At a site, NE80 is at VRP3.10-2xxx. An interface repeating up/down results in route flaps, and the MPU and LPU in some network segments have not been synchronized, blocking the forwarding services.
1. Execute display ip routing-table statistics command to check the number of valid routes on MPU.
2. Use en_ command to enter diagnosis mode, and execute display table slot number 7/8 (7 represents for the routes of which the mask is more than 16, and 8 represents for that of which the mask is less than 16) command, and then press ctrl+c to stop the checkup for the total number of valid routes on interface board.
3. The number of valid routes at MPU is similar to that on interface board, not absolutely the same, if only the display table command on each interface board shows the same result at slot 7. Generally, the mask of most routes is more than 16.
4. If the number of routes on an interface board is less than that on the others , it means that some routes may be lost in update, so it needs to update again.
If the number of routes is very large, and the message traffic over communication channel between MPU and LPU greaten, route flaps will result in that route update message is lost, and the MPU and LPU cannot be synchronized, blocking the forwarding of packets.