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Wired Networks Thread, 10GB SFP+ LRM Transceivers in Technical; Hi All, Following on from one of my previous threads, we are looking to upgrade our backbone to 10gb, with ...
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    10GB SFP+ LRM Transceivers

    Hi All,

    Following on from one of my previous threads, we are looking to upgrade our backbone to 10gb, with 1gb to desktops. This will include a new core switch and distribution/edge switches, along with new network cabinets (existing ones too shallow) and 10GBe network cards for our VMware hosts.

    I'm planning to do this as a phased approach - this year tackling the core switch, server links and the two network cabinets that feed our IT and Media suites.

    Our fibre was installed, I would estimate, in the late 90s - so I would assume it is OM1? We have one fibre link installed more recently than this - this appears to be OM2. I'd been working on the basis that we'd need to replace this with OM4.

    HOWEVER. I've been looking at the 5406zl as a core switch as suggested by many here, and see that HP do an X132 10G SFP+ LRM transceiver which is described as "up to 200m on legacy multimode fibre". This is where my knowledge is a bit thin. I've googled around "legacy multimode fibre" and it appears to cover OM1 and OM2. I've looked at the fibres coming to our core - pic below...

    IMAG0405.jpg

    The thin brown one is the most recently installed, it is labelled "ETK OPTICAL CABLE 8X1 50/125 LSZH" (so this is OM2)
    The thick green one is labelled "INTEX LOOSE TUBE 8 X 62.5/125" (so this is OM1)
    The thin green one is labelled "FIBRE OPTIC CABLE AASL6204A" (no idea what this is - googling it returns nothing)
    The two thick blue ones have no writing on at all that I can see.

    The HP spec sheet for the LRM transceiver says we are good for 220m on 62.5um fibre and 100m on 50um fibre. So the top two should be OK.

    Anyone with experience of fibre cabling any ideas what the two thick blue ones could be and the thin green one?! Our longest fibre run is approx. 90m.

    Also, anyone have experience on using LRM transceivers on the older spec fibres?

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    Michael's Avatar
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    Generally speaking OM1 is grey, OM2 is orange, OM3 is bluey/green as is OM4.

    OM3 and OM4 are only available in 50/125µm and not 62.5/125µm. OM1 and OM2 are available in both and you can only tell by looking at the writing on the cabling itself.

    To the best of my knowledge OM3 or better is required for 10Gbps, unless the likes of HP have managed to squeeze more out of OM1 and OM2 - but if that's the case, only at comparatively short distances - maybe 30-50m for OM1 and 60-80m for OM2.

    OM3 can handle 300m at 10Gbps and OM4 500m to give you an idea of scale.

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    Quote Originally Posted by Michael View Post
    Generally speaking OM1 is grey, OM2 is orange, OM3 is bluey/green as is OM4.

    OM3 and OM4 are only available in 50/125µm and not 62.5/125µm. OM1 and OM2 are available in both and you can only tell by looking at the writing on the cabling itself.

    To the best of my knowledge OM3 or better is required for 10Gbps, unless the likes of HP have managed to squeeze more out of OM1 and OM2 - but if that's the case, only at comparatively short distances - maybe 30-50m for OM1 and 60-80m for OM2.

    OM3 can handle 300m at 10Gbps and OM4 500m to give you an idea of scale.
    Thanks Michael. This is a quote from the HP technical specifications of their X132 10G SFP+ LC LRM Transceiver (J9152A)

    Cable type: 62.5/125 μm or 50/125 μm (core/cladding) diameter, graded-index, low metal content, multimode fiber optic, complying with ITU-T G.651 and ISO/IEC 793-2 Type A1b or A1a, espectively (a mode conditioning patch cord may be needed in some multimode fiber installations);
    Maximum distance:
    0.5-220m with 62.5 μm multimode cable @ 160/500 MHz*km
    0.5-220m with 62.5 μm multimode cable @ 200/500 MHz*km
    0.5-100m with 50 μm multimode cable @ 400/400 MHz*km
    0.5-220m with 50 μm multimode cable @ 500/500 MHz*km
    0.5-220m with 50 μm multimode cable @ 1500/500 MHz*km
    Notes For OM3 cable (50 μm multimode @ 1500/500 MHz*km), a mode-conditioning patch cord is not required. Other multimode cables may require modeconditioning patch cords to achieve the maximum distances listed above. For fiber patch cords, use Ultra Physical Contact (UPC) surface termination/polish. Angled Physical Contact (APC) is not recommended.
    I've googled LRM SFP+, and it seems the LRM standard was ratified later than SR & LR. But I've not had any experience with them and was wondering if others had? Our distances certainly fit within the limits, but as there is no text on the two blue fibres, and the text on the thick green one doesn't tell me anything useful, I don't know what I'm dealing with on those.

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    Michael's Avatar
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    It all looks correct, but legacy fibre would or should most likely cover OM1 and OM2. Part of me still thinks 'how have HP done this?' and just how reliable it is in practice.

    It may be worth talking to a fibre expert, as buying these modules could be an expensive mistake. In theory though if it didn't work, you'd need to install OM3 fibre to correct the issue.

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    Yeah, it is an odd one. The two companies I've had on site so far have said we'll need OM3. Neither of them mentioned the LRM SFP+'s as an option. I've still got two companies to come on site and quote, so I'll ask the question. I assume there must be some way to test the existing fibre and identify with accuracy whether it will be suitable for 10gb over LRM transceivers?? Rather than taking a punt? Clearly no supplier is going to take that punt if they then have to subsidise the cost of replacement transceivers - it's just easier for them to recommend OM3 from the outset.

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    You can get away with 10g on OM1 and 2 as long as it's under 100m.
    I would however advise upgrading to OM3. Last time I looked OM4 was still overpriced compared to OM3 and offered little to no advantage, especially if all your runs are under 100m.

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    Thanks Marshall_IT. What would the benefit be in upgrading to OM3, if we could utilise our existing OM1/OM2 fibre? Anything I should be aware of?

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    To give some perspective; upgrading our existing fibres has been quoted at approx. £2,700. The additional cost for the LRM transceivers (12 required) over and above SR would be approx. £1,500. So the price differential is £1,200.

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    Quote Originally Posted by smarties11 View Post
    Thanks Marshall_IT. What would the benefit be in upgrading to OM3, if we could utilise our existing OM1/OM2 fibre? Anything I should be aware of?
    Like I said you can get away with it, official distances are om1 33m om2 82m, there are companies that have longer distances and it's worked, but if you start getting errors you can end up getting passed around and people blaming this even when it works.

    As far as the benefits of going with om3 I'll refer you to the table below and say, if you can get the funds to start changing now you might as well because it might not be too far away you'll be wanting 40gb.

    Type 1gb. 10gb. 40gb. 100gb.
    Om1. 275m. 33m. 0m. 0m.
    Om2. 550m. 82m. 0m. 0m.
    Om3. 550m. 300m. 100m. 100m.
    Om4. 1000m. 550m. 150m. 150m.

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    localzuk's Avatar
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    One thing to note is that OM1/OM2 should be FDDI grade in order to work well with LRM. If it isn't, the length you get might be less than expected.

    Also, LRM transcievers appear to be significantly higher cost than others (prices I can find that don't look dodgy seem to have the LRM HP transciever at > £400 each, but SR HP transcievers at ~£200 each.

    For piece of mind, I'd really be pushing to update to OM3 or OM4, to ensure it is all as it should be.

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    Quote Originally Posted by Marshall_IT View Post
    Like I said you can get away with it, official distances are om1 33m om2 82m, there are companies that have longer distances and it's worked, but if you start getting errors you can end up getting passed around and people blaming this even when it works.

    As far as the benefits of going with om3 I'll refer you to the table below and say, if you can get the funds to start changing now you might as well because it might not be too far away you'll be wanting 40gb.

    Type 1gb. 10gb. 40gb. 100gb.
    Om1. 275m. 33m. 0m. 0m.
    Om2. 550m. 82m. 0m. 0m.
    Om3. 550m. 300m. 100m. 100m.
    Om4. 1000m. 550m. 150m. 150m.
    Those distances are for 10GBase-SR, not 10GBase-LRM.

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    Quote Originally Posted by localzuk View Post
    One thing to note is that OM1/OM2 should be FDDI grade in order to work well with LRM. If it isn't, the length you get might be less than expected.
    Thanks for the useful info localzuk. I guess this will be difficult for me to establish given that two of the fibres have no writing on them (will check the remote ends after school but the core ends have nothing on in the 2m or so that I can expose under trunking).

    I've worked out the price differential (replacing fibres vs more expensive LRM transceivers) to be about £1,200 - which isn't terrible given that phase 1 of this is probably going to cost us £20k. Just trying to make the best of what we have, and save some cash. Additionally two of our fibres feed external blocks and run in underground ducting. I can see where both enter their respective ducts but can't find where they resurface. So I'm conscious that there may be additional cost in exploring this - or even having to find alternatives such as a catenary wire.

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    localzuk's Avatar
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    For that difference in price, I'd really recommend going OM3/OM4 then. Its just worth it for the peace of mind.

  14. Thanks to localzuk from:

    smarties11 (2nd July 2014)

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    Thanks for your input localzuk. Sounds like that is what we should do, in that case. Will have to keep my fingers crossed that the cable guys are able to use the existing ducting!

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    We use HP LRM trancievers over various lengths of OM1. We've found it works well over shorter runs, for longer runs it's usually a case of try it and see. On all of our OM1 LRM connections we use a mode conditioning cable at both ends (http://www.universalnetworks.co.uk/p...1302090760.pdf), if you use these be sure to get them the right way round so that the conditioning joint is on the TX side of the transceiver.

    Jona

  17. Thanks to Jona from:

    smarties11 (2nd July 2014)

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