In optical networking, 100G ER refers to 100 Gigabit Ethernet Extended Reach. A 100G single-mode optical interface class for extended-reach links, commonly targeting distances around 40 km. Engineers commonly encounter it while planning or operating Metro and long-reach data center interconnects.
The reference framework matters when specifying 100G ER for Metro and long-reach data center interconnects. The applicable IEEE 802.3, ITU-T, or multi-source agreement defines lane count, wavelength, fiber, reach, and interoperability assumptions. A product name or quotation that mentions 100G ER without that context is not yet a complete requirement.
Related term ER / ER4 is relevant but not interchangeable with 100G ER. ER / ER4 is an extended-reach single-mode standard commonly designed for links up to 40 km, whereas 100G ER is a 100G single-mode optical interface class for extended-reach links, commonly targeting distances around 40 km. A design may require both, only one, or a specific combination of them.
When selecting or documenting 100G ER, verify lane count, wavelength plan, fiber type, connector, reach, FEC assumption, and optical power budget. A common mistake is to assume that support for FR / FR4 automatically confirms support for 100G ER; the exact data sheet, host configuration, and test conditions must show that relationship.
Frequently Asked Questions
Are 100G ER and ER / ER4 interchangeable?
No. 100G ER describes a 100G single-mode optical interface class for extended-reach links, commonly targeting distances around 40 km, while ER / ER4 describes an extended-reach single-mode standard commonly designed for links up to 40 km. Confirm both separately when the design uses both concepts.
Where is 100G ER normally used?
Typical use includes Metro and long-reach data center interconnects. The exact implementation still depends on the host equipment, link design, environment, and governing specification.
What should a 100G ER specification include?
It should state lane count, wavelength plan, fiber type, connector, reach, FEC assumption, and optical power budget. These details allow a supplier or engineer to verify the requirement instead of relying only on the term 100G ER.
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