When NE40E 2.5G POS interface connects with M320 of J corporation, the physical state is normal. After IP address is configured, the protocol state is normal. It cannot be pinged.
C2 byte of NE40E 2.5G POS interface is configured as 0xCF. Configuration command: flag c2 207
The problem can be solved.
1. Default configuration of different router corporation is not the same. NE40E 2.5G POS is under PPP mode under default and C2 byte is 0x10; M320 of J corporation is under HDLC mode under default and C2 byte is 0xCF.
2. There is no transmission device between NE40E and M320. Keep C2 byte as the same.
3. Regarding that there is transmission device between NE40E and M320, the configuration of C2 byte should be taken into consideration. the default C2 byte of transmission device is 2, it indicates that it is voice service.