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16 Most Common Questions Of Cisco SFP-10G-SR You Need To Know

Communication has been there since the beginning of human race. With the evolution of humans, the technology for communication also evolved.  Social networks are becoming essential in human lives. More advancement is coming up in the communication sector. The speed of transmission is increasing exponentially. Mbps speeds have given way for Gbps speeds. Wireless communication is gaining popularity.

The telecommunications network is quickly heading for a 10G fiber network. Actually, it has gone beyond 10G. People are widely using 10G switches. Cisco is the most popular in the market. If you choose a Cisco switch, you will have to use Cisco compatible modules. Here we will discuss some of the most common questions regarding the Cisco SFP 10G SR module. The contents were mostly inspired from Cisco, Amazon and Quora websites.

1. How Cisco SFP+SR differ from Other Cisco 10G Optical Modules?

Different models have different transmission distance and other specifications. The same SFP+ SR module has different variations in itself. The distance ranges from 300m to 80km. You can refer the Cisco website for a detailed comparison of features. As transmission distance increases so do the price of the module.
Most of the short distance models use Multi mode Fiber(MMF), while the long distance ones use Single Mode Fiber (SMF). Most of them can withstand a temperature as cold as 0℃.

2. What's the distinction between SFP SR and LR models?

The "SR" denotes "short range", which supports a shortwave (850nm wavelength) multimode fiber (MMF). This can transmit for distances ranging from 2m to 300m. This design has the advantages of low cost, smallest fiber module, and less power consumption.
"LR" stands for "Long Range", which supports single-mode fiber (SMF) of long wave (1310nm). The distance can range from 2 km to 10 km or even 25 km. This configuration is characterized by long distance, increased prices and more power consumption.

3. What's the difference between SR and SR-S models?

SR S makes use of S class optics. According to Cisco, these are designed to serve enterprise and data center 40G and 10G. You may think that the S class will cost more. But it is actually the opposite. By avoiding unwanted features, S-class is actually cheaper than non-S-class.
Apart from this, S-class supports Ethernet only. It is not compatible with Optical transport networks. Moreover, S-class and non-S-class optics operate in different temperature ranges. Thus, if you don’t need any special features like extra tolerance for temperature, S-Class optics can save you a considerable amount of money.

4. What are the main distinctions between SFP-10G-SR and SFP-10G-T?

Both of them are hot-pluggable with a calculated soft-start. They are interoperable with any SFP+ connector system and cage. On the other hand, they have entirely different performance when it comes to the 10G switches. The T module uses the Cat6a cables for a 30+ m link length and not RJ45 cables. Whereas, SR operates with OM3 cables and uses LC connectors. They have a link length of 300m and above.
These transceivers are much cheaper as compared to the lately released 10G copper module.

5.  Compare SFP-10G-SR and SFP-10G-LRM

The "LRM" in 10Giga Base-LRM stands for "Long Reach Multimode. This is primarily used for long-distance multi-point mode of connection. The IEEE 802.3aq standard, using 64B / 66B encoding is used for this. It was released in 2006.
LRM uses 1310nm lasers, while SR uses 850nm lasers. SR stands for Short Range and they support link lengths around 300m over multimode fiber.

6.  What's the difference between SFP Short Range and X2 Short range?

Both of them support link lengths in the range of 300m over MMF and use lasers with a wavelength of 850nm. But they are two different packages belonging to the Cisco 10G family. SFP Modules belong to SFP  package and are used in SFP compatible slots. And X2 modules belong to X2 package and used in X2 compatible slots.
Besides, the X2 model uses SC connector and the SFP transceiver is paired with dual LC connector.

7.  How does ER differ from SR?

ER expands to Extended Reach. These modules can achieve transmission distances of up to 40km over single-mode fiber. ER uses 1550nm lasers and is cross-compatible.
SR is short for Short Range; these transceivers support link length of 300m and use 850nm lasers. Unlike ER, they are transmitted over multimode fiber.

8.  How do ZR and SR differ?

ZR is also a variation of Extended Reach. Unlike ER, they can transmit 10G data rate around 80km distance. Actually, this format is unofficial, that is not technically an IEEE approved standard for networking hardware.
SR is short for Short Range; these transceivers support link length of 300m and use 850nm lasers. Unlike ZR, they are transmitted over multimode fiber. 

9.  What is the specialty of SFP-10G-T-S as compared to 10G-SR? 

SFP-10G-T-S has the same parameters with SFP-10G-T except that they use copper modules. The T S modules use RJ45 connectors.
SFP+ SR operates over OM3 cables with a distance of 300m over LC connectors. 

10.  What does -X in LR-X and SR-X means?

The standard temperature for operation is 0°C to 70°C. Whenever you see -X, such modules can withstand a wider variation of temperature, from -40°C to 85°C. There is no other specialty for X tagged transceivers. In standard working conditions, you need not spend extra for the –X rated modules.
Always minimize the cost so as to optimize your network cost.

11.  Can we use SFP hardware in SFP+ slots?

In many cases, the SFP optical module can be inserted into the SFP +. But there is a general confusion about the compatibility of them both. They may not work in all circumstances. The SFP optical module can operate in the SFP + slot whereas the reverse is not true. If you insert an SFP module on an SFP + port, the speed is brought down to 1G instead of 10G.
The port may lock itself to 1G speed and you may need to reprogram it for upgrading speed. SFP + ports usually can’t sustain speeds below 1G. Thus we can’t use 100Base modules on SFP+ ports.
The scenario varies with switch manufacturers. In the case of Cisco, some SFP modules become compatible with SFP+ slots.  This is not at all possible for Brocade switches. So it is better to adhere to the specifications given by the manufacturer.

12. What factors to consider while choosing the Suitable Fiber Patch Cables for Cisco SFP-10G- SR transceiver?

As far as Ethernet is concerned, the common used pluggable fiber patch cables include the three types: Copper cable, High-speed cables, and fiber patch cables. The copper cables are usually RJ45 cables. High-speed cables include direct attach and active optical cables. The following picture shows these: 
The choice of patch cable depends on the nature of the transceiver and connector. If LC connectors should be used, the LC to LC patch cables is to be used. This will be the ideal choice for a Cisco SFP 10G SR transceiver.

13. Differentiate among single-mode and multimode fiber?

In optic communication, single-mode fiber (SMF) is for the transmission of remote signals over long distances. Light in the single-mode fiber is along the straight line with minimum possible spreading and reflection. So its propagation distance is very far and can transmit over long distances with little attenuation.  They can transmit up to 80 km.  Multimode fiber (MMF) carries multiple light rays. They follow the principle of Total Internal Reflection and are usually used for short distances. They can attain a maximum distance of 2 km.
The core diameter is in the range of (8-10)/125μm for SMF so as to minimize the spreading of rays. MMF uses a wider diameter in the range of 50/125μm,62.5/125μm.
LASER is used as the light source in case of SMF. But for MMF, LED is the preferred light source.
SMF uses a higher bandwidth of 2000 MHz/km while in the case of MMF it is only 50-500 MHz/km.
For SMF, the sheath color is yellow. In the case of MMF, it is orange or aqua green.
As discussed in the first point, SMF has very low levels of dispersion as compared to MMF.
The differences can be summarised as follows:
Transmission Distance
2km (100M),1Km(1G/s),550m(10G/s)
Core Diameter
Light Source
Laser light source
LED light source
Fiber Wavelength
Sheath Colour
Orange or Aqua green
Modal Dispersion
Low dispersion

High dispersion

14. Can we use Cisco SFP+ Transceivers in Other Brands Equipment? 

In the case of cost sensitive users, they hope that they can buy one module and can use it in different brands equipment. So the question arises as to whether we really can use a different transceiver than the Original intended one. The answer is negative in most cases.
Different models of transceivers will have their own special encryption. Runtime verification is done when you insert a different module. If the verification fails, the system shuts down. So it is always safe to use the prescribed equipment only.
However, there are many third-party modules, which are compatible with Cisco equipment. Cozlink is one of the main players. Normally, the price of such modules will be less than the original one. If you are too concerned about cost and willing to compromise on quality, you can go for third party modules.

15. Basic precautions to install and remove 10G SFP+ SR modules

Refer to the following video for instructions on how to install and remove 10G SFP+SR modules


The basic precautions are listed below
1) Installing the module:
      • Though data rates may be same, one module may not be suited for a particular slot. So insert an SFP module preferably into an SFP slot only.
      • Carefully check the compatibilities of each module before connecting it to any slot. If incompatible modules are inserted without caution, a system break down may happen. This can lead to monetary losses as well.
      • Check the network configuration; connect the modules that are best for the current configuration of the network.
      • Always clean the modules before installing, be it an SFP module or SFP+ module. This will prevent contamination in the system.
      • Do not expose your eyes to fiber optic equipment. They emit laser and infrared rays that may be harmful to you. If at all, you need to examine something, make sure that the light source is disconnected.
      • You can damage the electrostatic discharge, if not careful. In order to prevent it, always wear an antistatic wrist strap while handling the network equipment.

    2) Removing the optical module:
        • It is not good to frequently pull out or insert the SFP module. This can badly affect the lifetime of the module.
        • If you need to remove the optical module, please pull out the rod first. Then, through the rod remove the optical module.

    16. Summary of the troubles faced by the optical module at work

    As every other electronic equipment, optical modules also will have some troubles or problems associated with it. We shall discuss some of them.
    • Compatibility issues
    This is one of the most common and frequently occurring problems. There may be many reasons for this. The code for compatibility may not be downloaded properly.
    The required software update may not have been installed.
    • Coding errors
    If programs are not coded carefully, then problems may arise. The proper selection of programmers is essential for the smooth working of optical networks. However superior the hardware may be, a compatible program is always essential.
    • Loss of Product packets
    Some of the possible reasons:
    The device may not match with the electronic function of the optical module. A mismatch can arise between master chip and the device.
    Failure of Physical line or equipment may cause problems.
    Error may seep into Routing information
    • Optical port contamination
    The optical links can become unstable if the optical interface contamination rises above some safety limits. Several reasons can be attributed for this. Some of them are:
    Over exposure to the environment may cause dust particles to enter and contaminate the port.
    If a contaminated connector is used, this can lead to a secondary contamination in the optical ports.
    If connectors have major scratches, this can cause harm to the optical ports.
    The quality of fiber optic connectors should be taken care of. If low-quality connectors are used, the optical ports and modules can get contaminated fast.
    We have seen the frequently asked questions regarding Cisco SFP 10G modules. Hope your questions were answered. More technical information is available in the product datasheet as well as in the company website of Cisco.  

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