How to Use DOM in Cisco System

Do you know that there is a fiber tester inside your optical transceiver? This "fiber tester" we call it DOM, which is short for Digital Optical Monitoring. DOM is a feature which enables the monitoring of some interesting status values on the interface with the most useful values being the optical receive and transmit powers. You can configure your Cisco (or other brand) device to monitor optical transceivers in the system, either globally or by specified port(s). When this feature is enabled, the system will monitor the temperature and signal power levels for the optical transceivers in the specified port(s). CONSOLE messages and SYSLOG messages are sent when optical operating conditions fall below or rise above the optical transceiver manufacturer’s recommended thresholds. By being able to monitor transmit and receive power levels of optical interfaces you are able to characterize the fiber loss and isolate any unidirectional connectivity issues. So, how to use DOM for your optical transceiver in Cisco system is our main topic today.

What Parameters are Monitored by DOM?

DOM allows to monitor some parameters so that network administrators can then check and ensure that the module is functioning correctly. These real-time operating parameters include:

• Optical Tx power
• Optcal Rx power
• Laser bias current
• Temparature
• Transceiver supply voltage

How to Use DOM

Restrictions

There are some restrictions of using DOM in Cisco system including:

• Ensure that your optical transceiver supports DOM. For Cisco original optical transceivers, you need the transceiver module compatibility information for configuring transceiver monitoring.
• In case of combo ports with SFP and RJ45 provision, when SFP is inserted in slot or port and media type is not configured to SFP, DOM is functional only if global transceiver monitoring is enabled.
• CISCO-ENTITY-SENSOR-MIB traps are sent only once after the threshold violation. However, SYSLOG traps are sent according to the monitoring interval.

Procedure

	Command or Action	Purpose
Step 1	enableExample: Router> enable	Enables the privileged EXEC mode.• Enter your password if prompted.
Step 2	configure terminalExample: Router# configure terminal	Enters the global configuration mode.
Step 3	transceiver type allExample: Router(config)# transceiver type all	Enters the transceiver type configuration mode.
Step 4	monitoringExample: Router(config-xcvr-type)# monitoring	Enables monitoring of all optical transceivers.
Step 5	monitoring intervalExample: Router(config-xcvr-type)# monitoring interval 500	(Optional) Specifies the time interval for monitoring optical transceivers. Valid range is 300 to 3600 seconds, and the default value is 600 seconds.

In conclusion, there are three main command that can be used to turn on/off DOM for all transceivers type in the system:

• Router(config)#transceiver type all
• Router(config-xcvr-type)#monitoring
• Router(config-xcvr-type)#end

Once enabled, DOM can be accessed via CLI using "show interface transceiver command", shown as the following picture:

DOM is incredibly handy when troubleshooting fiber issues. A low value in the Rx Power column indicates that you have a bad fiber, or more commonly, a dirty fiber optic patch cable somewhere.

Of all the five values, two mostly used and relevant values are TX and RX power, and temperature is also used sometimes. The operating range of these three values is unique across all modules and is available in the data sheet. Additionally, there is an extension available for this command, which is also very helpful and is used to check threshold values of the above parameters like temperature, Tx and Rx. The command is "show interface gig x/y transceiver detail".

How about Non-Cisco Transceiver with DOM

Though DOM is a very helpful functionality of optical transceiver, not all transceivers support DOM in Cisco's optical transceiver products family. For example, the common SFPs, such as the GLC-LX or GLC-SX units that are used by most network engineers on a day to day basis are not with DOM feature.

Why not add this helpful and convenient feature to all transceivers? Actually, Cisco have their own attitude. They think that DOM functionality is worth an extra $300 a pop, putting the cost of a DOM-enabled single mode SFP close to $800. However, DOM functionality is not a novel thing now. Surprisingly, there are some third-party optical transceiver include the DOM functionality but with a low cost. Fiberstore, for instance, as the professional optical transceiver manufacturer and supplier, they can offer Cisco compatible SFP transceivers with DDM or DOM functionality with a low cost. For example, GLC-LX-SM-RGD offered by Fiberstore just at $18.00, GLC-SX-MMD and GLC-LH-SMD at $10.00. But if we want to use non-Cisco transceivers, we need a little different approach to get started with DOM of non-Cisco transceivers. To enable support for non-Cisco SFPs, command "Router(config)#service unsupported-transceiver" is necessary.

Originally published at www.fiber-optic-transceiver-module.com.

Knowledge of 1G 10G Dual-Rate Optical Transceiver

As data centers and enterprises strive to future proof their infrastructures while maximizing their current networks, the flexibility of true dual-rate compliant interfaces eases the transition to higher Gigabit Ethernet systems. This is why the dual-rate optical transceiver has emerged (e.g. Finisar FTLX8571D3BCV and FTLX1471D3BCV). And today, I'd like to talk something about the dual-rate optical transceiver, particularly the 1G/10G dual-rate SFP+.

The following figure shows Finisar FTLX8571D3BCV compatible 1G/10G Dual-Rate SFP+ optical transceiver

As its name suggests, dual-rate optical transceiver is a kind of optical transceiver which can support two different data rates. With the dual-rate optical transceiver, users can achieve the full forward and backward compatibility of their systems with a low cost. The common dual-rate optical transceivers in the today's market is the 1G/10G dual-rate SFP+ transceiver. They are compatible with either 10 Gigabit Ethernet or 1 Gigabit Ethernet fiber interface. There are many different vendors to supply the 1G/10G dual-rate SFP+, but the standards and protocols which they complied with are the same. In general, the 1G/10G dual-rate SFP+ are designed for use in 1 Gigabit and 10 Gigabit Ethernet links over single-mode or multi-mode fiber. They are compliant with SFF-8431, IEEE 802.3-2005 10GBASE-SR/SW, 10GBASE-LR and 1000BASE-SX, 1000BASE-LX. In addition, similar to most modern optical transceivers, digital diagnostics monitoring (DDM) or digital optical monitoring (DOM) functions are also available in the dual-rate SFP+, so that users can monitor many parameters of the transceiver module in real-time. Actually, with the development of technology and the increasing demands on higher Gigabit Ethernet, there are other dual-rate optical transceivers with different package styles or even at different data rates except the 1G/10G dual-rate SFP+, eg. Multi-rate XFP.

In my opinions, the emergence of dual-rate optical transceiver is mostly because of the cost consideration. From 1G to 10G, 10G to 40G, 40G to 100G, and even higher data rate, it means that the development of Gigabit Ethernet is very fast. In other words, the cost of updating the equipment keeps adding up over time. Dual-rate optical transceiver is a cost-effective solution to solve this question. For example, a 1G/10G dual-rate SFP+ can be used in both 1 Gigabit Ethernet and 10 Gigabit Ethernet links which eases the transition from 1Gb/s to 10Gb/s systems. Users can configure to operate the dual-rate optical transceivers at 1GbE or 10GbE in a switch with 10G SFP+ ports and 1G/10GSFP+ ports, but not native 1G SFP ports. And do not have to spend extra cost in buying optical transceivers only support 1G or 10G Ethernet. Of course, if you only need one type of Gigabit Ethernet, you do not need to use the dual-rate optical transceiver. So, at this time, the more cost-effective choice is to buy a corresponding single-rate optical transceiver. Nowadays, 10G Ethernet is the most commonly used type of Ethernet as the 40G and 100G are still developing. Thus, the market of 1G/10G dual-rate SFP+ is not so popular as its first emergence. But it is still applied in 1000BASE-SX 1G Ethernet, 1000BASE-LX 1G Ethernet, 10GBASE-SR/SW 10G Ethernet and 10GBASE-LR 10G Ethernet as a cost-effective solution for 1G/10G Ethernet.

From this paper, you may have an understanding of the dual-rate optical transceiver. No matter you are very familiar with the dual-rate optical transceiver or have no idea of it, I really hope that this paper is useful for you. Of course due to the limited knowledge of me, there may be some inevitable errors and omissions existing in this paper. If it is not appropriate, your critical comments are highly appreciated.

Read more articles about optical transceiver, go to click: Fiber Transceiver Solution blog

The Recognition of Optical Transceiver

Optical Transceiver Overview

What is an Optical Transceiver Module?
A fiber optical transceiver is a device that can send and receive optical information. By using an optical transceiver, network spend less space and steer clear of the necessity of getting a transmitter and receiver in the network. Able to transmit information further and faster than older models, the more recent transceivers are utilized and appearance, creating more compact, smaller sized modules than ever before.

How does it work?
A fiber optic transceiver is a accessory acclimated to forward and accept optical information. There are a number of different components on these devices, including a light source and an electrical component. The transceiver has two ends, one that an optical cable plugs into and accession for abutting an electrical device. Fiber optic transceivers combine a fiber optic transmitter and a fiber optic receiver in a single module. They are arranged in parallel so that they can operate independently of each other. Both the receiver and the transmitter have their own circuitry and can handle transmissions in both directions. In fiber optic data links, the transmitter converts an electrical signal into an optical signal, which is coupled with a connector and transmitted through a fiber optic cable. The light from the end of the cable is coupled to a receiver, where a detector converts the light back into an electrical signal. Either a light emitting diode (LED) or a laser diode is used as the light source.

Principle of Optical Transceiver Modules
Optical transceiver generally includes both a transmitter and a receiver in a single module. The transmitter and receiver are arranged in parallel so that they can operate independently of each other. Both the receiver and the transmitter have their own circuitry so that they can handle transmissions in both directions. The transmitter takes an electrical input and converts it to an optical output from a laser diode or LED. The light from the transmitter is coupled into the fiber with a connector and is transmitted through the fiber optic cable plant. The light from the end of the fiber is coupled to a receiver where a detector converts the light into an electrical signal which is then conditioned properly for use by the receiving equipment.

Application of Optical Transceiver Modules
Optical transceiver, essentially just completed the converted of data between different media, can realize the connection between two switches or computers in the 0-120km distance. Its main function is to achieve the conversion between optical-electrical and electrical-optical, including optical power control, modulation transmission, signal detection, IV conversion and limiting amplifier decision regeneration. In addition, there are some functions like security information query, TX-disable. Here is a summary in the practical application.

1. Optical transceivers can interconnect with switches.
2. Optical transceivers can interconnect between the switch and the computer.
3. Optical transceivers can interconnect with computers.
4. Optical transceivers can act as the transmission repeater.
   When the actual transfer distance exceeds the nominal transmission distance of the transceiver, in particular, the actual transfer distance exceeds 120km alerts, with 2 sets transceiver back to back in the case of on-site conditions allow, repeaters or the use of "optical-optical" conversiona relay, is a very cost-effective solution.
5. Optical transceivers can offer conversion between single-mode and multimode fiber connection.
   When the networks appear to need a single multimode fiber connection, you can use a multimode transceiver and a single-mode transceiver back-to-back connections, which can solve the problem of single multimode fiber converted.
6. Optical transceivers can offer WDM transmission.
   The lack of resources of long-distance fiber optic cable, in order to improve the utilization rate of the fiber optic cable, and reduce the cost, transceiver and wavelength division multiplexer (WDM multiplexer) with the use of two-way information on the same fiber transmission.

Optical Transceiver modules can be classified according to the following aspects.

1. Optical Fiber Type
Single-mode fiber transceiver and Multimode fiber transceiver. The single-mode version has a transmission distance of 20 to 120 km, while the multimode one's is 2 to 5 km. Due to the different transmission distance, the transceivers' transmit power, receiver sensitivity and the use of wavelength will be different.

2. Optical Fiber Count
Simplex fiber transceiver and Duplex fiber transceiver. The simplex version receives the data sent in a single fiber transmission, While the duplex one receives data transmitted on a dual fiber transmission.By definition, single fiber devices can save half of the fiber, a fiber that is in the receive and transmit data, where the fiber is very applicable to resource constraints. These products use the wavelength division multiplexing techniques, mostly using the wavelength 1310nm and 1550nm.

3. Transmission Rate
Transmission rate refers to the number of gigabits transmitted per second, per unit of Mbps or Gbps. Optical modules cover the following main rate: low rates, Fast, Gigabit, 1.25G, 2.5G, 4.25G, 4.9G, 6G, 8G, 10G and 40G.

4. Package
SFP, SFP+, GBIC, XFP, XENPAK, X2, 1X9, SFF, 200/3000pin, XPAK, etc.

Fiberstore Optical Transceiver Solution

Fiberstore is a worldwide leading manufacturer & supplier of compatible fiber optical transceivers. We produce and stock for a full range of transceivers such as SFP Plus (SFP+), X2, XENPAK, XFP, SFP, GBIC. In the market, there are many brands of fiber optic transceiver, HP, Cisco, NETGEAR, Finisar, Dell, etc. The following table is the order information of HP SFP transceiver:

Part No.	Description
SFP-1GT-1MA-HP	HP JD089B X120 compatible 1000BASE-T SFP Copper RJ45 100m
SFP-1G85-5MA-HP	HP JD118B X120 compatible 1000BASE-SX SFP 850nm 550m DDM MMF
SFP-1G31-10A-HP	HP JD119B X120 compatible 1000BASE-LX SFP 1310nm 10km SMF
SFP-1G85-5ME-HP	HP J4858B X121 compatible 1000BASE-SX SFP 850nm 550m MMF
SFP-1G85-5MF-HP	HP J4858C X121 compatible 1000BASE-SX SFP 850nm 550m MMF
SFP-1GT-1MD-HP	HP J8177C X121 compatible 1000BASE-T SFP Copper RJ45 100m
SFP-1G31-10F-HP	HP J4859C X121 compatible 1000BASE-LX SFP 1310nm 10km SFP SMF
BLSFP-1G34-10-HP	HP J9143B X122 compatible 1000BASE 1310nmTX/1490nmRX BIDI SFP 10km SMF

Article Source: The Recognition of Fiber Optic Transceiver

About Optical Transceivers

Optical transceivers are available in many different sizes and support many different cabling media and application speeds. You may hear words like, GBIC, mini-GBIC, SFP, SFP+, XFP and others. These support different rates and have different form factors.

A Gigabit Ethernet interface converter (GBIC) is a standard used for the kind of optical transceivers that can be plugged into switches and media converters. This method of plugging a transceiver into a GBIC module slot of a switch, as opposed to having a fixed interface, is also called hot-swappable since the transceiver is loaded into the switch while the switch is powered on. The GBIC standard is determined in the SFF Committee in document number SFF-8053. GBIC transceivers are offered in the -SX, -LX, and -ZX wavelengths and media ranges.

GBICs were created to provide both a small form factor and the flexibility to plug a number of transceiver types into a common electrical interface for Gigabit Ethernet speeds. When a variety of optical port types are needed, an IT administrator can buy GBICs as needed. This lowers the expense of the overall switch system and gives the IT administrator much more flexibility, since they have the choice of different transceiver types. However, if the switch is intended to mostly have one port type, then it will probably be cheaper and take up less space per port to use a switch with that port type built into it. The back of the device has an electrical adapter that plugs into a switch. The front of the transceiver has a SC connector interface for the two 850nm optical ports suitable for use over multimode fiber. One is used for transmitting and the other for receiving signals.

A smaller kind of the GBIC is called a mini-GBIC or SFP (small form factor pluggable) module. It serves the same purpose as the GBIC but has a smaller footprint. To allow for the smaller footprint, SFPs use LC connector interfaces. SFPs are also offered a 1000-Base-T reference to an RJ-45 interface.

The XENPAK transceiver was standardized in 2001 to support 10 Gigabit Ethernet over fiberoptic media and copper media. These come in a number of optical media types and wavelength ranges and also support copper media using a -CX4 interface. They're much bigger in dimension than GBICs and SFPs. After XENPAK was standardized, XPAK and X2 are created to supply a smaller footprint for 10 Gigabit Ethernet. These products share exactly the same electrical interface as XENPAK but are lighter. The XFP small form factor pluggable transceiver was initially developed in 2003 to supply a smaller form factor transceiver for 10Gbps applications than XENPAX, XPAK, and X2 transceivers.

XFP was created by the XFP Multi-Source Agreement Group prior to the development of the SFP+. XFPs supports 10 Gigabit Ethernet, SONET/SDH, and Fibre Channel applications. In keeping with their small form factor, much like SFPs, XFPs use an LC connector interface. XFPs are set up in a similar fashion to GBICs and SFPs, are available in many media type and wavelengths.

The SFP+ transceiver module was created later to assistance 10 Gigabit Ethernet speeds. It's about 30 percent smaller than an XFP, consumes less power, and is more cost-effective. Figure 1 shows various of transceivers.

Figure 1. Different types of optical transceivers.

Want know more about optical transceiver? Fiberstore would be a good place to find out. They provide a full range of optical transceivers, such as SFP transceiver, X2 transceiver, XENPAK transceiver, XFP transceiver, SFP (Mini GBIC) transceiver, GBIC transceiver, CWDM/DWDM transceiver, 40G QSFP+ & CFP, 3G-SDI video SFP, WDM Bi-Directional transceiver and PON transceiver. All our fiber transceivers are 100% compatible with major brands like Cisco, HP, Juniper, Nortel, Force10, D-link, 3Com. They are backed by a lifetime warranty, and you can buy with confidence. You also can tutorial about optical transceivers on they website.

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