The DTX CableAnalyzers are capable of testing both multimode and singlemode fiber for 10GBASE compliance with the optional fiber modules. Details on patch cord testing are given at the bottom of this article.

Should I use the DTX-GM2 instead of the DTX-MFM2?
The loss limits specified in IEEE 802.3ae are based on an LED source, not a VCSEL, even though the active equipment contains a VCSEL. Technically speaking, you should use the DTX-MFM2 to test multimode 10GBASE-S. However, there are people who feel this is incorrect. For that reason, we offer the DTX-GFM2 which contains an 850 nm VCSEL and 1310 nm FP laser source. Please look to your testing specification requirements.
 

You may asked for 10GBASE-SR or 10GBASE-SW testing, yet the DTX only has the 10GBASE-SR option. The R and W designation have no impact on the physical layer testing. The R implementation is for the LAN, the W implementation is for the WAN which has the capability to transmit and receive IEEE 802.3 MAC frames within the payload envelope of a SONET STS-192c/SDH VC-4-64c frame. Hence, in the DTX CableAnalyzer, you will only see 10GBASE-SR, LX4, L and E.

Suffixes:
    S: Short haul
    L: Long haul
    E: Extra long haul
 

10GBASE comes with severe length restrictions for multimode installations.

10GBASE-SR (Multimode 850 nm)

Most users are not aware of the severe length restrictions for 10GBASE-SR.

62.5/125 µm 160 MHz.km: 26 m

62.5/125 µm 200 MHz.km: 33 m

50/125 µm 500 MHz.km: 82 m

50/125 µm 2000 MHz.km: 300 m

Implementation of 10GBASE-SR can be a problem, since most customers look to the overall allowable loss:

62.5/125 µm 200 MHz.km: 2.4 dB

50/125 µm 500 MHz.km: 2.3 dB

50/125 µm 2000 MHz.km: 2.6 dB

and believe that if this is met, the link will support 10GBASE-SR. Not true.

There is another parameter called Modal Bandwidth (MBW) that affects the operation of 10GBASE-SR over multimode cable. MBW cannot be measured in the field. Therefore, this parameter is dealt with by defining a maximum length. Defining a maximum length assures the user that the MBW needed for 10GBASE-SR is met.

Another important aspect is how the IEEE defined the 2.6 dB maximum loss for 50/125 µm 2000 MHz.km. It is based on 300 meters of cable with a maximum  loss of 3.5 dB/km and two mated fiber connectors, each with a maximum loss of 0.75 dB. No splices.

Connector Loss = 0.75 dB

Cable Loss = 1.05 dB  (300 m @ 3.5 dB/km)

Connector Loss = 0.75 dB

Total Loss = 2.55 dB (Round up to 2.6 dB)

If your cable has a better fiber loss and/or you can guarantee a better connector loss, this may allow the use of splices. It does not permit you to extend the distance beyond 300 meters, unless the MBW of the cable is better than 2000 MHz.km. The limits in the DTX CableAnalyzer are taken from IEEE 802.3ae Table 52–10—10GBASE-SR link power budgets.

10GBASE-L/E (Singlemode)

There are two implementations for 10 Gigabit Ethernet over singlemode fiber optic cable:

10GBASE-L = 10 Gigabit Base Band Long Wavelength Serial (10 km @ 1310 nm)

10GBASE-X = 10 Gigabit Base Band Extra Long Wavelength Serial (30 km @ 1550 nm)

The DTX-SFM can be used up to 5 km in Smart Remote Mode, which covers all enterprise cabling defined in both TIA and ISO standards. Hence, the length limit assigned to 10GBASE-L/X within the DTX CableAnalyzer is 5 km. However, we know of customers successfully using the DTX-SFM beyond 5 km in Smart Remote Mode. If you need to increase this limit of 5 km, you can create a custom test limit. To do this in the DTX, rotate the dial to SETUP, select Fiber > Test Limit > Custom > Create. Change the Name from Custom Limit Name to the name of your choice, and then select Use Default Values From > Application > 10GBASE-L. You can now change the length to the limit you desire. Once done, press SAVE and ENTER to select your new custom limit. If you do not press ENTER after SAVE, your new limit will not be selected. Note that all custom limits have an asterisk (*) before and after the test limit name, to indicate a test outside of the default standards limits in the DTX CableAnalyzer.

 
Patch Cord Testing

This is no different to normal patch cord testing, except making sure that the fiber optic patch cable has the same MBW as the cable being installed. Marking the assembled patch cords with the appropriate MBW figure will reduce implementation errors.

You would use either the TIA568B Backbone MM or TIA568B Backbone SM ISP in Loop Back Mode with Bi-Directional testing enabled. Why? The patch cord should be tested in both directions. This means that the patch cord is reversed and tested a second time, since the mated connection to the input is not included in the measurement; this was reference out at the beginning. Your adapter count in the DTX should be set to 1 (One).

Mandrels are only required for multimode testing with the DTX-MFM. They are not needed when using either the DTX-GFM or DTX-SFM.