Context
OSPF has eight neighbor states: Down, Attempt, Init, 2-way, Exstart, Exchange, Loading, and Full.
- Down: indicates that a router has not received any Hello packets from its neighbors within a neighbor dead interval.
- Attempt: occurs only in an NBMA network, indicating that the router has not received any Hello packets from its neighbors after the dead interval expires. The router still sends Hello packets to its neighbors at the poll interval.
- Init: indicates that the router receives Hello packets.
- 2-way: indicates that the router receives Hello packets that contain its router ID. If the router does not need to establish adjacencies with its neighbor, the OSPF neighbor status remains 2-way. Otherwise, the neighbor status enters the Exstart state.
- Exstart: indicates that the router and its neighbor begin to negotiate a master/slave relationship and determine sequence numbers of DD packets.
- Exchange: indicates that the router and its neighbor begin to exchange DD packets after the master/slave relationship negotiation is complete.
- Loading: indicates that the router and its neighbor finish exchanging DD packets.
- Full: indicates that the LSR retransmission list is empty.
If the OSPF neighbor status remains Init, two possible causes exist:
- A broadcast interface is simulated as a P2P interface.
- The peer device cannot receive Hello packets from the local device.
Procedure
- A broadcast interface is simulated as a P2P interface.
In Figure 1, Ethernet interfaces of RT1, RT2, and RT3 reside on the same broadcast network and have the ospf network-type p2p command configured. As defined in OSPF, only one OSPF neighbor relationship can be established on a P2P interface, and Hello packets are multicast packets and will be transmitted throughout the entire broadcast network.
RT1 receives from RT2 a Hello packet that does not carry RT1 information and begins to establish an OSPF neighbor relationship with RT2, while the neighbor status is Init. RT1 keeps waiting to receive such a Hello packet from RT2, but RT2 has established an OSPF neighbor relationship with RT3 and does not send the Hello packet to RT1. As a result, RT2's neighbor status on RT1 remains Init.
Figure 1 Failure to establish an OSPF neighbor relationship on a P2P interface in a broadcast network
This fault is caused by incorrect configurations. To rectify the fault, delete the ospf network-type p2p command configuration from this interface.
# Delete the OSPF network type of GE2/0/0. Similarly, delete the OSPF network types of GE2/0/1 and GE1/0/0.
<Huawei> system-view [Huawei] interface GigabitEthernet 2/0/0 [Huawei-GigabitEthernet2/0/0] undo ospf network-type [Huawei-Vlanif1] return <Huawei>
- The peer device cannot receive Hello packets from the local device.
Rectify the link fault and peer device fault. If there are intermediate devices between the local and peer devices, check whether the intermediate devices allow OSPF packets to pass through.
Run the debugging ospf event and debugging ospf packet hello commands on the two devices to enable debugging of Hello packet transmission. To disable Hello packet transmission, run the undo debugging ospf event and undo debugging ospf packet hello commands.
# Enable debugging of the OSPF module. After debugging is enabled, a large amount of debugging information will be displayed. Therefore, confirm the action before enabling debugging.
<Huawei> debugging ospf event <Huawei> debugging ospf packet hello <Huawei> terminal debugging <Huawei> terminal monitor
# Disable OSPF debugging.
<Huawei> undo debugging ospf event <Huawei> undo debugging ospf packet hello