1. 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?
  2. Is wavelength a defining factor that should be considered/matched or should anything else be used to guide selection?

Sorry I am new to 10G BASE-SR and I can't seem to find a good resource that can confirm if an SFP supported in a Cisco Nexus 5548UP will be compatible with a new service The new service is described as '10 Gigabit Ethernet LAN PHY IEEE 10G BASE-LR10.3125 Gbps +/- 100 ppm 1310nm'
Ultimately I need to understand if a 'cisco sfp-10g-sr' for which the transmitter wavelength spec is described as 850nm is usable.

1 Answer 1


Wavelength and rate are the two big ones. As you're dealing with 10G ethernet, rate isn't in question. (if we were talking about fibre channel, or SONET, then it would matter.)

For your specific case, they are providing service through a 1310nm "LR" (long-reach) interface. The "SR" (short-reach) optics will not work -- wrong wavelength (850nm) and wrong mode (SR will be multimode (62.5 or 50 micron fiber) vs. singlemode (9 micron))

  • Since we are talking 10G optics, do they even make OM3 62.5u fiber? Dec 19, 2013 at 20:15
  • @MikePennington, according to the specs, you can run at least 10GBASE-SR and 10GBASE-LRM on 62.5.
    – YLearn
    Dec 19, 2013 at 21:29
  • correct, I made the bad assumption that everyone needs the distances my company does (i.e. 62.5u limits 10G-SR optics to 100ft). However, nobody makes OM3 62.5u fiber AFAIK Dec 19, 2013 at 21:35
  • All OM3 (and OM4, and OM2) is 50/125. 62.5 is a dinosaur (or OM1)
    – Ecnerwal
    Dec 26, 2013 at 23:36

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