localzuk Posted June 14, 2017 Posted June 14, 2017 So, one of our sites has an OM1 fibre between 2 buildings. Its old, but so is the temporary classroom block it connects to. I don't really have the funds this year to replace it with something newer but I would like to try and get 10GbE over there for the backbone. I have seen that 33m is the "standard" top distance, but have read some interesting experiments using LR GBICs over older fibre to achieve longer distances (in 1 case over 1km on OM2!). The distance in question is around 50m. Has anyone else tried this? If so, how did you get on?
ellsandell Posted June 14, 2017 Posted June 14, 2017 https://en.wikipedia.org/wiki/10_Gigabit_Ethernet#10GBASE-LRM From this you may have some luck with LRM Optics coupled with mode conditioning patch cables. 1
localzuk Posted June 14, 2017 Author Posted June 14, 2017 https://en.wikipedia.org/wiki/10_Gigabit_Ethernet#10GBASE-LRM From this you may have some luck with LRM Optics coupled with mode conditioning patch cables. I wouldn't need conditioning patch cables would I, as LRM is multi-mode, as is OM1? I'd buy new patch leads though, just to be sure.
ellsandell Posted June 14, 2017 Posted June 14, 2017 I wouldn't need conditioning patch cables would I, as LRM is multi-mode, as is OM1? I'd buy new patch leads though, just to be sure. For OM1/2 you still need a MCP. The MCP is installed between the transceiver and the patch panel. Two MCPs are required per installation. To install the patch cable, follow these steps:Step 1 - Plug the single mode fiber connector into the transmit bore of the transceiver.Step 2 - Plug the other half of the duplex connector into the receive bore of the transceiver.Step 3 - At the other end of the patch cable, plug both multimode connectors into the patch panel.Step 4 - Repeat Step 1 through Step 3 for the second transceiver located at the other end of the network link. Notes for 10GBASE-LRM:For customers using OM3 fiber type, MCP should not be used. It is highly recommended to measure the power level before plugging the fiber into the adjacent receiver. When the received power is measured to be above 0.5dBm, a 5dB attenuator for 1300nm should be used and plugged at the transmitter source of the optical module on each side of the link. Mode Conditioning Patch Cable Tutorial | FS.COM 1
kearton Posted June 14, 2017 Posted June 14, 2017 We ran a couple of 10gig links over OM1 using HP LRM modules. Also needed some special (read: expensive) adapter patch leads. The connections were quite flakey... 1
AlanD Posted June 25, 2017 Posted June 25, 2017 Perhaps I'm not understanding something.... We have several old optical fibre runs....really old...probably even before there was a classification of OM1, OM2....multimode 65u. The runs are over 100m long ...maybe even 200m ..... and we just stuck a 10GB module (Multimode) at each end - bought for £10 each from china - and were pleasantly surprised that the connection worked just fine - with no errors showing up in switch statistics. I am at a loss to understand why you need special patch cables - unless it is to go from 50u to 65u diameter ... we find that cheap optical patch leads of either diameter work just fine. We did get the old fibres reterminated some years ago as a job lot when some new fibre went using replacing the old home made glue and crimp connections with spliced end pieces - which obviously reduced potential loss.. Our switches are netgear..built up over the years for £50 each buying them off ebay so we have been able to move to a 10G backbone for under £2000 - including a spare couple of switches in the cupboard - so we think we have done OK. Each cabinet has 2 x 10G switches with at least 2 x LACP fibres (one from each switch) going to edge switches (we are a physically large campus site). Any switch in the backbone can fail without affecting connections to edge (apart from a potential drop in bandwidth). Cabinets have UPS (again bought cheaply off ebay with new compatible batteries installed)
localzuk Posted June 25, 2017 Author Posted June 25, 2017 I've put in an order for the LRM modules and conditioning patch leads from fs.com, so we'll see how well it goes. Costing about £120 IIRC, plus postage.
mjk Posted June 25, 2017 Posted June 25, 2017 I am at a loss to understand why you need special patch cables - unless it is to go from 50u to 65u diameter ... we find that cheap optical patch leads of either diameter work just fine. It's probably a mode conditioning cable, so that LX can be run over shorter, multimode OM1. I'm guessing your connections are much shorter runs.
3s-gtech Posted June 25, 2017 Posted June 25, 2017 Perhaps I'm not understanding something.... We have several old optical fibre runs....really old...probably even before there was a classification of OM1, OM2....multimode 65u. I spoke to our fibre installers about this a few years ago. Apparently, with pre-OM1 fibre it's more about luck. Because it wasn't produced to a 'standard' (other than being 62.5/125) its capability at sustaining high speeds varies but it's quite possible for it to exceed the specs of OM1, or be short of them. Doesn't surprise me that it'll run 10Gb.
Sheridan Posted June 25, 2017 Posted June 25, 2017 We've done the same, stuck 10gb modules on a mixture of om1,2 and 3 and all have achieved a stable 10gb with the shortest run being about 30m and the longest about 150m. All netgear stuff as we got the modules on offer! The fact we didn't notice any benefit suggests our network was ticking along quite nicely but at least we've future proofed it a bit more!
AlanD Posted June 25, 2017 Posted June 25, 2017 The fact we didn't notice any benefit suggests our network was ticking along quite nicely but at least we've future proofed it a bit more! Yes - I rarely notice our servers capable of saturating 1Gb/s nevermind 10Gbs....the exception is backups when I assume the sequential data can be accessed and moved much quicker that the random access in typical use. Collectively our servers might make good use of the 10Gb/s - but That is atypical - except for copying and backing up data when its good to know that you are not throttling the network for other users.
Blue_Cookeh Posted June 25, 2017 Posted June 25, 2017 Yes - I rarely notice our servers capable of saturating 1Gb/s nevermind 10Gbs....the exception is backups when I assume the sequential data can be accessed and moved much quicker that the random access in typical use. Collectively our servers might make good use of the 10Gb/s - but That is atypical - except for copying and backing up data when its good to know that you are not throttling the network for other users. CCTV is another big one. We record at 1080p30 and with the amount of cameras we've got it doesn't quite saturate 1Gbps, but it's certainly in the 4-500Mbps range. I'm sure I could get that down with a lower resolution but heh, why not?!
localzuk Posted June 26, 2017 Author Posted June 26, 2017 Yes - I rarely notice our servers capable of saturating 1Gb/s nevermind 10Gbs....the exception is backups when I assume the sequential data can be accessed and moved much quicker that the random access in typical use. Collectively our servers might make good use of the 10Gb/s - but That is atypical - except for copying and backing up data when its good to know that you are not throttling the network for other users. 10GbE for us is a future-proofing thing. At the moment, there's no way they'll saturate a 10GbE link. Once we've installed the new VOIP phone system, new IP CCTV, doubled the number of client devices etc...? Who knows. I know we have the funding to do it now, I don't know that we'll have the funding in a few years when we might hit a problem point.
PotNoodleTech Posted September 19, 2018 Posted September 19, 2018 Looking at this here to - a lot of our fibre was put in in 1997. Am thinking of just pulling through new pre-terminated fibre to a couple of the easier buildings to try out.
AlanD Posted September 19, 2018 Posted September 19, 2018 Unless old fibre runs are broken - I can't see why your would replace them. Typically - they will work just fine with a 10G (presumably multimode if they are that old) module in the switch. We did replace some of our mechanical termination joints with pigtails (got a contractor in to do a number in one go). And while using a 50u patch with 64u cable does introduce some loss - our connections worked fine. No errors reported in 10G data on the switch. Only if you are working at the limits of what fibre can do and are getting transmission errors would I think about replacing the fibre.
m25man Posted October 5, 2018 Posted October 5, 2018 I spoke to our fibre installers about this a few years ago. Apparently, with pre-OM1 fibre it's more about luck. Because it wasn't produced to a 'standard' (other than being 62.5/125) its capability at sustaining high speeds varies but it's quite possible for it to exceed the specs of OM1, or be short of them. Doesn't surprise me that it'll run 10Gb. There’s a lot of mis-information in this thread. This explanation however is the best answer by far. I work with both MM and SM both Data and Video (Broadcast) in all sorts of environments and have seen almost every conceivable type of fail. What needs to be understood is that when OM1 (circa 1989) was introduced everything was powered by expensive laser modules. The Purity of the optical Fibre wasn’t anywhere as good as it is now. Over the years data speed requirements have risen and demand has driven technical innovation to reduce the costs of providing it. Everything is relative. Factors like the quality and purity of the Fibre, Output of the light source, sensitivity of the receiver, Bend radius, Insertion Losses and joint/termination quality and alignment factors will all affect the ability of a pair of transceivers to hold a conversation over a given distance. Only by validation using calibrated test equipment will you be certain that your link is satisfactory. Anything else is guesswork. Just because it works today doesn’t mean it will still be working when the temperature drops by 20 degrees or the cheap Chinese SFP you bought suddenly drops its output by 6db after 3 months use or some clown uses a 62.5/125 patch cord on a 50/125 link. A 3db attenuation loss can half your effective transmission distance. Whist whacking a pair of modules at each end of an OM1 might work (initially) and score you a few brownie points with the bursar, you are at that point just another cowboy leaving a legacy of pain for somebody else to have to troubleshoot and fix. If your going to do such a job, get it validated and make sure you document it fully, I’ve wasted too many hours of my life having to track down bizarre network issues caused by F.I.D installs.
3s-gtech Posted October 6, 2018 Posted October 6, 2018 Thanks for quoting me. I am indeed a know-nothing cowboy! The time and money I saved learning this much about fibre, I spent learning other stuff instead. Thank you for the more informed post though.
AlanD Posted October 6, 2018 Posted October 6, 2018 You have nothing to loose buying a couple of relatively cheap Chinese modules and trying it. It may work fine... And if not you will have to dip your hand deeper into your pocket. The only poor modules we have purchased are the genuine badged ones. And ungraded fibre runs work for us well over the minimum distances. You are running a school network., not a bank network.
m25man Posted October 6, 2018 Posted October 6, 2018 Thanks for quoting me. I am indeed a know-nothing cowboy! The time and money I saved learning this much about fibre, I spent learning other stuff instead. Thank you for the more informed post though. You might find this of use.. http://www.sopto.com/learningcenter/ Whilst VCSEL might have dropped the cost of laser module production nothing can really offset the hidden attenuation factors of 1990s Fibre and ye olde hand finished terminations. One only has to look at the Hubble telescope and the repair missions it needed to rectify the effects of poorly finished optics [emoji23] Keep on learning though. ps. 803.bt will be the next big thing in networking, mark my words.
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