Tag Archives: GLC-SX-MM

How to Match Fiber Patch Cable for Your Multimode SFP?

When you prepare to connect some SFPs with fiber patch cords, you may find SFPs are multimode modules while your fiber cables are single-mode. Try to connect those optics to fiber cable, but no green light and the link fails. So multimode SFPs can’t work over single-mode fiber cables. To avoid the wasting of time and money, you should better know well about single-mode and multimode SFPs and fiber patch cords.

Single-mode and Multimode SFP

SFP, small form factor pluggable transceiver, can support the data rate up to 1Gbps. SFPs can be divided into single-mode and multimode modules.

For single-mode SFPs, there are “LX” for 1310 nm and “EX” “EZX” for 1550 nm. Single-mode SFPs are designed to transmit signals over long distances. For example, Cisco GLC-LH-SM-15 compatible 1000BASE-LX/LH SFP 1310nm 15km DOM transceiver, main product information is shown as follows:

  • Wavelength: 1310 nm
  • Interface: LC duplex
  • Max Cable Distance: 15 km
  • Max Data Rate: 1000Mbps
  • Cable Type: SMF

Comparatively, multimode SFPs are identified with “SX”. This kind of optics is specially for short distance data transmission. For instance, Cisco GLC-SX-MM compatible 1000BASE-SX SFP 850nm 550m transceiver, this is a typical multimode SFP.

  • Wavelength: 850 nm
  • Interface: LC duplex
  • Max Cable Distance: 550m over OM2 MMF
  • Max Data Rate: 1000Mbps
  • Cable Type: MMF

SFP-LX and SFP-SX

Single-mode Fiber Cable and Multimode Fiber Cable

Fiber patch cables are used to connect transceivers on your switch/device. You have to buy the right fiber cable type for your optics. Fiber cable has two different categories: single-mode and multimode.

Generally, single-mode fiber cable can support further distance because of lower attenuation, but the price is higher. While multimode fiber cable has a larger core, usually multimode fiber cable is constructed in 50/125 and 62.5/125. It allows multiple modes of light to propagate. When the light passes through the core, the light reflections increases and more data can be transmitted at given time. As the high dispersion during signal transmission, the link distance gets reduced. So multimode fiber cable is for short distance application. Multimode fiber cable is a little more complex than single-mode fiber cable since it includes four different types of OM1, OM2, OM3, OM4. OM1 and OM2 fiber patch cable can support the data rate up to 10Gbps. OM3 and OM4 are laser optimized so that they can be used in high density data center to support the data rate of 40Gbps and 100Gbps. The following table shows how long each kind of fiber cable can reach running at different data rate.

Fiber Mode Cable Type 1GbE 10GbE 40GbE 100GbE
Single-mode OS2 100km 40km 40km 40km
Multimode OM1 275m(SX) 33m(SR) / /
OM2 550m(SX) 82m(SR) / /
OM3 550m(SX) 300m(SR) 100m 100m
OM4 1000m(SX) 400m(SR) 150m 150m

Note: “SR” implies multimode 10Gpbs SFP+.

For more information about single-mode and multimode fiber cable, you can refer to my previous articles:
What Is Single Mode Fiber?
What Are OM1, OM2, OM3 and OM4?

Solutions for Multimode SFP

If you have Cisco Catalyst 3650 WS-C3650-48PS switches with 4x1G uplink ports, to build a 300m-network link, you are gonna purchase fiber patch cable and SFP modules. What kind of optical equipment should you choose?

As to the SFP module, you need Cisco GLC-SX-MM 1000BASE-SX SFP. Or you can spend less money on third-party SFPs with 100% compatibility. Next step, you need to find suitable fiber patch cable to match this type of SFP. Since 1000BASE-SX SFP is multimode, of course you need multimode fiber cable. Considering the distance of 300 meters, OM1 can only reach 275 meters. So OM2 is the best choice for it’s the cheapest and can reach 550 meters.

1000BASE-SX SFP connection

Conclusion

It’s obvious that multimode SFPs can’t work over single-mode fiber cables. When buying SFPs, watch the standards on the label carefully and find if it’s “SX” or “LX”, “EX”. If it shows “SX”, then find multimode fiber patch cable. It’s not very difficult to choose right cable for your SFP modules.

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 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 1000BASE-SX SFP is another type of hot-swappable 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 of 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 digitalized 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 fiber 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 Fiber 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 realize 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.

How to Choose Satisfying Cisco SFP Transceiver Modules?

Today, various types of 1000BASE SFP transceiver modules can be found in the market. But should you choose one for long distance and short distance application? Or buy copper optics? Which brand is the most reliable and cost-effective, Cisco, HP, Avago, etc.? Do the third-party optics operate as well? So how to find satisfying SFP transceiver modules which suit your switch most? Now keep reading this article and you will get the method. Take three most common types of Cisco SFP modules as example.

Three Types of Cisco SFP Modules

This GLC-SX-MM 1000BASE-SX SFP transceiver module is a duplex SFP transceiver for optical communications. It can support the data rate of 1Gbps reaching the distance up to 550 meters over OM2 multimode cable. The GLC-SX-MM transceiver operates at 850nm wavelength. It’s compatible with the IEEE 802.3z 1000BASE-SX standard, which is usually applied in Gigabit Ethernet. There are also GLC-SX-MMD and GLC-SX-MM-RGD SFP modules. “D” of GLC-SX-MMD means Digital Optical Monitoring (DOM) support which supports transceiver monitoring and troubleshooting operations. “RGD” of GLC-SX-MM-RGD refers to rugged (RGD) transceiver module, which features enhanced ESD (electrostatic discharge) protection, and extended operating temperature range.

cisco_glc-sx-mm

The Cisco GLC-LH-SM 1000BASE-LX/LH transceiver is an LC duplex SFP transceiver applied for Gigabit Ethernet network. This module is designed for both short distance and long distance data transmission. If connecting with single-mode fiber patch cable, it can reach up to 10 km. If connecting with multimode fiber patch cable, it can go up to 550 meters. The GLC-LH-SM transceiver operates at 1310nm wavelength. This transceiver is compliant with Multi-Source Agreement (MSA) standards. LX means long wavelengths and LH is short for long haul. 1000BASE-LX is the Gigabit Ethernet standard specified to work over a distance of 5 km over single-mode fiber cable. 1000BASE-LH and 1000BASE-LH/LX are often used by the manufacturers. Thus, we often see 1000BASE-LX/LH instead of 1000BASE-LX.cisco-glc-lx-sm

The GLC-T 1000BASE-T SFP is a hot-swappable input/output device that plugs into a Gigabit Ethernet port or slot, linking the port with the network. It supports the max data rate of 1000Mbps reaching 100 meters links over copper cables such as Cat5, Cat5e or Cat6a. This transceiver is fully compliant with the MSA and 1000BASE-T standards as specified in IEEE 802.3-2002 and IEEE 802.3ab.

glc-t

Original Cisco or Third-party?

“Third-party” means a supplier (or service provider) who is not directly controlled by either the seller (first party) or the customer/buyer (second party) in a business transaction. For fiber optics industry, all fiber optic transceivers are defined by Multi-Source Agreement (MSA). MSAs strictly define the operating characteristics of fiber optic networking equipment. Therefore, as long as a manufacturer complies to MSA guidelines, their transceiver modules will function and operate identically to other manufacturer’s MSA-compliant transceivers. For example, the above fiber optics like GLC-SX-MM, GLC-LH-SM and GLC-T made by FS.COM are completely compatible with Cisco networking equipment.

Whether to buy original or compatible SFPs may depend on the the cost. Original SFPs are much more expensive than the third-party modules. Using the third-party optics can absolutely help you save the cost. Considering the third-party SFPs from the third vendor, you may worry about the quality and compatibility. As to Cisco compatible GLC-SX-MM, GLC-T, GLC-LH-SM SFP modules, lots of vendors can produce these optics. So it’s necessary to ask information about OEMs and compatibility test from your third-party optics supplier.

Conclusion

From the above introduction, you must have a well understanding about three common Cisco 1000BASE SFPs. When choosing SFP modules, you should consider whether it matches the switch port and the cable you have prepared. If you have multimode cable, then you can choose GLC-SX-MM 1000BASE SFP. If you use single-mode fiber cable, you should select GLC-LH-SM 1000BASE SFP. While if your cable is copper category, you have to use GLC-T 1000BASE-T SFP. On condition that your budget doesn’t allow you to buy original brand module, you can buy the third-party optics from FS.COM with Cisco, Avago, HP and other compatible brands. All the optics have gone through test for 100% compatibility. Any question, please contact us via sales@fs.com.

Cisco Switch Controllers Accepted these SFP Modules

A distribution system port connects the controller to a neighbor switch and is used as the data path between these two devices. This paper talk about a few common methods on the models that have these options.

Cisco 4402 controllers have two Gigabit Ethernet distribution system ports, each of which is capable of managing up to 48 access points (AP). Cisco 4404 controllers have four Gigabit Ethernet distribution system ports, each of which is capable of managing up to 48 APs per port. The 4404-25, 4404-50, and 4404-100 models allow a total of 25, 50, or 100 APs to join the controller. The Gigabit Ethernet ports on the 4402 and 4404 controllers accept these SX/LC/T small form-factor plug-in (SFP) modules:

  • 1000BASE-SX SFP modules, which provide a 1000-Mbps wired connection to a network through an 850nm (SX) fiber-optic link using an LC physical connector
  • 1000BASE-LX/LH SFP modules, which provide a 1000-Mbps wired connection to a network through a 1300nm (LX/LH) fiber-optic link using an LC physical connector
  • 1000BASE-T SFP modules, which provide a 1000-Mbps wired connection to a network through a copper link using an RJ-45 physical connector

1000BASE-T SFP module

The Cisco 5508 controllers have eight Gigabit Ethernet distribution system ports through which the controller can manage multiple APs. The 5508-12, 5508-25, 5508-50, 5508-100, and 5508-250 models allow for 12, 25, 50, 100, or 250 APs to join the controller. Cisco 5508 controllers have no restrictions on the number of APs per port. However, Cisco recommends using link aggregation (LAG) or configuring dynamic AP-Manager interfaces on each Gigabit Ethernet port to automatically balance the load. If more than 100 APs are connected to the 5500 series controller, make sure that more than one Gigabit Ethernet interface is connected to the upstream switch. The Gigabit Ethernet ports on the 5508 series controller, make sure that more than one Gigabit Ethernet interface is connected to the upstream switch. The Gigabit Ethernet ports on the 5508 controllers accept these SX/LC/T small-factor plug-in (SFP) modules:

  • 1000BASE-SX SFP modules, which provide a 1000-Mbps wired connection to a network through an 850nm (SX) fiber-optic link using an LC physical connector
  • 1000BASE-LX SFP modules, which provide a 1000-Mbps wired connection to a network through a 1300nm (LX/LH) fiber-optic link using an LC physical connector
  • 1000BASE-T SFP modules, which provide a 1000-Mbps wired connection to a network through a copper link using an RJ-45 physical connector

The Cisco Catalyst 6500 Series Gigabit Ethernet interface module is a premier modular multilayer switch and delivers secure converged services from the wiring closet to the core, to the data center, to the WAN edge. Designed to complement the many roles that the Cisco Catalyst 6500 Series plays in a network, Cisco Catalyst 6500 Series mixed media Gigabit Ethernet modules offer the broadest selection of media, densities, performance, interoperability, and chassis deployments for enterprises and service providers. The Cisco Catalyst 6500 Series Gigabit Ethernet Interface Module accept these SX, LX/LH, ZX and CWDM/DWDM SFP modules:

  • GLC-SX-MM, 1000BASE-SX SFP (multimode only) Dual LC connector
  • GLC-ZX-SM, 1000BASE-ZX SFP (single mode only) Dual LC connector
  • GLC-LH-SM SFP, 1000BASE-LX SFP (single mode only) Dual LC connector
  • GLC-T SFP, 1000BASE-T SFP (copper twisted pair) RJ-45 connector
  • CWDM-SFP-1470=*, Cisco CWDM SFP 1470 nm; Gigabit Ethernet and 1G/2G FC
  • DWDM-GBIC-60.61***, 1000BASE-DWDM 1560.61 Nm GBIC (100 GHz ITU grid)

Related Article:

Netgear AGM731F Compatible SFP for Gigabit Ethernet and Fibre Channel Applications
SFP Transceiver Module for Cisco 3560 Series Switches