In-Depth Guide to SFP-10/25G-CSR-S Dual-Rate Transceiver

The existing 10G networks are dejected as demanding applications grow. 10G-to-25G migration thus become a hot topic. Dual-rate 10/25G optics such as SFP-10/25G-CSR-S deliver a simple migration road.

What is SFP-10/25G-CSR-S?

SFP-10/25G-CSR-S, a Cisco 25GBASE transceiver module, is based on the SFP28 (Small Form-Factor Pluggable) form factor. “10/25G” refers to the optional data rate at 10GbE or 25GbE. “CSR” stands for Cisco Short Reach. The max transmission distance depends on fiber type. OEM Cisco SFP-10/25G-CSR-S transceiver supports a link length of up to 300m over OM3 MMF (multimode fiber) and 400m over OM4 MMF at 10G or 25G. For full 25 Gigabit Ethernet operation, FEC is required on the host port. The 10/25GBASE CSR is compliant with IEEE 802.3by and IEEE 802.3cc, interoperating with other 25G interfaces.

 

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10/25GBASE-SR Specification

The Cisco 10/25GBASE-CSR SFP28 specification is shown in the table below. 

Cisco SFP-10/25G-CSR-S Price

For the SFP-10/25G-CSR-S price, the original one is quite expensive. According to ITPrice, the SFP-10/25G-CSR-S list price is $1,291.91. and the sale price is $498.00. For most SMBs and enterprises, It's almost the budget for a piece of system equipment. The following table is a comparison price list of 10/25G-CSR-S modules by different Cisco module providers.

 

 

Third-party vendors such as QSFPTEK also provide Cisco-compatible 10G/25G CSR transceive modules, which are affordable equivalence to costly Cisco transceivers. These third-party dual-rate 10G/25G SFP28 modules have been fully tested on Cisco host devices, which can interoperate with most Cisco equipment. For instance, a pack SFP-10/25G-CSR-S by QSFPTEK only charges you $29, which is negligible compared to the Cisco OEM price.

 

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SFP-10/25G-CSR-S vs SFP-25G-SR-S Benefits

You may not be familiar with the SFP-10/25G-CSR-S that we focus on today, but you must know 25GBASE-SR, a standardized specification for 25GbE short range. Both are SFP28 form factor modules, what set the 10/25G CSR module apart from the standard 25G SR module are:

 

• Support 10G or 25G dual-rate

• Extend fiber reach from 70m/100m to 300m/400m over OM3/OM4

• Interoperate with traditional IEEE 25GBASE-SR and 10GBASE-SR optics

 

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Why Dual-Rate 10/25G is Important?

Bridge the Transmission Gap Between 10G and 25G Short Reach 

Over OM3/OM4 MMF, the 10GBASE-SR SFP+ module supports a max link of 300m or even 400m, which is often the distance that a cabling closet may be located from the data center. 

 

 

Based on IEEE802.3 10GBASE-SR specification, legacy 10G network architecture allows for 300m/400m reach over OM3/OM4 MMF. However, the existing 25GBASE-SR optics cannot reach that far. In another word, the 25G SR module will not work for the same fiber link that 10G SR reaches. To bridge the distance gap, Cisco networks develop the 10G/25G dual rate module to extend the 25GbE connectivity to 300m/400m.

 

Interoperate with 10G, 40G and 100G Optics

10G./25G Dual-rate capability ensures SFP-10/25G-CSR-S is fully compatible with 10GBASE-SR and 25GBASE-SR modules. Also, the 10/25G SRs can interoperate with the 40GBASE-SR4 transceiver to achieve a 4× 10G breakout solution. Similarly, while working with 100GBASE-SR4, the 10/25G SR SFP28 support 4× 25G breakout links.

 

 

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Dual-Rate 10/25G Transceiver Portfolio Introduction

As 10G networks are being deployed for various high-demanding scenarios, the 10G/25G dual-rate optics that meet enterprise demand of seamless upgrading to 25G are facing the request for longer reach. Thus Cisco develops new arrivals of long-reach 10/25G pluggable transceivers, including SFP-10G-LR-S, and SFP-10G-LR-S-I. Bidirectional (BiDi) 10/25G modules, SFP-10/25G-BXD-I, and SFP-10/25G-BXU-I also come out for simplex fiber applications.

 

All module requires RS-FEC on the host ports for operation at 25G.

 

Cisco SFP-10/25G-CSR-S

This is a Short Reach 10/25GBASE-CSR SFP28 Module for MMF applications. The Cisco 10/25G CSR enables a 10G or 25G fiber link up to 300m over OM3 and 400m over OM4 or OM5. While using OM2 MMF, it can run 82m at 10G, and 70m at 25G. SFP-10/25G-CSR-S is designed for 

 

Cisco SFP-10/25G-LR-S

A 10/25G Long Reach (LR) SFP28 module for Single-Mode Fiber (SMF) applications. The

10/25GBASE-LR extends a 10G or 25G fiber link up to 10km through G.652 SMF. The LR SFP28 dual-rate 10G/25G transceiver has wide adoption in enterprises, data centers, and service provider networks that use SMF for 25G or 10G long-reach transmissions. 

 

Cisco SFP-10/25G-LR-I

In contrast, the standard 10/25GBASE-LR SFP28 working temperature range is COM 0 ~ 70°C. This SFP-10/25G-LR-I is an industrial-grade model of SFP-10/25G-LR-S. It can ensure wider temperature thresholds, the IND -40 ~ 85°C. 

 

Cisco SFP-10/25G-BXD-I

SFP-10/25G-BXD-I is an industrial-grade BiDi module. It transmits a signal at 1330nm and receives the signal at 1270nm.

 

Cisco SFP-10/25G-BXU-I

SFP-10/25G-BXU-I is also an industrial BiDi optic. It transmits a signal at 1270nm and receives the signal at 1330nm.

 

Two BiDi 10/25GBASE-BX transceivers are for 10G/25G single-fiber bidirectional applications. They support a max transmission distance of 10km via simplex G.652 SMF at optional 10G or 25G speed. Simplex fiber is a fiber cable with only a single strand, which can save fiber costs. The BiDi 10/25G SFP28 carries data through a single fiber in both directions, doubling your network capacity.

 

specification

Final Words

SFP-10/25G-CSR-S dual-rate transceivers, fully interoperable with 10GBASE-SR and 25GBASE-SR optics, are a solution for seamless 10G to 25G migration. Besides, with the capability to work with 100GBASE-SR4 and 40GBASE-SR4, it can also replace 25GBASE-SR and 10GBASE-SR for breakout solutions. For a converged network with legacy 10G architecture and 25G upgrading side, the 10/25G transceivers provide you with a simple and affordable way to gradually upgrade the network while reusing the existing architecture.

 

For longer applications, SFP-10/25G-LR-S supports a max 10km link. In enterprises, operators use 10/25GBASE-LR SFP28 to connect the distribution switch to the wiring closet or the core switch. In data centers, 10/25G LR is used to connect the ToR switch to servers or leaf switches. In Service providers, They are used to link the service provider end to the customers’ end.