Questions tagged [fiber]

Fiber optic data transmission, cabling, connectors, interfaces. Questions should have this tag if they directly involve fiber optic transmission of data, fiber optic cabling and/or connectors, or interface devices directly attached to fiber optic cable.

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85 votes
21 answers
78k views

When to choose fiber instead of twisted pair (copper)

These days both fibre and twisted pair are supporting 1000BASE-T and 10GBASE-T, but when do you choose one over the other? The obvious one is maximum cable length, but what are other factors which ...
56 votes
14 answers
195k views

Multi-Mode and Single-Mode Fiber Differences

When cabling a network using fibre, what is the difference between single-mode and multi-mode fibre? When should I be using one or the other? Are there compatibility and/or speed concerns with either?
  • 915
22 votes
6 answers
14k views

Speed of Light in Copper VS Fiber - Why is Fiber Better?

I'm reading Computer Networks - A Systems Approach 5th ed., and I came across the following statistics for the speed of light through different mediums: Copper – 2.3 × 108 m/s Fiber – 2.0 × 108 m/s ...
  • 331
20 votes
5 answers
41k views

Where to cross RX/TX line in fibre optical cabling

I'm in the process of connecting together some sites via optical fibre. The trans-site multimode fibres are terminated with SC jacks on patch panels from where they are patched to the corresponding ...
16 votes
2 answers
3k views

What is this device used by a networking technology company?

I recently saw two men open up the sidewalk in a major German city. It seemed they dug out this device Both men worked for a networking technology company, so I hope this is on topic here. What is ...
  • 271
16 votes
3 answers
6k views

DWDM active and passive comparison

I am trying to understand the cross-over point for when I would deploy active DWDM over passive DWDM (as active seems to be more expensive based on my initial research); Passive DWDM takes in various ...
  • 5,270
12 votes
5 answers
2k views

Do faster segments of a network mean faster flow rate or lower latency?

This is another one of those hypothetical questions. I've been trying to figure out whether or not having a faster 'segment' of a network in between host A and host B will translate into a faster flow ...
  • 515
10 votes
3 answers
3k views

How can ISPs on one continent connect to ISPs on another continent?

How can ISPs on one continent connect to ISPs on another continent? From a physical layer standpoint? Say one ISP is located in Asia and another one in Europe how would they connect their fiber ...
  • 357
10 votes
2 answers
650 views

Appropriate certificate to ask for a fibre installation (ANSI/TIA-568.3-D?)

I am getting a subcontracting company to provide terminated fibre connections between two points, and I want to say what they are expected to do and what certificate they are expected to supply. This ...
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9 votes
3 answers
2k views

What type of fiber do I need for a WS-G5484

I have bought two WS-2948G switches from cisco for a lab. I now need to buy two additional modules for them WS-G5484. I've never worked with fiber so I was wondering if there are differences in fiber ...
9 votes
6 answers
2k views

Do I need to protect SFP ports and optics from dust/contaminants? If so, how?

I have a used switch with some SFP ports and some SFP modules installed, which I don't use. All new switches come with little rubbery bungs that block up unused SFP ports, but since this old procurve ...
  • 655
9 votes
4 answers
24k views

The maximum length of CAT6 for intranet network?

Recently I purchased CAT6 cable with a length of 150 meter. I bought another CAT6 with a length of 148 meter. I joined both the cables using RJ45 cable coupler. I tested it using LAN TESTER, and ...
  • 193
9 votes
4 answers
757 views

FTTH and alternatives

I was listening to a interview regarding the back country and Fiber to the home with the Swedish professor in telecommunications Per Ödling. Once in the interview he was referring to technologies that ...
8 votes
3 answers
1k views

10GigE fiber over a distance of 120km?

If we purchase a single strand of dark fiber which spans 120km, is it possible to light it at 10Gig? We will be using a 6509 switch at one end and a 4948-10GigE at the other end. We have not ...
  • 333
8 votes
3 answers
1k views

10Gig over single strand fiber

We have several BX SFPs in my network and I love them. We're limited on the amount of fiber we can get between buildings (each pair costs $250/month) so the mismatched laser solution gives us ...
  • 1,783
8 votes
5 answers
7k views

Connecting two different Cisco Switches using Fibre

I have two Cisco Catalyst 2960-24TC-L switches and would like to connect them using fibre over a distance of 200Meters. According to cisco, the switches has two SFP ports, which I can clearly see on ...
  • 569
8 votes
6 answers
24k views

Can a single optical fiber support full-duplex communication?

Can a single-mode single optical fiber support full-duplex communication, or does it have to be two fibers, one for each direction?
8 votes
1 answer
500 views

Factors that determine compatibility of SFPs with new fibre services?

Whilst I understand that product recommendations are off topic can anyone help by explaining what the critical factors are when looking for SFPs that are going to be compatible with a new service? Is ...
  • 2,067
8 votes
1 answer
2k views

Are the SFP/SFP+ int's on WS-X45-SUP7-E autosensing?

I have two Cisco Catalyst 4510R+E systems that I am interconnecting, using the interfaces on the sup's (both have dual Sup7-E's.) They are marked 1G/10G Uplinks (SFP/SFP+) on the sup above the ...
8 votes
2 answers
2k views

Cisco Nexus Fabric Extenders with 10G-SFP in path?

We are looking to deploy a new data center build-out with Nexus 7ks and Nexus 2ks(FEX). I know the Nexus 2ks come bundled with the Fabric Extenders to be used to uplink to the Nexus 7ks. Our plan ...
  • 271
8 votes
1 answer
48k views

SFP+ complains threshold violation and went down

All, Recently bought 3 Cisco switches: 3560x and two 2960Xs. 3560 acting as the core switch and other 2 switches are connected using SFP+ (One SFP-H10GB-CU1M and other SFP-10G-SR) I have issue with ...
7 votes
3 answers
1k views

Fiber between two sites - no signal lights

We need to have fiber connection between two sites (distance less than 300 meters from each other). Currently there is multi-mode fiber connected to old switches working nicely. Now we are updating ...
  • 71
7 votes
9 answers
31k views

Is fiber optic Digital or analog? optical signal is digital or analog?

Is fiber optic Digital or analog? optical signal is digital or analog? what kind of signal Fiber generate? I mean traditional phone system is analog, but Ethernet is digital, but what about Fiber ...
7 votes
4 answers
1k views

Why has a fiber optic cable stopped functioning on one of the allowable wavelength? [closed]

For a long time, a fiber cable worked on both allowable wavelengths, and now it does not. Is this a defect of manufacturing? Maybe it's due to weather, other external factors, mechanical damage, or ...
  • 171
7 votes
3 answers
682 views

Determine Core Size of Fiber Run

We have an existing fiber infrastructure that's several years old. I can't for the life of me read the jacket to get the core size of the fiber, and was wondering if there was a way to measure it ...
7 votes
2 answers
1k views

Do low temperatures cause problems installing new optical wiring or fixing broken optical cables by splicing?

One of our supplier reported big problems splicing (using this) a broken outdoor optical fiber cable when temperatures around or little bellow freezing point. They refuse to install new optical fiber ...
7 votes
4 answers
534 views

Building too large for ethernet runs

I'm pretty new to network design. I know enough to wire small buildings and such, but I'm puzzled as to how work this one out. A building I'm working on is an odd shape, and very large. ...
's user avatar
7 votes
3 answers
6k views

Raman amplifier vs EDFA, what is the tradeoff?

For light amplification for longer-haul fiber lines, as far as I can tell, the two major options are EDFA's and Raman amplifiers. What is the tradeoff between one type and the other? Are there areas ...
7 votes
2 answers
651 views

What certifications are there for Fiber Optic termination and splicing?

As a knowledgeable person in computer networks I have always had an itch for learning how to create custom-length fiber optic cables. So, as a personal goal, I want to get trained and certified in ...
6 votes
8 answers
16k views

What do the positive and negative (+/-) transmit and receive pins mean on Ethernet cables?

So I'm trying to understand the pin layout of an Ethernet port, specifically for 8P8C which to my understanding is the most common. Of the eight pins, only four are apparently used for communication, ...
  • 63
6 votes
3 answers
4k views

What is a reasonable latency for a L2 1G leased line between 2 sites, about 420km apart?

We need a dual gigabit connection to one of our customers and for the time being one of the lines has been brought online. The connection is between our DC and the customer's HQ, it's a L2 connection. ...
6 votes
2 answers
4k views

Is it possible to permanently damage optical transceiver if Rx signal is too strong?

Data sheets of optical transceivers often specify the receiver maximum input power. In addition, non-volatile memory of transceivers often seem to hold this data: root@MX240> show interfaces ...
  • 1,295
6 votes
1 answer
488 views

Why is there a separate set of 10 Gigabit fiber-optic transmission standards for WANs/SONET?

So, I'm reviewing the different IEEE transmission standards for an exam, and I've noticed that for the 10GBASE-X standards, there's two different sets of fiber-optic standards, 10GBASE-xW and 10GBASE-...
  • 95
6 votes
1 answer
3k views

1000 Base-LX compatible with 100 Base-FX

I'm trying to connect a Cisco Catalyst 3750 12-port SFP switch to a RuggedCom RSG2100 with fiber ports. The Cisco has a third-party SFP (GLC-LH-SM) that shows in "show interface" as 1000Base-LX, and ...
  • 175
5 votes
3 answers
1k views

Cables on a closed rack

I've just spent the last few days building my first server rack. It will be a significant upgrade to our current mess. I was asked to buy and install one and so I did. I was not completely aware of ...
5 votes
2 answers
2k views

Speed benefits when switching LAN from 1Gb copper to Fiber Optic

We are trying calculate how will the network performance improve when we switch from 1Gb copper LAN to Fiber Optic. We have 5-20 people simultaneously working on a Server via the 1Gb LAN. There are ...
5 votes
2 answers
7k views

Can Ethernet use fiber optic cables?

I am new to networking, know about Ethernet and that Ethernet cables exist to make a wired networks. I also know about fiber optic cables which have a glass like material inside and transmit light ...
's user avatar
5 votes
3 answers
257 views

Are all same type fiber optic transceiver compatible?

Can I order a 1000BASE-LX transceiver from any source and it will be compatible with all others 1000BASE-LX ? Would a link with a Juniper 1000BASE-LX and a TrendNet 1000BASE-LX transceiver work?
  • 51
5 votes
2 answers
72 views

Better throughput with 100 Mb NIC setting

Ran across something very odd today. Just had a symmetrical 100 Mb circuit installed at a site I’m contracting at. When the NIC is set for auto negotiate for duplex and speed, we only get ~96 Mb down ...
5 votes
1 answer
7k views

UDLD state: tx/rx loop detected

Relevant Log messages Feb 1 03:39:08.338 EST: %IPV6-4-DUPLICATE: Duplicate address FE80::212:44FF:FE4D:4400 on GigabitEthernet8/20 Feb 1 03:39:08.904 EST: %UDLD-SP-4-UDLD_PORT_DISABLED: UDLD ...
  • 3,300
5 votes
1 answer
214 views

How to use an optical tap? Which fiber should I use?

We have an optical tap (https://www.fs.com/products/73675.html) that provides an LC connector providing two TX instead of RX/TX. As you can see, there is a conflict. What I think I need: A splitter ...
  • 386
5 votes
1 answer
5k views

Why does my Cisco 4507 core switch not recognize my SFP+?

I have a SFP+ cable of dubious parentage (I think it is a knockoff) that I'm trying to use to connect a Cisco 2960S stack with a 4507 core chassis. I have included what I think is relevant ...
5 votes
1 answer
904 views

Fiber Port Issue

I'm trying to troubleshoot a situation between a foundry sx and a brocade icx. I setup tagged ports and vlans between them both. Now when I connect the 2 switches with an ethernet cable, ospf comes ...
4 votes
2 answers
212 views

Small datacenter fiber management [closed]

I'm in the process of building out a small datacenter ( about 10 racks ) and it feels like the fiber connections for storage and 10G ethernet are really piling up. Does anyone have any products they'...
4 votes
3 answers
5k views

Mixing OM-2 with OM-3/4 Patchcords/Installation Fibers

is it possible to mix OM-2 with OM-3/4 Patchcords or installed Fiber. As far as i know, they are the same diameter of 50µm, they only have different bandwith caracteristics. Is there any other reason ...
  • 143
4 votes
2 answers
214 views

Connecting 2 FCoE Switches together with optical cable

I'm designing a network and have 2 cabinets on each floor, and I'm thinking of using FCoE switches in both cabinets so that I can connect them with fibreoptic cable. I think I can easily find switches ...
4 votes
2 answers
199 views

Noticeable limitations or penalties from using inline fiber couplers

Is there any noticeable limitations or penalties from using inline fiber couplers, such as those in a patch panel to join multiple fiber runs together? Currently I have switches joined together ...
  • 143
4 votes
2 answers
203 views

ELI5 – basic questions regarding MMF

We have a few fiber optic connections between our buildings, and admittedly we haven't a bloody clue about them (other than "all buildings have SMF, except one that has MMF because reasons, and we're ...
  • 259
4 votes
1 answer
228 views

Confused about single strand Fiber media converter or duplex media converter?

As per Title you may understand my question. I have read many articles about WDM technology as well as Tx/Rx on separate optical fiber. Here my question is which is better in real environment? Any ...
  • 43
4 votes
1 answer
2k views

LACP and how to configure switches correctly

I want to set up a fast network and am considering options. I want a backbone switch that connects all my switches together. I can see options for SFP / SFP+ ports. Some SFP ports are 1 or 2 Gb from ...
  • 143

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