Tag Archives: GLC-SX-MMD

GLC-SX-MM VS GLC-SX-MMD VS GLC-SX-MM-RGD VS SFP-GE-S

Cisco is a worldwide leader in the telecommunication industry whose routers, switches are very welcome among the users. To work well with those Cisco networking applications, Cisco SFP transceivers are the best choice. GLC-SX-MM, GLC-SX-MMD, GLC-SX-MM-RGD and SFP-GE-S are different types of Cisco 1000BASE SFP transceiver module. All these transceiver modules comply with IEEE 802.3z 1000BASE standard. And since there are similar specifications for these four transceiver modules, users may be confused when they need to choose one SFP module for their Cisco switches. Here we’ll make a comparison of GLC-SX-MM, GLC-SX-MMD, GLC-SX-MM-RGD and SFP-GE-S transceiver modules to help you choose the suitable one.

GLC-SX-MM VS GLC-SX-MMD VS GLC-SX-MM-RGD VS SFP-GE-S

Which transceiver module will you choose?

Cisco Transceiver Datasheet

Here are the datasheets of these four different Cisco SFP transceiver modules.

GLC-SX-MM Datasheet

The GLC-SX-MM is programmed to be fully compatible and functional with all intended Cisco 1GB switching devices. This transceiver module operates on ordinary multimode fibre optic link spans of up to 550 meters in length.

Transceiver Module
GLC-SX-MM
Interface
LC duplex
Wavelength
850nm
Tx Power
-9.5 ~ – 3dBm
Receiver Sensitivity
< -17dBm
DOM Support
No
Temperature Range
0 to 70°C (32 to 158°F)
Cable Type
MMF
Price(US dollars)
6.00
GLC-SX-MMD Datasheet

The GLC-SX-MMD 1000BASE transceiver module is made for multimode fibre only. It’s the replacement of GLC-SX-MM which features an enhanced DOM interface. And this SFP fibre transceiver module operates on legacy 50 µm multimode fibre links up to 550 meters.

Transceiver Module
GLC-SX-MMD
Interface
LC duplex
Wavelength
850nm
Tx Power
-9.5 ~ – 3dBm
Receiver Sensitivity
< -17dBm
DOM Support
Yes
Temperature Range
0 to 70°C (32 to 158°F)
Cable Type
MMF
Price(US dollars)
6.00
GLC-SX-MM-RGD Datasheet

The GLC-SX-MM-RGD transceiver module is designed for Industrial Ethernet applications, including factory automation, intelligent transportation system and other deployments in hash environment. Compared with the ordinary transceivers which can endure the temperature ranging from 0 to 70°C，CLC-SX-MM-RGD can survive in the temperature from -40 to 85°C. It can support up to 550 meters of cabling.

Transceiver Module
GLC-SX-MM-RGD
Interface
LC duplex
Wavelength
850nm
Tx Power
-9.5 ~ – 3dBm
Receiver Sensitivity
< -17dBm
DOM Support
Yes
Temperature Range
-40 to 85°C (-40 to 185°F)
Cable Type
MMF
Price(US dollars)
6.00
SFP-GE-S Datasheet

The Cisco SFP-GE-S transceiver provides a high performance and cost-effective small form factor pluggable module for 1000BASE-SX Gigabit Ethernet and 1G Fibre Channel application. It’s designed for short wavelength applications. The max distance for this transceiver module is 550 meters. Besides, it also supports DOM.

Transceiver Module
SFP-GE-S
Interface
LC duplex
Wavelength
850nm
Tx Power
-9.5 ~ – 3dBm
Receiver Sensitivity
< -17dBm
DOM Support
Yes
Temperature Range
0 to 70°C (32 to 158°F)
Cable Type
MMF
Price(US dollars)
6.00

Differences of GLC-SX-MM VS GLC-SX-MMD VS GLC-SX-MM-RGD VS SFP-GE-S

From the above Cisco transceiver datasheet, we have learned that these Cisco transceiver modules share many similarities. All of them can support up to 550 meters over multimode fibres. And they are designed with the same 850m wavelength, Tx power and LC duplex interface. The main difference is the DOM (Digital Optical Monitoring) function and operating temperature.

·DOM function

Except GLC-SX-MM, all the others support DOM. With this function, users can monitor the transceiver module’s parameters in real time like optical input and output power, temperature and so on.

·Operating Temperature

GLC-SX-MM, GLC-SX-MMD and SFP-GE-S can work at the same temperature ranging from 0 to 70°C. But GLC-SX-MM-RGD SFP transceiver can work in a wider operating temperature of -40 to 85°, which is especially suitable for industrial Ethernet switches.

Conclusion

According to the above discussion, we can say GLC-SX-MM, GLC-SX-MMD, GLC-SX-MM-RGD and SFP-GE-S transceivers share many similarities. However, please note that the differences still exist, and ensure the transceiver module you choose will be compatible with the existing networking equipment. FS.COM is the one-stop shop to help you get these Cisco transceivers and other networking products that are compatible with the Cisco transceivers. If you have any questions in buying guide, please contact us via sales@fs.com.

What’s the Difference Between Cisco GLC-SX-MM and Cisco GLC-SX-MMD?

Cisco 1000BASE SFPs keep a huge market share in the optic area. Cisco SFPs offer users optical solutions for long distance and short distance transmission. For short distance, there are 1000BASE SX SFP, such as Cisco GLC-SX-MM and Cisco GLC-SX-MMD. Though these two modules have great similarity, they are actually different. Then what’s the difference? This article will introduce the details of Cisco GLC-SX-MM and Cisco GLC-SX-MMD SFP transceiver modules.

glc-sx-mm

Cisco GLC-SX-MM

Cisco GLC-SX-MM 1000BASE-SX SFP is a duplex transceiver for short distance transmission, operating at the wavelength of 850 nm at the data rate of 1Gbps. It connects with OM2 multimode LC patch cords supporting up to 550 meters. The hot-swappable 1000BASE-SX SFP is compatible with the IEEE 802.3z 1000BASE-SX standard. And it’s RoHS compliant.

Cisco GLC-SX-MMD

Cisco GLC-SX-MMD 1000BASE-SX SFP is another type of hot-swappable optical transceiver for short reach data transmission. This 1000Base-SX transceiver supports data rates up to 1.25Gbps. Same to Cisco GLC-SX-MM SFP, it also has duplex LC interference. Connecting with OM2 MMF, it can support the distance up to 550 meters. It’s compliant with SFP Multi-Source Agreement (MSA) standards. Cisco GLC-SX-MMD is composed of five parts: the LD driver, the limiting amplifier, the digital diagnostic monitor, the VCSEL laser and the PIN photo-detector. The Digital Diagnostic Monitoring (DDM) function is its special feature.

DDM of GLC-SX-MMD

From the above content, you can see the main difference between these two transceivers is the DDM. When you buy SFP transceivers in the market, you may come across this selection difficulty whether to choose an SFP with DDM or not. So what’s DDM?

DDM is short for digital diagnostic monitoring. It’s also known as diagnostic optical monitoring (DOM). Diagnostic monitoring interface outlined in the SFF-8472 MSA is an extension of the serial ID interface defined in the GBIC specification, as well as in the SFP MSA. Today, many SFP transceivers have the function of digital diagnostics monitoring according to the industry standard MSA SFF-8472. It provides the important information about the status of the transmitted and received signals. This approach allows for better fault isolation and error detection.

DDM mainly plays the role in two sides: monitoring and warning. It monitors detailed information about a transceiver. And it offers a system of alarm and warning flags which alert the host system when particular operating parameters are not in line with the normal operating parameters set by the factory. So users can find out the fault isolation according to outcomes of DDM, and predict failure possibilities and prevent such fault.

Real-time monitoring—With a 2-wire serial bus (also known as “I2C” or “I2C” protocol), digital diagnostics can monitor the SFP module’s temperature, receiver power, transmitter bias current, and transmitter power by a microcontroller inside the transceiver. Usually, the output of the physical value of each parameter is an analog voltage or current from the Trans impedance amplifier, the laser driver, or the post amplifier. Then the digitalised value can be processed as part of a control loop, trigger an alarm, or just record the data into a register.

Calibration and warning thresholds—In addition to generating digital readings of internal analog values, DDM can also produce various status bits. Calibration and warning thresholds value is made during the device manufacturing process. Comparing current values generated by DDM and factory preset limits, users will know whether or not the transceivers have met the desired operation requirements.

FS.COM Cisco Compatible GLC-SX-MM SFPs

FS.COM brings Cisco compatible 1000BASE-SX SFPs including GLC-SX-MM and GLC-SX-MMD SFPs.
The 1000BASE-SX standard optics are developed to support lower cost multi-mode fibre runs in horizontal and shorter-length backbone applications. The following figure shows two Cisco GLC-SX-MM SFP transceivers are connected by an LC MMF patch cable.

glc-sx-mm-connection

Item Part No. Description
a. 11774 Cisco GLC-SX-MM Compatible 1000BASE-SX SFP 850nm 550m Transceiver
b. 43132 2M LC UPC to LC UPC Duplex 2.0mm PVC(OFNR) OM2 Fibre Optic Patch Cable
b. 11774 Cisco GLC-SX-MM Compatible 1000BASE-SX SFP 850nm 550m Transceiver

Note: you can use GLC-SX-MMD SFPs to replace GLC-SX-MM SFPs for shorter-length backbone application, too.

Conclusion

This article introduces Cisco GLC-SX-MM and Cisco GLC-SX-MMD SFP transceivers. Both kinds can realise short distance connection. The difference is that GLC-SX-MMD has DDM function while the other has no. So it’s up to you to decide whether you need DDM function to monitor parameters of the SFP. Fiberstore supplies optical transceivers with DDM and without DDM to satisfy customers’ different needs. If you need more information, please contact us via sales@fs.com or visit our site www.fs.com/uk.

Related Article: A Quick Overview of Cisco 1000BASE-T GLC-T SFP Copper Module

What’s Your Opinion Of Using 3rd Party SFP Modules On Cisco Catalyst Switch?

In general, the cost of an original brand SFP module is more expensive than a 3rd party one. Take Cisco 1000BASE-SX SFP (GLC-SX-MMD) for example, the list price of Cisco is about $ 500.00, but you can easily find a 3rd party SFP modules that can take a discount at up to 90% off. As the cost of SFP transceiver keep adding up over time, many labs or companies are seeking for SFP alternatives to help cut down the costs on these expensive modules. However, a frequent customer problem with Cisco’s new line of Catalyst switches is that they do not support 3rd party (non-Cisco) SFPs – or at least they do not seem to. If you’ve just replaced your network switches and tried using any 3rd party SFPs to connect your network backbone, you’ll quickly stumble across an error similar to the following:

Error message

%PHY-4-UNSUPPORTED_TRANSCEIVER: Unsupported transceiver found in Gi1/0/0
%GBIC_SECURITY_CRYPT-4-VN_DATA_CRC_ERROR: GBIC in port 65538 has bad crc

When you see this error, it means that your Cisco Catalyst switch has just disabled the GBIC port. Why? When a SFP is inserted into a switch’s GBIC port, the switch immediately reads a number of values from the SFP and if it doesn’t like what it sees, it throws the above error message and disables the port. Simple to understand, your Cisco Catalyst switches are configured by default not to work with the 3rd party (non-Cisco) SFPs.

As we know, all SFP modules contain a number of recorded values in their EEPROM that include:

  • Vendor Name
  • Vendor ID
  • Serial Number
  • Security Code
  • CRC

How To Solve This Issue & Successfully Use 3rd Party SFPs On Your Cisco Switch

When the errors displayed, many users will be very nervous and even begin to regret using the 3rd party SFPs. Is there no hope for a solution when facing such situation? Just be relax, the following content will give you some tips on it.

There are two undocumented commands which can be used to force the Cisco Catalyst switch to enable the GBIC port and use the 3rd party SFP.

3750G-Stack(config)# service unsupported-transceiver

Warning: When Cisco determines that a fault or defect can be traced to the use of third-party transceivers installed by a customer or reseller, then, at Cisco’s discretion, Cisco may withhold support under warranty or a Cisco support program. In the course of providing support for a Cisco networking product Cisco may require that the end user install Cisco transceivers if Cisco determines that removing third-party parts will assist Cisco in diagnosing the cause of a support issue.

3750G-Stack(config)# no errdisable detect cause gbic-invalid

When entering the “service unsupported-transceiver” command, the switch (eg. 3750G) will automatically throw a warning message as a last hope to prevent the usage of a 3rd party SFP. The “no errdisable detect cause gbic-invalid” command will help ensure the GBIC port is not disabled when inserting an invalid GIBC. In addition, since the service unsupported-transceiver is undocumented, if you try searching for the command with the usual method “service ?”, you won’t find it.

According to the test, Cisco 2960G, 3560G, 3750G, 4507R and 4507R-E Catalyst switches all accept both “service unsupported-transceiver” & “no errdisable detect cause gbic-invalid commands” commands without a problem. In fact, if the Catalyst switch is running IOS 12.2(25)SE and above, the undocumented commands are available.

Opinion on 3rd Party SFP Modules

People have different opinions on “Whether I should use 3rd party SFPs”. It seems a difficult question for them as the attractive price but unknown performance of the 3rd SFPs. In fact, take Catalyst 3750 Series Switches for example, starting from 12.2(25)SE release, the user has the option via CLI to turn on the support for 3rd party SFPs. However, you should remember that the Cisco TAC will not support such 3rd party SFPs. In the event of any link error involving such 3rd party SFPs the customer will have to replace 3rd party SFPs with Cisco SFPs before any troubleshooting can be done by TAC.

Thus, it is very necessary to use quality assurance SFP modules. Actually, there are some high quality SFP modules OEM vendors, such as Fiberstore. You would not worry about the compatibility of the usage. Because there is a perfect system from the production to shipment. All the products are tested before they shipped and ensure the 100% compatible and high quality. In addition, you can save more as the price is also very competitive.

GLC-SX-MMD sfp modules

Some common types of SFPs supported on Cisco Catalyst 3750 Series Switches

  • 1000BASE-LX/LH SFP (GLC-LH-SM=)
  • 1000BASE-SX SFP (GLC-SX-MM=)
  • 1000BASE-ZX SFP (GLC-ZX-SM=)
  • 1000BASE-T SFP (GLC-T=)
  • 1000BASE-BX SFP 1490nm (GLC-BX-D=) (12.2(25)SEB and later)
  • 1000BASE-BX SFP 1310nm (GLC-BX-U=) (12.2(25)SEB and later)