{"id":2766,"date":"2026-05-12T03:34:14","date_gmt":"2026-05-12T03:34:14","guid":{"rendered":"https:\/\/lp.szlogic.cn\/products\/40gbase-er4-reach-compatibility-and-deployment-guide-2\/"},"modified":"2026-05-26T08:13:21","modified_gmt":"2026-05-26T08:13:21","slug":"40gbase-er4-reach-compatibility-and-deployment-guide","status":"publish","type":"post","link":"https:\/\/lp.szlogic.cn\/ru\/products\/40gbase-er4-reach-compatibility-and-deployment-guide","title":{"rendered":"40GBASE-ER4: Reach, Compatibility, and Deployment Guide"},"content":{"rendered":"
\"40GBASE-ER4:<\/figure>\n\n\n\n

In modern high-speed optical networks, 40GBASE-ER4<\/a> is a widely used QSFP+ optical transceiver<\/a> standard designed for long-reach 40 Gigabit Ethernet transmission over single-mode fiber (SMF). It is primarily deployed in scenarios where network links must span up to approximately 40 km, making it a critical solution for data center interconnects, metro aggregation, and enterprise backbone networks.<\/p>\n\n\n\n

Unlike short-reach or multimode-based 40G optics, 40GBASE-ER4 uses wavelength division multiplexing (WDM<\/a>) technology to transmit four separate 10G signals over duplex single-mode fiber. This allows it to achieve high bandwidth efficiency while maintaining stable signal integrity over long distances\u2014an essential requirement for modern distributed network architectures.<\/p>\n\n\n\n

From a real-world deployment perspective, major vendors such as Cisco Systems and Arista Networks have widely adopted and supported ER4-class optics in their 40G product ecosystems. At the same time, third-party compatible optics manufacturers like LINK-PP<\/a> also provide interoperable solutions that help reduce deployment costs while maintaining compatibility with mainstream switching platforms.<\/p>\n\n\n\n

This guide helps network engineers, procurement teams, and IT architects quickly understand what 40GBASE-ER4 is, where it fits in the network stack, and how to choose the right compatible module for stable long-distance 40G deployment.<\/p>\n\n\n\n

\u2705 What Is 40GBASE-ER4?<\/h2>\n\n\n\n

40GBASE-ER4 is a 40 Gigabit Ethernet QSFP+ modules<\/a> designed for long-distance data transmission over single-mode fiber, typically supporting link distances up to around 40 km.<\/p>\n\n\n\n

In simple terms, it is a plug-in fiber optic module<\/a> used in high-speed network switches and routers to transmit 40G Ethernet signals between two distant locations using duplex single-mode fiber (SMF).<\/p>\n\n\n\n

\"What<\/figure>\n\n\n\n

QSFP+ definition<\/h3>\n\n\n\n

QSFP+ (Quad Small Form-factor Pluggable Plus) is a compact, hot-swappable optical transceiver<\/a> form factor used for high-speed networking.
It supports 4 independent data channels, each typically carrying 10G of traffic, combining to deliver a total of 40G throughput.<\/p>\n\n\n\n

In the case of 40GBASE-ER4, the QSFP+ module uses four wavelengths (WDM technology) instead of four separate physical fibers, allowing efficient long-distance transmission over a standard duplex SMF link.<\/p>\n\n\n\n

Plain-language breakdown of 40GBASE-ER4<\/h3>\n\n\n\n

To understand it quickly:<\/p>\n\n\n\n