-to-date) software. So it's GPON, how do I look for a compatible module? Looking for: ITU-T G.984.x / G.988 GPON standards and Class B+ optical module, Class 1 Laser? – Chazy Chaz Feb 14 '17 at 13:39
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You don't want to buy a "fiber card". What you want is a card (or preferably a switch) that has either SFP or SFP+ ports.

This will allow you to purchase cheap optics depending on what you need, and will ensure that you're future-proof if you need to upgrade or change optics in the future.

As for what type of optics you'll need, that's a conversation you will need to have with your ISP. Whatever you have will need to match whatever is on the other end of your fiber pair.

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    As an aside, FS is a great reasonably-priced outlet for purchasing optics. – EEAA Feb 13 '17 at 21:45
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    No, read the answer. The point of getting an SFP card is that you can swap out optics if needed. If you switch ISPs and the new one needs different optics, you switch that out and the card stays the same. – EEAA Feb 13 '17 at 22:11
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    No, I mean the SFP module that goes into the SFP slot on your card. Research this stuff a bit, it's not complicated. :) – EEAA Feb 13 '17 at 22:16
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    FWIW, a switch is not what you want for a WAN connection. Switches do not have feature sets optimized for WAN. Please consider recommending a router (which I took the liberty of editing into your answer) – Mike Pennington Feb 14 '17 at 0:33
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    @MikePennington The OP wants to build a router. I'm well aware that a router must be involved, but in this case I really did mean to recommend a switch (which would more or less function as a media converter in this case). – EEAA Feb 14 '17 at 0:44
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You need to find out what standard your ISP is using before you can start shopping for hardware to connect to it.

IF it's a fiber ethernet variant then you can use a network card with a SFP/SFP+ slot (SFP is for 1 gigabit, SFP+ for 10 gigabit) and a suitable transciever module.

If it's GPON then internal interface cards for PCs don't seem to exist, it seems you have to buy a seperate "GPON modem".

If it is some legacy telco standard you will need different hardware again.

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  • It's PON, I can see it in the back where the cable is connected, so it seems the modem is embed inside the router. Can't a GPON modem be connected to the mobo? – Chazy Chaz Feb 13 '17 at 23:42
  • Isn't this what I would need? finisar.com/optical-transceivers/ftgn2117p2cxn Where can I find the cards? I really have no idea how this things work :( – Chazy Chaz Feb 13 '17 at 23:53
  • I could be mistaken (I'm not a GPON expert either) but I think that thing is for the provider-end of a GPON link, not the customer end. – Peter Green Feb 14 '17 at 0:17
  • Isn't convert from optical to electrical signal what the module/transceiver does? What's the difference then? – Chazy Chaz Feb 14 '17 at 0:50
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    GPON has an upstream/downstream model with a single upstream node serving multiple downstream nodes over a single fiber. Different wavelengths are used for upstream and downstream communications and the upstream end acts as a timing master for multiple downstreams. – Peter Green Feb 14 '17 at 1:16
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The easiest way is to configure the ZTE F680 in bridge mode. That way the TV and telephone ports on the F680 will still work (if you use those services). The F680 will bridge the Internet VLAN to its LAN ports and you can just connect a typical Ethernet router's WAN port to it.

If you want to bypass the F680 altogether, you need a GPON Class B+ ONT/ONU SFP module (not Class C++, not OLT) such as the Finisar FTGN2117P2CxN or the ZyXEL PMG3000-D20B. You can plug this into an SFP port on a router or switch and use the same Internet VLAN ID that your ISP has configured on the ZTE F680.

You cannot easily change the SN / Password / LOID on GPON ONT SFP modules, and ISPs use these values to prevent the use of unauthorized ONTs. Unless you can get your ISP to whitelist your SFP module, you may be forced to use bridge mode with their CPE.

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  • ZTE F680 does not support a bridge mode. I have such a router. – Ely Aug 17 '17 at 13:24
  • @Elyasin It is not explicitly called bridged mode. If you leave the PPPoE unconfigured I believe it bridges the Internet VLAN automatically. – Monstieur Aug 17 '17 at 16:47
  • That would be interesting. Any links or documentation about that? I'm still in doubt. – Ely Aug 17 '17 at 17:20
  • The F680 is not listed on this page, but it should behave the same as the rest which bridge by default. I believe you do need to specify which are the Internet and telephone VLAN IDs for it to work. wwwen.zte.com.cn/en/products/access/xpon/201301/… – Monstieur Aug 18 '17 at 6:37

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