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Cisco S-Class vs Non-S-Class Module

Cisco switches and fiber optic transceivers are considered as the benchmarks of the market with a market share more than 50%. With the development of fiber optic network, Cisco has developed a variety of fiber optic transceivers for different applications and has built a system to name each transceiver. For instance, the most commonly used 10G Cisco modules like SFP-10G-SR and SFP-10G-LR have part numbers which can accurately descript their biggest features. SR means “short range” and LR means “long range”. However, customers find the part numbers of some Cisco modules are named with an “S”, like SFP-10G-SR-S and SFP-10G-LR-S. Cisco calls them S-class modules. People might get confused by these Cisco S-class modules. Cisco S-Class vs Non-S-Class module, or SFP 10G SR S vs SFP 10G SR, which one should you choose?

sfp 10g sr s vs sfp 10g sr

Cisco S-Class Module VS Cisco Non-S-Class Module

Cisco only published four 10G S-class SFP+ modules and two 40G S-class QSFP+ modules. The following table listed Cisco S-class modules. Cisco S-class modules seem to have no differences from the non-S-class modules. However, if you read the specification of these modules and the suggestions from Cisco, you will find the differences.

Data Rate S-Class Module Non-S-Class Module Media
10G SFP-10G-SR-S SFP-10G-SR MMF (duplex)
10G SFP-10G-LR-S SFP-10G-LR SMF (duplex)
10G SFP-10G-ER-S SFP-10G-ER SMF (duplex)
10G SFP-10G-ZR-S SFP-10G-ZR SMF (duplex)
40G QSFP-40G-SR4-S QSFP-40G-SR4 MMF (ribbon)
40G QSFP-40G-LR4-S QSFP-40G-LR4 SMF (duplex)

Protocol

The standard non-S-class Cisco modules like SFP-10G-SR and SFP-10G-LR can support three protocols including Ethernet, OTN (Optical Transport Network) and WAN-PHY (Wide Area Network Physics). However, the S-class modules can only support Ethernet protocol.

Temperature Range

Compared with Cisco C-class modules which can be operating with three different temperature ranges, the Cisco S-class modules can only support the commercial temperature ranges which is 0 to 70°C (32 to 158°F).

  • Commercial temperature range (COM): 0 to 70°C (32 to 158°F)
  • Extended temperature range (EXT): -5 to 85°C (23 to 185°F)
  • Industrial temperature range (IND): -40 to 85°C (-40 to 185°F)

Transmission Distance

Cisco has introduced that the S-class modules are suggested to be used in enterprise network. In addition, the operating temperature range is smaller, thus, S-class module is recommended for shorter transmission distance applications compared with other standard modules.

Price

As the performance of Cisco S-class modules are no better than other modules, why did Cisco published these modules? This is because Cisco S-class modules have lower prices, which is also their biggest sale point.

cisco s-class module

Should I Choose Cisco S-Class Module?

In conclusion, S-class can only support Ethernet protocol and has a commercial temperature range, which is suggested to be used in applications that no special long distance, temperature tolerances, or other special features are required. But many people might not select S-class modules, considering about the future use. As Cisco original branded transceivers are expensive, many people will use third party modules which are much cheaper but is compatible with Cisco devices. A Cisco compatible non-S-class module could be much cheaper than a Cisco original brand S-module. But it can provide almost the same performance as the Cisco original branded non-S-class module.

Related Article: Cisco SFP-10G-SR: All You Need to Know

A Comprehensively Understanding of Cisco 10GBASE SFP+ Modules

How to Select 10G SFP+ Modules for Cisco Switches?

10G fiber optic network is being widespread in today’s telecommunication network. A lot of 10G fiber optic devices like switches are being uses, among which Cisco devices are the most commonly used according to statistics. If you choose a Cisco switch, Cisco original brand or Cisco compatible modules like SFP/SFP+ might be needed for transferring between optical signals and electrical signals. This post will offer details about how to select the proper 10G SFP+ module for Cisco switches.cisco compatible modules

Understand 10G IEEE Standards and How Cisco Name Its Modules

10G fiber optic network is mature now, and there is a wide selection of 10G IEEE standards for different 10G networking applications and environments. Before you buy 10G SFP+ modules for your Cisco switches, you should firstly get to know these 10G standards.

10G IEEE Standards

IEEE has defined 10G standards for different transmission distance and transmission media. For instance, there are 10GBASE-SR SFP+ for short distance up to 300 meters over OM3 multimode optical fiber and 10GBASE-LR for long distance up to 10 kilometers over single-mode fiber. There are also standards for 10G transmission over copper cables like 10GBASE-CR and 10GBASE-T. The following table listed the details for the most commonly used 10G standards.

10G IEEE Standards Description
10GBASE-SR Support 10G transmission over wavelength of 850nm via multimode fiber
in short distances: OM3 (up to 300m) and OM4 (up to 400m).
10GBASE-LR Support 10G transmission over single-mode fiber up to 10km
over wavelength of 1310nm.
10GBASE-LRM Support 10G transmission over standard multimode fiber up to 200m
over wavelength of 1310nm.
10GBASE-ER Operate over 1550nm wavelength and support transmission distance up
to 40km over single-mode fiber. Attenuation is required for transmission
distance shorter than 20km.
10GBASE-ZR Support 10G transmission over 1550nm single-mode fiber optic up to 80km.
For short links, attenuation is required to ensure transmission quality.
10GBASE-BX Support duplex 10G transmission over a single single-mode fiber using
two different wavelengths up to 80km.
10G CWDM/DWDM Support 10G transmission over 1550nm single-mode fiber optic up to 80km.
For short links, attenuation is required to ensure transmission quality.
10GBASE-CR Support 10G transmission over Twinax copper cable in very short distance
and offer a cost-effective way for connections within racks.

Product Name of Cisco 10G SFP+ Modules

The naming system of Cisco 10G SFP+ modules is closely related to the IEEE standards. Here I listed several examples for Cisco SFP+ module to better illustrate how Cisco names its 10G SFP+ modules.

10G IEEE Standards Cisco 10G Modules Product Number Example
10GBASE-SR Cisco SFP-10G-SR
10GBASE-LR Cisco SFP-10G-LR
10GBASE-LRM Cisco SFP-10G-LRM
10GBASE-ER Cisco SFP-10G-ER
10GBASE-ZR Cisco SFP-10G-ZR
10GBASE-BX Cisco SFP-10G-BXD-I & SFP-10G-BXU-I; Cisco SFP-10G-BX40D-I & SFP-10G-BX40U-I
10G CWDM/DWDM Cisco CWDM-SFP10G-1470; Cisco DWDM-SFP10G-61.41
10GBASE-CR Cisco SFP-H10GB-CU1M; Cisco SFP-H10GB-ACU7M

For common 10G SFP+ modules, Cisco uses the key words of the standards to name the responding modules. For special modules, Cisco has built another naming system.

SFP+ module

For a pair of BiDi SFP+ modules, letter “D” and “U” is used to the two modules that are used together on each end of the fiber optic link. For instance, SFP-10G-BXD-I & SFP-10G-BXU-I is a pair of BiDi Modules that can support transmission distance up to 10km. Additional numbers are added to mark the transmission distance of the BiDi modules. SFP-10G-BX40D-I & SFP-10G-BX40U-I is a pair of BiDi SFP+ modules that can support transmission distance up to 40km.

For CWDM 10G SFP+ and DWDM SFP+, the wavelength is added in the part number. For instance, CWDM-SFP10G-1470 is the part number of a CWDM SFP+ that is operated at wavelength of 1470nm. If you want a CWDM SFP+ operating over 1550nm, then the product number of this CWDM module should be CWDM-SFP10G-1550. As all the DWDM SFP+ modules are operated over wavelengths around 1500nm, in the product number of Cisco DWDM SFP+ modules, the first two number 1 and 5 is eliminated. For example, DWDM-SFP10G-61.41 stands for a DWDM SFP+ transceiver with operating wavelength of 1561.41nm.

10G SFP+ DAC

For modules like SFP+ direct attach cable (SFP+ DAC) and SFP+ active optical cable (SFP+ AOC) which contains a length of cables, Cisco combines the characters of IEEE standard and number to name its modules. Cisco SFP-H10GB-CU1M stands for 10G SFP+ direct attach copper cable that is one-meter long. Cisco SFP-10G-AOC2M is a 2-meter long 10G SFP+ active optical cable.

Do You Really Need Cisco Original Brand SFP+ Module?

Except IEEE standard and transmission distance, to select the proper 10G SFP+ module should also considerate several other factors like compatibility and costs.

Although Cisco has a wide selection of switches and 10G SFP+ modules, but not every SFP+ modules can work well on every Cisco switches SFP+ port. Before selecting the SFP+ msodule for your Cisco switch, you must make sure this SFP+ is compatible with your switch.

The second important factor is the costs for the SFP+ modules. Why? SFP+ module is just a small part of the whole fiber optic network, but the use amount of SFP+ module is very large. Cisco Original brand SFP+ modules are usually expensive. Thus, select cost-effective modules are necessary. Actually, Cisco Original brand SFP+ module is not the only choice. There are also many third party modules that it compatible with Cisco switches. Generally, prices of third party fiber optic transceivers are much lower than the original brand ones.

SFP+ module

How to Buy Cisco 10G SFP+ Module?

If you have plenty of money, you can directly order the modules from Cisco. However, if you are going to select the third party modules for a cost-effective solution, then the quality and compatibility would be very important. FS.COM is a provider offers a full range of Cisco compatible modules. All its modules are fully tested in original brand switches to ensure the compatibility and quality. What’s more, FS.COM uses the same naming system as Cisco for its Cisco compatible modules and generic fiber optic modules. A list is also offered in the product page of each fiber optic modules showing the compatible switches and platforms. Customer can use the Cisco product number to search Cisco Compatible and generic modules in FS.COM directly.

Related Article:

Cisco SFP-10G-SR: All You Need to Know

A Comprehensively Understanding of Cisco 10GBASE SFP+ Modules

1000BASE-X Media Components

The following set of media components are used to build a 1000BASE-X fiber optic segment:

1. Fiber optic cable

2. Fiber optic connectors

Gigabit Ethernet fiber optic segments use pulses of laser light instead of electrical currents to send Ethernet signals. This approach has several advantages. For one thing, a fiber optic link segment can carry Gigabit Ethernet signals for considerably longer distances than twisted-pair media can. The standard specifies that a full-duplex 1000BASE-LX segment must be able to reach as far as 5,000 meters (16,404 feet, or a little over 3 miles). However, most vendors sell “long haul” versions of 1000BASE-LX equipment that are designed to reach as far as 10 km (6.2 miles) on single-mode fiber. Vendors have also developed “extended reach” versions of 1000BASE-LX single-mode interfaces that can send signals over distances of 70-100 kilometers or more.

In large, multibuilding campuses, the fiber distances can add up fast, as the fiber cables may not be able to take the most direct route between buildings on the campus and a central switching location. Therefore, these long-reach transceivers can be quite useful. The LX interfaces are essential when it comes to building metropolitan area network(MAN) links, in which Gigabit Ethernet is used to provide network services between sites on a city-wide basis.

Fiber optic cable

Both 1000BASE-SX and 1000BASE-LX fiber optic media segments require two strands of cable: one for transmitting and one for receiving data. The required signal crossover, in which the transmitting and one for reciving data. The required signal crossover, in which the transmit signal (TX) at one end is connected to the receive signal (RX) at the ther end, is performed in the fiber optic link. (Related products in: 10GBASE-LR XFP)

Maximum segment lengths for 1000BASE-SX and 1000BASE-LX are dependent on a number of factors. Fiber optic segment lengths in the Gigabit Ethernet system will vary depending on the cable type and wavelength used.

Fiber optic connectors

The original standard recommended the use of duplex SC fiber optic connectors for both 1000BASE-SX and 1000BASE-LX fiber optic media segments. Figure 1 shows a duplex SC connector. Although the standard can recommend a connector, vendors can use other fiber optic connectors as long as they are not forbidden in the standard. For examle, when the 1000BASE-X media systems first became available, vendors used the compact MT-RJ connector on 1000BASE-SX ports.

21   Figure 1, Duplex SC connector
Figure 2 shows the MT-RJ connector, which provided both fiber connections in a space the size of an RJ45 connector. Because the MT-RJ connector takes up about half the space required by the SC connectors, this allowed vendors to provide more 1000BASE-SX ports on swithch.

22 Figure 2, MT-RJ connector

 

1000BASE-X transceivers

Some vendors used the Gigabit Interface Converter (GBIC), which was an earlier form of transceiver module that allowed the customer to support either the 1000BASE-SX or 1000BASE-LX media types on a single port. The GBIC is a small, hot-swappable module that provides the media system signaling components for a Gigabit Ethernet port.

More recently, vendors have developed a small form-factor pluggable (SFP) transceiver, which can be purchased to support several different kinds of Ethernet fiber optic media systems.

The SFP Transceiver is a small module the plugs into a seitch port and uses a small fiber optic connector called the LC connector. Figure 3 shows the smaller LC fiber optic plug, which is used for connections to SFP fiber optic transceivers.

 

23Figure 3, Duplex LC fiber optic plug

Four Families OF 10 Gigabit Ethernet

The IEEE 10 Gb/s standard was first specified in the 802.3ae supplement, which was adopted in 2002. This supplement defined the basic 10 Gigabit system and a set of fiber optic media standards. Subsequent 10 Gb/s supplements have added copper media types, including a short-range copper connection based on twinaxial cable and a twisted-pair media system capable of reaching 300 m.

There are four sets of physical layer(PHY) specification, also called”families”in the standard. which are grouped by their use of the same signal encoding techniques and other elements.

10GBASE-R
Based on 64B/66B signal encoding, this includes the following optical fiber media
systems: 10GBASE-SR, 10GBASE-LR, 10GBASE-ER, and 10GBASE-LRM.

10GBASE-X
Based on 8B/10B signal encoding, including both fiber optic (10GBASE-LX4) and
copper (10GBASE-CX4) media systems.

10GBASE-T
Based on 64B/65B encoding, supporting transmission over twisted-pair cabling.

10GBASE-W
Based on 64B/66B encoding that is encapsulated and transmitted over an OC-192
SONET optical fiber system. This includes the 10GBASE-SW, 10GBASE-LW, and
10GBASE-EW media specifications.

10 Gigabit Ethernet LAN PHYs include five media systems:

10GBASE-SR
10GBASE-LX4
10GBASE-LR
10GBASE-LRM
10GBASE-ER

Each of the LAN PHYs was specified to provide a media system for a specific set of uses. The short-reach systems are intended for connections between switches in a building or a data center, and from switch ports to server interfaces. The long-reach systems, intended for backbone links on campus and enterprise networks, use more expensive. Single-mode laser-based optics to drive 10 Gigabit signals over longer distances, with
ranges from 10 km for the LR system up to 30–40 km for the ER.

The most used fiber Media Components in 10 Gigabit Ethernet:

Multimode fiber optic cable for short-reach applications.
Single-mode fiber optic cables for long-reach applications.
Mode conditioning patch cable for FDDI grade multimode fiber and OM1 or OM2 cables, up to 220m.
Transceiver: The most popular current form is the SFP+ Module.

Fiber-optic-tutorial.com will offer more information about Gigabit Ethernet. You can also buy fiber media components from Fiberstroe.

Learning CWDM Knowledge Follow Me

With the need for greater capactiy of optical communication systems, wavelength divison multiplexing (WDM) technology was developed.
WDM basically puts multiple signals on a single fiber, each one represented by a different wavelength. While early systems utilized two or three wavelengths with relatively wide separation, we would today characterize those as wide wavelength division multiplexing(WWDM) systems, and primarily they employed dual window(Fused Biconic Taper) FBT couplers. These devices typically operated in the range of 810/870/1310nm or 1310/1550nm, with the light sources such as Fabry Perot (FP) lasers or light emitting diodes(LEDs) operating at those wavelengths. Those early systems eventually evolved in what we today know as coarse wavelength divison multiplexing(CWDM) and dense wavelength division multiplexing(DWDM) system. While DWDM is the technology of chocie for long-haul or ultra long-haul(ULH) applications across the network back bones, in metro applications CWDM rapidly filled the gap between DWDM and WWDM systems, yet less expensive and complex than DWDM. Today, CWDM is becoming more widely accepted as an important transport architecture, where up to 18 wavelengths are available for transmitting information over a fiber link in metro or access network.

After i readed some professinal books, i know the agreed technial standards, in many industries, benefi both producers and cosumers by stimulating the uptake of a new technology, reducing costs, and increasing the overall market size of a new technology. CWDM standards have allowed the manufacturers of CWDM lasers and optical filters to commit to mass production of a small range of standardized components that they know will be used by all of telecommunication systems equipment who incorporate standardized components into their designs can reduce their design effort and materials costs.

I will to learn the CWDM standards seriously. In next artcial, i will introduce the stansdards fo you soon.