SFP28 ZR: Extra Bandwidth, Extra Distance & Decreased Latency!

The SFP28 format is maturing rapidly!
Already providing 25G over short and medium distances, the format now includes the SFP28 ZR 80km. The established variety of options to select from include:

  • 25G for 100M over OM4 multimode fiber pair (SFP28 SR 25G)
  • 32G fiber channel at up to 2km over single mode fiber pair (SFP28 IR 25G/32GFC)
  • 25G up to 10km over a single mode fiber pair (SFP28 LR 25G)
  • 32G fiber channel at up to 10km over a single mode fiber pair (SFP28 LR 25G/32GFC)
  • 25G Bidi up to 10km over a single single mode fiber (SFP28 BIDI LR 25G)
  • 25G up to 20km over a single mode fiber pair (SFP28 eLR 25G)
  • 25G Bidi up to 20km over a single single mode fiber (SFP BIDI eLR 25G)
  • 25G up to 40k over a sing mode fiber pair (SFP28 ER 25G)
  • 25G CWDM, DWDM, and DWDM Tunables up to 20km (SFP28 eLR CWDM 25G,
    SFP28 eLR DWDM 25G, and SFP28 eLR DWDM Tunable 25G)

The offerings are plentiful, right?

The New Kid in Town

The technology continues to mature, and now distances for this form-factor have taken the forward leap to 80km in C-Temp and I-Temp variations. It’s a pretty impressive feat in such a small form factor and with the modest 2.5W of power dissipation. The iTemp version can use up to 3.5W at the temperature extremes.


Links that currently utilize 80km will see 2.5x the speed when migrating to 25G from SFP+ 10G optics. That 250% jump in speed is noticeable and affords you some breathing room if you’re bumping up against bandwidth constraints.


Smashing the previous distance limitation of 40km, the 80km variation is able to reach remote destinations. 80km allows many regional connections to get an inexpensive speed boost with just a simple upgrade of transceivers. 


This is a grey area. The latency of the SFP28s is theoretically 480ns compared to the 1200ns of their 10G cousins. While that less than a microsecond latency improvement wouldn’t feel like much across a single point to point connection, crossing a network those latencies can add up, so controlling it where you can is wise.

80km 25G Put Into Practice

Now that you know a little bit more about the SFP28 ZR, let’s take a look at where they come into play with the most impact!

  • Businesses and Providers with distributed sites within a regional area
    • Fiber rarely run “as the crow flies” and even when it does, splices and patches may be gobbling up your light budget
  • Feeding the bandwidth starved remote sites
    • For the remote offices, POPs and HUBS that have been squeaking by on 10G connections, faster and more responsive 25G links make remote offices feel like they are next door.
  • Centralizing resources
    • Local and semi-local offices can utilize central resources like NAS more effectively.

If your 80km 10G links are feeling congested and sluggish, if you need to turn up new regional links that require substantial bandwidth now or in the future, or if your current 25G 40km are riding dangerously close to their distance limitation/light budget, then our SFP28 25G ZR 80KM optics are for you!