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10GE Multi-mode Interface on NE40E Failed to Become Up

Publication Date:  2013-10-08 Views:  52 Downloads:  0
Issue Description
A 10GE multi-mode interface on an NE40E running V300R003C02B697 was interconnected with another device through corridor multi-mode optical fibers. The receive power and transmit power of the interface were normal but the interfaces failed to become up.
Handling Process

Possible causes include:

1. The optical module or board was faulty.

2. Interconnection optical fibers and corridor fibers were faulty.

3. The distance between the NE40E and the interconnected device was greater than that the optical module supported.

4. An improper type of optical fibers were used.

Huawei performed the following operations to address the problem:

1. Switched the faulty interface and an up interface on the NE40E. The faulty interface became up and the originally up interface became down. Therefore, the problem was not caused by a fault on the optical module or board.

2. Tested the transmit and receive power on the interconnected interfaces. The power was normal. Therefore, the problem was not caused by a fault on the interconnection or corridor optical fibers.

3. Found the distance between the interconnected devices was about 180 m, within 300 m that the optical module supported. 

4. Checked the optical fibers and found that the device used 50 um diameter jumpers (OM3) and the corridor optical fibers used 62.5 um diameter jumpers (OM1). The 10GE optical module required a dispersion tolerance of 400ps/nm to 800ps/nm and therefore OM3 multi-mode optical fibers must be used.
Root Cause
Incorrect jumpers were used and therefore the dispersion tolerances were different.
Solution
Changed the interface to work in single-mode interconnection mode.
Suggestions
10GE multi-mode optical modules have high requirements on dispersion. The 10GE 850 nm multi-mode optical modules support transmission over a distance of 300 m only if only OM3 optical fibers were used for interconnection. If any OM1 optical fibers were used, the actual supported distance was about 80 m.

END