Shulou(Shulou.com)06/01 Report--

Previously, the customer headquarters and the branch were connected through a single-mode fiber transceiver.

In order to achieve the purpose of redundant backup, the headquarters and branch offices added another link to form a double link. However, during the implementation, it is found that the newly added link can be connected normally through the 10-gigabit single-mode module, and the data transmission is normal, while the original link is blocked at both ends after connected to the 10-gigabit module! It used to be easy to use, but now it doesn't work, we put our eyes on that pair of 10-gigabit modules, after all, what users purchase is O modules, not the original factory, so it is inevitable that there will be problems.

After negotiation with the manufacturer, two pairs of modules were sent again, but after the replacement, it was found that the link was still blocked! I can't believe it doesn't work! In order to further determine whether it is the problem of the module, we connect this pair of modules to the useful link and find that the two ends are connected! Is it possible that the problem lies in that link?

In order to find out the problem, I came to the scene with an optical power meter. I was surprised by the test. The result is shown in the following figure:

According to the detailed parameters of the module, we find that:

Product

Type

Transmit Power (dBm) *

Receive Power (dBm) *

Transmit and Receive Wavelength Range (nm)

Maximum

Minimum

Maximum

Minimum

Transmit

Receive

Cisco X2-10GB-SR

10GBASE-SR 850 nm MMF

-1.2 million *

-7.3

-1.0

-9.9

840 to 860

Cisco X2-10GB-LRM

10GBASE-LRM 1310 nm MMF

0.5

-6.5

0.5

-8.4 (in average)

And-6. 4 (in OMA) *

1260 to 1355

Cisco X2-10GB-LX4

10GBASE-LX4 WWDM 1300 nm MMF

-0.5 per lane

-6.75 per lane in OMA

-0.5 per lane

-14.25 per lane in OMA

Four lanes; overall range: 1269 to 1356

Cisco X2-10GB-LR

10GBASE-LR 1310 nm SMF

0.5

-8.2

0.5

-14.4

1260 to 1355

1260 to 1565, please.

Cisco X2-10GB-ER

10GBASE-ER 1550 nm SMF

4.0

-4.7

-1.0

-15.8

1530 to 1565

1260 to 1565, please.

Comparing the test results with the minimum value of receive power in the table, it is found that the optical attenuation of the link has exceeded the received minimum value, so the link cannot be connected to the module! But why use optical transceivers to get through? The reason is still light attenuation, as follows:

"single-mode transceivers can cover a range from 20 km to 120 km. It should be pointed out that due to the different transmission distance, the transmission power, reception sensitivity and wavelength of the optical fiber transceiver itself will be different. For example, the transmitting power of 20km optical fiber transceiver is generally between-15~-7dB, the receiving sensitivity is-30dB, using the wavelength of 1310nm, while the transmitting power of 120km optical fiber transceiver is mostly between-5~0dB, the receiving sensitivity is-38dB, using the wavelength of 1550nm. "

After the operator optimizes the link, after connecting the module, the link is connected! At this point, the problem is solved!

Conclusion: in peacetime, we must pay attention to the use of the environment, and when there are problems, we must go through careful testing!

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