How are "S-Class" Transceivers different from Non "S-Class" Transceivers
When designing high-speed connections, 10G and 40G transceivers have to be carefully selected. Optimizing modules can improve performance and will absolutely impact cost-efficiency. That is why it is so important to distinguish between the various transceiver options. In this case, we can take a close look at the difference between S-Class and non-S-Class Cisco modules.
What Are S-Class Modules?
The term comes from Cisco nomenclature. Cisco makes four specific 10G S-Class module types that have the letter ‘S’ in their names. These groups of modules have stripped away a number of features in an effort to make them easier to deploy and operate. The specifics of those features will be covered in later sections, but the primary reason for this is that S-Class modules can run in normal temperature settings in data centers.
The four modules range from 850 to 1550nm operating wavelengths. They primarily operate within 300m connections, and all four draw either 1 or 1.5W.
What Are Non-S-Class Modules?
Any Cisco 10G module that is not a member of the S-Class falls into the larger group of non-S-Class. Because there are so many more non-S-Class modules, the specifications and applications vary much more widely. Non-S-Class modules can have the same appearance, interface, wavelength, size or power consumption as an S-Class module, but there will still be notable distinctions.
Breaking Down the Major Differences
The main difference between S-Class and non-S-Class is that S-Class transceivers cuts out additional features. What does that mean specifically? When we look at operational metrics, those features and differences emerge.
Protocols
One of the major features cut in S-Class design is protocol support. S-Class modules only support Ethernet. Non-S-Class modules still typically support FCoE, OTN, WAN-PHY and Ethernet.
You will also find that S-Class modules are not TAA certified, but non-S-Class are.
Operating Temperatures
All four S-Class modules operate between 0 and 70℃. Non-S-Class operating temperatures vary by module. The full range of available operating temperatures is between -40 and 85℃.
Transmission Distances
This is a major point of difference between the module classifications. S-Class modules are primarily designed for data center applications. For 10G and 40G applications, they work best inside of 400m distances. Each module has a different maximum transmission distance, with the highest getting up to 80km.
When choosing from non-S-Class modules, transmission distances vary widely, getting above 80km. For long-range applications, there are specialized non-S-Class modules that will outperform S-Class options.
Transceiver Compatibility
The question of compatibility is inevitable. Are S-Class and non-S-Class modules cross-compatible? The short answer is that it depends. There is some cross-compatibility, but it is not universal.
As of now, the only cross-compatible modules operate at 1310nm. The two modules that fit this description are the SFP-10G-LR-S and the X2-10GB-LR.
Price Differences
Price is the primary motivation behind the S-Class design. Cutting features allows the modules to be produced at a lower cost. When applications stay within the primary use case for S-Class modules, they will typically be much more cost-effective than their non-S-Class counterparts.
Cisco produces enough transceivers to cover vast use cases. S-Class modules are designed for some of the most common applications in an attempt to bring costs down. For primary data center usage, they are competitive. For long-range applications or niche uses, there is usually a specialized module that will outperform the S-Class options.
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