VPN Traffic Is Unavailable Because Parameters of the NE40 and the OSN 1500 Are Different

The networking diagram where the problem occurs is as follows:

After the configuration is complete, NE40-1 and NE40-2 are connected to laptops. Then, use Bricks (a simple traffic testing software) to test the traffic. It is found that no traffic reaches the peer. 

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1. Check the physical connection, and you can find that all electrical and optical interfaces are Up.

5. Check the traffic testing method. It is found that the length of the packet sent by Bricks is 32767, which exceeds the MTU of the transmission device. As a result, the traffic is discarded. Modify the length of the packet sent by Bricks to 1400, and the problem is solved. The peer receives traffic that is 4.1 Mbit/s, which accords with the design requirements. 

1. The physical connection fails.

5. The traffic testing method is incorrect. 

1. When the NE40 uses the GE WAN board to connect the OSN, note the negotiation.

3. A transmission device has its MTU on the link layer. A packet is not fragmented when the length of the packet exceeds the MTU. Instead, the packet is discarded. Such factor should be fully considered in the design.