Configuring an Interface to Fill in a DD Packet with the Interface MTU

To improve compatibility with a non-Huawei device, an OSPF-enabled Huawei device adds the MTU 0 in DD packets to be sent and does not check the MTUs in received DD packets, allowing an OSPF neighbor relationship to be set up even if the two ends have different MTU settings.

However, under the default configuration, the non-Huawei device may discard an OSPF packet received from the Huawei device if the packet's actual MTU is greater than the MTU of the non-Huawei device. If the discarded packet is an LSU, an OSPF neighbor relationship can still be set up, but the route carried in the LSU fails to be learned, causing service interruptions.

To resolve this issue, run the ospf mtu-enable command to configure an interface to add the actual MTU in DD packets to be sent and check whether the MTU in a received DD packet is greater than the local MTU. If the interface MTU settings of the local and remote ends are different, an OSPF neighbor relationship cannot enter the Full state. In this manner, MTU inconsistency can then be identified in time.

Setting the MTU in a DD packet will have the neighbor relationship reestablished.