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A Quick Overview of Cisco GLC LH SMD

Cisco GLC-LH-SMD is one of the most popular optical modules in the present times. Want to know all about this amazing wired connectivity solution? Then, read on to find the basics about Cisco GLC-LH-SMD optical module.
GLC-LH-SMD

1. Basics of GLC-LH-SMD optical modules

Important module parameters of Cisco GLC-LH-SMD
The Cisco GLC-LH-SMD Optical Module is an MSA protocol compliant connectivity solution that connects a Gigabit Ethernet port or slot to an optical fiber network. It is also known as 1000BASE-LX / LH SFP transceiver. The following is the table of parameters of this optical module.

Optical module model
GLC-LH-SMD
Package type
SFP
Center wavelength
1310nm
Rate
1000Mbps
Interface
Duplex LC
The maximum transmission distance
10km
Laser type
FP 1310nm
Fiber type
MMF/SMF
DOM function
Support
Transmit optical power
-9-3dBm
Receiving sensitivity
<-21dBm
Commercial temperature
070

Important applications of Cisco GLC-LH-SMD
 
Cisco GLC-LH-SMD optical module is compatible with various optical transmission networks, and applications following protocols such as Fiber Channel, SDH/SONET/ATM, Gigabit Ethernet, and others. This transceiver is functional across variety of switches, routers and server interfaces too.

Cabling specifications for Cisco GLC-LH-SMD Optical Modules
 
Fiber type
Core size
Bandwidth
Transmission distance
MMF
62.5μm
500Hz
550m
50μm
400Hz
550m
50μm
500Hz
550m
SMF
-
-
10km

Cisco GLC-LH-SMD compatible switch models
 
Listed here are a few switch models compatible with  Cisco GLC-LH-SMD . You can find more about the compatible switches at the detailed page of the GLC-LH-SMD optical module

Switch model
2960S-F48TS-L
Cisco WS-C3750X-48PC
WS-X4624-SFP-ECisco 6500
N9K-C92160YC-XCisco 3900
WS-C2960X-48LPD-L
WS-C3560E-48PD
WS-C3650-48FS
Cisco WS-C4500X-40X-ES
C6800-32P10G(-XL)Cisco Nexus
SPA-2X1GE-V2Cisco ASR 9000
WS-C2960XR-48TD-I
WS-C3650-48TQ
IE-2000-16PTC-G-ECisco 4500
WS-X4448-GB-SFPCisco 6500

2. Comparison between Cisco GLC-LH-SM and GLC-LH-SMD

Similarities

Cisco GLC-LH-SM and GLC-LH-SMD are similar in many features. Both of these deliver data transmission reach of 10km at the input wavelength of 1310nm. They are fully compatible with IEEE 802.3 1000BASE-LX/LH standard and thus they can be used interchangeably. At Cozlink, you can find both of these priced at $7.

Differences

The most obvious difference between Cisco GLC-LH-SM and GLC-LH-SMD is whether it has a DDM support or not.

3. DDM Function – Unique aspect of GLC-LH-SMD Transceiver

The letter “D” in GLC-LH-SMD stands for digital diagnostic monitoring function also known as digital optical monitoring (DOM). This feature is introduced as per Multi-source Agreement (MSA) SFF-8472. It serves following purposes:

a. Component Monitoring
Optical Transceivers need monitoring of these parameters so that these crucial connectivity solutions are not overworked and fall prone to fault. These parameters are – laser bias current, transceiver supply voltage, transceiver temperature, average optical power, average optical power transmitted and received, and optical modulation amplitude. If any of these parameters are exceeded, the DDM system warns the system about failure of compliance.

b. Fault Identification and Isolation
DDM enables easy fault isolation and their identification in particular location of optical network system. It issues status flags and using these flags in addition to parametric monitoring data that DDM produces, one can pick the faulty part and ascertain the reason for failed link in no time.

c. Failure prediction in advance
DDM is effective in identifying two basic failures common with optical transceivers such as frequent errors and breakdowns. Based on the transceiver performance parameters report, DDM can predict impending failures of the fiber optic links. Transmitter performance is responsible for breakdowns and frequent errors are attributed to the operating conditions of the transceiver. The knowledge about these conditions can make the failure prevention easier.

4. How Cisco GLC-LH-SMD, GLC-SX-MMD and GLC-ZX-SM optical modules are different

The following table enlists the important parameters of Cisco GLC-LH-SMD, GLC-SX-MMD, and GLC-ZX-SM modules. The table reveals that all three modules are same in delivering data transmission rate, commercial temperature range applicable and interface type. Also, their naming suggests that only GLC-LH-SM does not have DDM support while the other two have this feature.
Product Image
 GLC-LH-SMD
 GLC-SX-MMD
 GLC-ZX-SM
Optical module model
GLC-LH-SMD
GLC-SX-MMD
GLC-ZX-SM
Optical module name
Cisco GLC-LH-SMD SFP Gigabit optical module
Cisco GLC-SX-MMD SFP Gigabit optical module
Cisco GLC-ZX-SM SFP Gigabit optical module
Price
USD7
USD6
USD24
Package Type
SFP
SFP
SFP
Rate
1000Mbps
1000Mbps
1000Mbps
Center wavelength
1310nm
850nm
1550nm
Interface
Duplex LC
Duplex LC
Duplex LC
Fiber Type
MMF/SMF
MMF
SMF
Transmission distance
10km
550m
70km
Transmit optical power
-9-3dBm
-9.5-3dBm
05dBm
Receiving sensitivity
<-21dBm
<-17dBm
<-24dBm
DOM Function
Support
Support
Support
Laser type
FP 1310nm
VCSEL 850nm
DFB 1550nm
Commercial temperature
070°C
070°C
070°C
Application of optical modules
Gigabit Ethernet
Gigabit Ethernet
Gigabit Ethernet
1000BASE-LX
Fiber Channel
Fiber Channel
1000BASE-LH
1000BASE-SX
1000BASE-ZX
Compatible switches
Cisco ME 3600
Cisco Catalyst 3560
Cisco Catalyst 2960
Cisco ME 3800
Cisco Catalyst 3750
Cisco Catalyst 3560
Cisco ME 3900
Cisco Catalyst Express 500
Cisco Catalyst Compact 2960

 
All these modules are good in their area of working. You can pick any of these after deciding your network requirements.

If you require an optical module that can transmit data up to a distance of 70km, GLC-ZX-SM is worth recommending and for shorter data reach, say up to 550m, you can go for GLC-ZX-SM. And if DOM feature is your urgent requirement, you can consider buying GLC-SX-MMD.

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5. GLC-LH-SM vs. SFP-GE-L: Know the Difference

GLC-LH-SM SFP Module
GLC-LH-SM is the name given by Cisco for transceiver suitable for long haul networks. This transceiver is unique in the sense that it can operate on both single and multimode fibers by employing a mode conditioning patch cable. This hot-swappable connectivity option is compliant with IEEE802.3z 1000BASE-LX standard, and can deliver data transmission reach of 10km and 550m on single mode and multimode fibers respectively. Here are the basic parameters of GLC-LH-SM tabulated:

Modules
Interface
Wavelength
Tx power
Receiver Sensitivity
DOM Support
Temperature Range
Cisco GLC-LH-SM
LC duplex
1310nm
-9.5 ~ -3dBm
< -23dBm
No
32to 158     (0to 70)

SFP-GE-L SFP Module
SFP-GE-L transceiver is similar to GLC-LH-SM transceiver on many aspects. Compliant with IEEE 802.3z 1000BASE-LX, this transceiver, like a Cisco 1000BASE-LX/LH Ethernet transceiver is also made compatible with many Gigabit Ethernet applications. The SFP-GE-L transceiver also can deliver data connectivity across both single mode and multimode fibers up to a distance of 10 km and up to 550 m respectively.

Modules
Interface
Wavelength
Tx power
Receiver Sensitivity
DOM Support
Temperature Range
Cisco SFP-GE-L
LC duplex
1310nm
-9.5 ~ -3dBm
< -23dBm
Yes
23 to 185     (-5 to 85)

Notes: Both GLC-LH-SM and SFP-GE-L modules require mode conditioning patch cables when used across 1000BASE-LX/LH applications connected with OM1, and OM2 fiber cables of FDDI grade.

Speaking about differences, the SFP-GE-L SFP transceiver comes with DOM (digital optical monitoring) whereas GLC-LH-SM lacks this feature. Both are different on account of operating temperature range too. SFP-GE-L module is designed to work at extended temperature range of -5℃ to 85℃ while Cisco GLC-LH-SM is operational at the commercial temperature range of 0℃ to 70℃.

6. How 1000BASE- LX, LH and LX/LH are different from each other?

All 1000BASE-LX, 1000BASE-LH and 1000BASE-LX/LH imply Gigabit Ethernet transmissions. Among them, only the 1000BASE-LX is a standard, while the other two terms - 1000BASE-LH and 1000BASE-LX/LH have come into fashion due to their popularity amongst vendors. There are other transmission standards such as 1000BASE-LX10, 1000BASE-EX and 1000BASE-ZX too that are found to be useful in long haul networks. Their differences are more clearly illustrated in the table below:

Name
 Medium
wavelength
Specified distance
1000BASE-LX/LH
9/125 Single mode fiber
1310nm
 10km
1000BASE-LX
62.5/125, 50/125 Multi-mode fiber
1310nm
550m
1000BASE-LX10
9/125 Single mode fiber
1310nm
10km
1000BASE-LH
9/125 Single mode fiber
1310nm
25~70km
1000BASE-EX
9/125 Single mode fiber
1310nm
40km
1000BASE-ZX
9/125 Single mode fiber
1550nm
70km

7. When is EOL declared for Cisco GLC-LH-SM

Cisco GLC-LH-SM which is an LX/LH GE SFP with LC connector has reached its EOL i.e. End of Life. It is fully replaced by another 1000BASE-LX/LH transceiver Cisco GLC-LH-SMD which comes with DOM and works with both SMF and MMF at input wavelength of 1310nm.

With change in popularity and demand, Cisco scraps certain GE SFP Modules. This end of life and end of sale information about the abandoned modules is available at:
https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/transceiver-modules/eol_c51-698060.html

For those looking for Cisco compatible GLC-LH-SMD, Cozlink is the right place to be. This OEM produces Cisco equipment compatible transceivers and other connectivity solutions.

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