1. Network topology: NE80-1------NE20E-----NE80-2
2. NE80-1 and NE80-2 run as PEs and the NE20E as the P device. NE80-1 connects the NE20E through 155M pos link. The management port of the NE20E connects NE80-2 through the Ethernet.
3. Ping NE80-2 from NE80-1 through VPN instances. The packets with a maximum of 1506 bytes can be transmitted.
Ping NE80-1 from NE80-2 through VPN instances. Long packets can be transmitted.
1. Run the debug ip icmp command on NE80-1 and NE80-2. When you ping NE80-2 from NE80-1, no ICMP request packets are received on NE80-2.
2. When you ping NE80-1 from NE80-2 through long packets, ICMP request packets are received on NE80-1. NE80-2 responds ICMP reply packets.
3. Based on the preceding analysis, packets are discarded from NE80-1 to NE80-2.
4. Header capture on the interfaces of NE80-1, NE20E, and NE80-2. The NE20E receives packets of NE80-1, but it does not forward packets to NE80-2. Why does the NE20E discard packet?
5. Consult with R&D. The management port on the RPU of the NE20E can receive packets with the maximum of 1552 bytes. The interface board has no restriction on packet length. Long packets with 4470 bytes can be transmitted on the POS interface between the NE80 and NE20E. After they are transmitted to the NE20E, they fail to pass because of the restriction of the management port. Only packets within 1506 bytes (1552 = 1506 + 20 + 8 + 14 + 4) can pass. There is no problem on the interface board.
1. The NE80 or NE20E fails.
2. Links between devices fail.
Do not carry services on the management port when the NE20E is used.