The Differences Between MODF and ODF

Problems in the use of traditional ODF

Designers in the transmission profession are familiar with Optical Distribution Frame. The reason why ODF pigtails are placed chaotically is that the utilization rate of these ODF terminals is very low. If the ODF terminal usage rate is higher than 50%, it will be even more chaotic.

 

Causes of ODF fiber jump disorder

There are two main reasons for the chaos of ODF fiber jumper deployment: product design defects and engineering design deviations.

 

1. Defects in product design

The current mainstream ODF size is 2200 × 840 × 300 (height × width × depth, mm), and the capacity is 648 cores. The space on the left side of the rack body is the disc fiber unit, and the excess length of the fiber jumper is reserved here. This space is also the only channel for fiber jumpers to be placed. Whether fiber jumpers in or between racks (from other devices or ODFs to this ODF) must be deployed through this channel. If the ODF rack has 2/3 of the capacity for intra-rack connection (one fiber jumper for every two ports) and 1/3 of the capacity for inter-rack connection, a maximum of 432 fiber jumpers will be deployed.

 

2. Engineering Design deviation

According to the size of ODF, the maximum length of the fiber jumper in the rack should not exceed 3m, 70% of the fiber jumper length should not exceed 2.5m, 40% of the fiber jumper length should not exceed 2.0m, and even a small amount of fiber jumper length only needs 1.5 m is enough. However, the fiber jumpers listed in our design file are basically 3.0m in length, and the average length of each fiber jumper exceeds 0.5m. The diameter of the fiber jumper is 2.0mm or 1.2mm, and the performance indicators meet the requirements of use, but almost all the fiber jumpers of the design configuration are 2.0mm in diameter.

 

The design concept of MODF

The design of MODF adopts the design concept of the cable main distribution frame (MDF), and the frame body is divided into the line side and the equipment side. The core end of the external optical fiber cable is on the line side, and the port of the device is connected to the optical fiber on the device side. The fiber jumper is jumped from the corresponding device port on the device side to the corresponding core of the external optical fiber cable. MODF disk fiber units are installed on both sides of the rack, which is also the channel where fiber jumpers are placed from the device side to the line side. However, no matter how large the capacity of the disc fiber unit is, it can't meet the excess length requirement of several meters of each fiber jumper in the design. Therefore, in order to respond to those sloppy designers, MODF has designed a supporting fiber storage rack. When the MODF contains multiple racks, in order to facilitate the deployment of fiber jumpers between the racks, a fiber jumper horizontal channel is provided on one side (equipment side) or both sides of the MODF.

 

The main types of MODF

Considering the welding position of the external optical cable, MODF is mainly divided into: final fusion separation type and final fusion integration type.

 

1. Final melting separation type

The MODF frame of the final melting separation type is composed of two types of frames: a fusion frame and a terminal frame. The external optical fiber cable is welded on the fusion splice frame and ends on the line side of the terminal frame. The final melt separation type MODF is mainly used for the station with a larger final capacity, such as the core node. However, the setting of the welding frame and the terminal frame has a certain proportional relationship, and the expansion is limited. The advantage is that the terminal frame does not need to be equipped with a lightning protection ground bar.

 

2.Final melting integrated type

The final fusion-integrated MODF is the same as the ODF. Each rack contains an optical cable end fusion unit, which is divided into A type, B type and C type. The structure of each model is similar.

 

The design concept of MODF is not to increase the capacity density of ODF, but to facilitate fiber jumper management. But we still need to pay attention to 2 points in the design: 1. Try to configure the appropriate length of fiber jumper as needed, and don't leave too much extra length. 2. Try to use φ1.2mm fiber jumper instead of φ2.0mm fiber jumper.

 

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