Difference Between Cisco GLC-LH-SM and GLC-LH-SMD

Edited by Diffzy | Updated on: September 15, 2022


Difference Between Cisco GLC-LH-SM and GLC-LH-SMD Difference Between Cisco GLC-LH-SM and GLC-LH-SMD

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Since the rapid development of technology, routers and transistors have been in use. Another device that aids in transporting information and data through wavelengths appeared alongside them. It had the name transceiver. The transceiver includes, among others, the GLC-LG-SM-RGD, GLC-LH-SM, and GLC-LH-SMD. These SFP transceiver types are offered as modules for manufacturer switches. For 1Gbps Ethernet networks, Cisco SFP GLC-LH-SM and Cisco SFP GLC-LH-SMD are both utilized. They are interoperable with one another and support the IEEE 802.3 1000BASE-LX/LH standard. Single-mode and multimode LC fiber patch cables can be used to link the two Cisco SFP modules. If a switch can accommodate Cisco SFP GLC-LH-SM, it can also adjust Cisco SFP GLC-LH-SMD.

One could occasionally feel perplexed by the large variety of Cisco SFP modules. Because the differences between some SFP modules like the Cisco SFP GLC-LH-SM and Cisco SFP GLC-LH-SMD—are negligibly slight. You won't know which Cisco SFP module to use for your switch if you can't tell the difference between the two. Cisco SFP transceiver modules for Gigabit Ethernet and Fiber Channel applications have also gained popularity due to the extensive use of Cisco routers and switches. One of the Cisco SFP transceiver modules is the Cisco GLC-LH-SM/Cisco GLC-LH-SMD. Cisco's 1000BASE LX/LH SFP transceiver module is called Cisco GLC-LH-SM. Cisco announced the GLC-LH-end-of-sale SMs in March 2013.GLC-LH-SMD has taken its position. In this study, a comparison between the Cisco GLC-LH-SM and GLC-LH-SMD will be made.


The critical distinction between the Cisco GLC-LH-SM and GLC-LH-SMD is that the former is compatible with DOM, which aids in its digital monitoring and optical capabilities, while the latter is not, resulting in lower visual monitoring levels. Additionally, there are significant differences in the temperatures at which the two are most active. The Cisco GLC-LH-SM is a transceiver, a piece of digital hardware that combines the functions of a transistor and a receiver. Hence, the term "transceiver." One of the initial generations of transceivers produced by the Cisco group gradually lost popularity. However, some customers still use the GLC-LH-SM version in their homes or places of business.

To assist business outlets with converting electric and optical signals to one another and thereby create a non-readable communication channel between multiple units. The Cisco GLC-LH-SMD is another type of transistor-receiver combination produced and marketed by the Cisco groups. This might be regarded as Cisco's second generation of transistors. It is the transceiver that is used most frequently. Cisco SFP GLC-LH-SM and Cisco SFP GLC-LH-SMD vary in that the latter contains an extra letter "D." Meaning of the letter "D."

Two different types of misunderstandings exist around "D." Others believe that "D" stands for "duplex." Cisco SFP GLC-LH-SMD supports the duplex interface. However, a duplex LC patch cable should be used to link Cisco SFP GLC-LH-SM. Aside from copper SFPs, almost all SFP transceiver modules are interfaced with duplex ports. So it's clear that this perception is incorrect. Second, D is sometimes mistaken for the word "rugged." This viewpoint is also untrue. For instance, the Cisco GLC-LX-SM-RGD Compatible 1000BASE-LX/LH SFP 1310nm 10km DOM Transceiver uses the abbreviation "RGD" for "rugged."

Difference Between GLC-LH-SM and GLC-LH-SMD in Tabular Form

Tble: Cisco GLC-LH-SM Vs. GLC-LH-SMD
Parameters Of Comparison
Compatible with DOM
Temperature for Optimal Operation
0 to 70 degrees C
-5 to 85 C
Sale finished
still not
Retail Price
Higher than average
Does Storage Apply
Digital Optical Monitoring (DOM)
does not also support functionality.
the GLC-LH-SMD also supports functionality
Customer Preferences
Market demand
No more demand in the market.
Still demanded in the market

What Is A GLC-LH-SM?

The transistor and receiver built within the device give it its name, or transceiver. The device's 1000BASE LX/LH slight variant, designated as GLC-LH-SM, has to be modified layer by layer to match the consumers' preference for pocket-sized, user-friendly devices. It is a Cisco-produced factor-plugged transportation module type made for MMF and SMF. A dual connection mechanism aligned with LC/PC connections is included in its connection portals. Regardless of the connecting location, this type of connection is referred to as a Duplex LC connector. The standard 1310nm wavelength is ideal for identifying and transmitting electric and optical signals by GLC-LH-SM. If the surrounding circumstances are reasonable, it can travel a minimum distance of 10 cm at a data transfer rate of about 1 GB/s.

It lacks the DOM since it is a prototype for Cisco's transceivers (digital optical monitoring). Transceivers employ DOM to provide an interface that can access various optical properties that are useful for both digital and visual communications. This is a significant flaw in the initial batch of transceivers. However, it costs less and is often compatible with Cisco's subsequent model releases. When in operation, GLC-LH-SM requires model coupling to fulfill its intended purpose.0-70°C is the ideal temperature range for the GLC-LH-SM to function at its peak. Temperatures above or below are thought to decrease the transceiver's activity, making it unusable. The traditional transceiver 1000BASE LX/LH Ethernet Or Gigabit Ethernet requires an efficient voltage of about 3.3 volts. In 2013, GLC-LH-SM transceivers ceased selling their products. However, despite falling out of favor, consumers continue to utilize it.

 Benefits Of Cisco GLC-LH-SM Optical Modules

  • The Cisco GLC-LH-SM SFP optical module doesn't require configuration and may start working immediately, cutting down on installation time. To maximize the system's data flow, it also provides internal calibration.
  • The plug-and-play Cisco GLC-LH-SM SFP optical module is a hot-swappable transceiver module. It used to take a long time to reconfigure a replacement transceiver module after a transceiver failure, which resulted in downtime. However, with the Cisco GLC-LH-SM SFP, you can insert the replacement without turning the entire system down, bringing your network back up.
  • Multimode and single-mode fiber might be used with the Cisco GLC-LH-SM SFP optical module. For long-distance transmission applications like hospitals or campus networks, single-mode fiber allows a transmission distance of up to 10 km. Working with multimode fiber will enable you to transmit data across a distance of up to 550m at a maximum speed of 1.25 Gbps.


The Cisco manufacturers' second generation of transceivers is known as GLC-LH-SMD. The transceiver complies fully with IEEE version code 802.3z, which places it under the 1000 LX BASE standard. It uses optical monitoring with digital components, as do all transceivers, to transmit the signal type from one to the other. It can transmit light over a distance of up to 10 kilometers and has an astounding wavelength of roughly 1300 nm. A typical transceiver can only communicate over a distance of 5 km. Still, the single-mode fiber (SMF) utilized in GLC-LH-SMD allows it to transmit throughout roughly 10 km. The GLC-LH-SMD can transport data at a rate of up to 1G. Even the GLC-LH-SMD includes a duplex connection accessible in the LC model, much like practically all other transceivers with many versions available. The twin LC/PC connector ports that it is equipped with significantly benefit the connecting points.

Its most attractive and user-friendly feature is its compatibility with DOM, which improves its optical activities and digital reading capabilities. In addition, DOM will develop better additional support for visual monitoring. It is interoperable with most other transceivers made by Cisco manufacturers and sold on the market. However, it is relatively pricey compared to other transceivers, which deters purchasers despite its superb features and compatibility. The GLC-LH-SMD has to operate between -5 and 85 degrees Celsius. Any temperature over or below limits how well the transceiver functions. The optical signals that have been transformed into electrical signals are transferred via a DFB laser service by the transceiver's transmitter. GLC-LH-SMD can be used in various contexts, including storage, IP networks, and LAN, WAN, and MAN networks.

Compatibility Of GLC-LH-SMD

The IEEE 802.3z 1000BASE-LX standard is compatible with the Cisco GLC-LH-SMD. IT may work on multimode fibers with a maximum length of 550m and regular single-mode fiber links with a total distance of 10 km. It DOES work well together. The Cisco GLC-LH-SMD transmitter should be connected through a mode conditioning patch cable when utilized over an older multimode fiber type. Additionally, both devices operate at a 1300nm wavelength and contain a dual LC/PC connection.

To put it more precisely, one may set up your device to monitor optical transceivers in the system either globally or by individual ports. The system will keep track of the temperature and signal power levels for the optical transceivers in the designated ports when this feature is activated. When visual operating conditions fall or climb below the XFP or SFP manufacturer's suggested thresholds, console and Syslog notifications are issued. The primary distinction between the Cisco GLC-LH-SM and Cisco GLC-LH-SMD is digital optical monitoring; however, there are still some further variances. For example, the operating temperature range for Cisco GLC-LH-SM is 0 to 70°C (32 to 158°F), whereas the content for Cisco GLC-LH-SMD is -5 to 85°C (23 to 185°F).

Main Differences Between GLC-LH-SM and GLC-LH-SMD in Points

  • The ideal operating temperature for GLC-LH-SMD devices extends from a negative value of -5°C to 85°C, but the minimum operating temperature for GLC-LH-SM devices is just 0–70°C
  • While GLC-LH-SM has a BASE factor of 1000BASE LC, GLC-LH-SMD has an Ethernet BASE capability of 1000 LX.
  • GLC-LH-SM had been eliminated from the markets, and sales had ceased as the production and bringing down in 2013; nevertheless, GLC-LH-SMD is still in use and in demand today.
  • GLC-LH-SM lacks sophisticated digital optical data monitoring since it lacks DOM compatibility. On the other hand, GLC-LH-SMD is DOM compatible and has improved visual monitoring capabilities.
  • Due to its absence of more modern technical capabilities, the older model GLC-LH-SM is less expensive than GLC-LH-SMD, which costs more and is more in demand by consumers.
  • Many customers still use GLC-LH-SM even though Cisco no longer sells it. Cisco GLC-LH-SM 1000BASE LX/LH SFP almost has the same function as Cisco GLC-LH-SMD, except for the extra DOM function.
  • Both GLC-LH-SM and GLC-LH-SMD are available at Fiberstore. As a result, you may discover pertinent items at Fiberstore at a reasonable price, regardless of whether you still like to use GLC-LH-SM or want to have the new version GLC-LH-SMD.
  • Digital Optical Monitoring (DOM) functionality is also supported by the GLC-LH-SMD transceiver's "D" component. According to the features mentioned above, Cisco SFP GLC-LH-SMD can provide DOM function, whereas Cisco SFP GLC-LH-SM cannot.


The optimal function of the transceivers GLC-LH-SM and GLC-LH-SMD are identical. Thus, there is hardly any difference between them. Transceivers are composed of transmitters and receivers that transform optical signals into air-transmittable electric signals before transmitting them. These electric signals are taken in by the transceiver's receiver section and converted into readable optical signals. The transceiver's functionality is greatly influenced by the operating temperature, which is a significant differentiating element. A linked model conditioning patch would be necessary to improve the qualities withheld in GLC-LH-SMD. Some people like GLC-LH-SM over other new models even though it has been off the market for so long. The industry has seen increased demand for Cisco SFP transceiver modules for Gigabit Ethernet and Fiber Channel applications due to the widespread use of Cisco routers and switches. An SFP transceiver module from Cisco is the Cisco GLC-LH-SM/Cisco GLC-LH-SMD. The Cisco 1000BASE LX/LH SFP transceiver module is called Cisco GLC-LH-SM. Cisco announced the termination of the GLC-LH-SM sale in Match, 2013. GLC-LH-SMD now serves as its replacement.

The IEEE 802.3z 1000BASE-LX standard is compatible with both the Cisco GLC-LH-SM and Cisco GLC-LH-SMD. They work with multimode fibers with a maximum length of 550m and conventional single-mode fiber-optic connection lengths of up to 10km. Therefore, they get along well with one another. The transmitter of the Cisco GLC-LH-SM and Cisco GLC-LH-SMD should be connected through a mode conditioning patch cable when utilized over the older multimode fiber type. Additionally, both devices operate at a 1300nm wavelength and contain a dual LC/PC connection.


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"Difference Between Cisco GLC-LH-SM and GLC-LH-SMD." Diffzy.com, 2023. Mon. 27 Mar. 2023. <https://www.diffzy.com/article/difference-between-cisco-glc-lh-sm-and-glc-lh-smd-632>.

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