Nbr is Master Priority

Hi,

The Open Shortest Path First (OSPF) protocol, developed by the Internet Engineering Task Force (IETF), is a link-state Interior Gateway Protocol (IGP). At present, OSPF Version 2, defined in RFC 2328, is intended for IPv4, and OSPF Version 3, defined in RFC 2740, is intended for IPv6.

Two OSPF-enabled routers connected by a common network and in the same OSPF area that form a relationship are OSPF neighbors. The connection between these routers can be through a common broadcast domain or by a point-to-point connection. This connection is made through the exchange of hello OSPF protocol packets.

The election of the master slave relationship is mainly to determine the DBD sequence number. This sequence number can ensure the orderly and reliable transmission of DBD messages.

OSPF Neighbor States

To exchange routing information on an OSPF network, neighbor Routers must establish adjacencies. The differences between neighbor relationships and adjacencies are described as follows:

• Neighbor relationship: After the local Router starts, it uses an OSPF interface to send a Hello packet to the remote Router. After the remote Router receives the packet, it checks whether the parameters carried in the packet are consistent with its own parameters. If the parameters carried in the packet are consistent with its own parameters, the remote Router establishes a neighbor relationship with the local Router.

• Adjacency: After the local and remote Routers establish a neighbor relationship, they exchange DD packets and LSAs to establish an adjacency.

OSPF has eight neighbor states: Down, Attempt, Init, 2-way, Exstart, Exchange, Loading, and Full. Down, 2-way, and Full are stable states. Attempt, Init, Exstart, Exchange, and Loading are unstable states, which last only several minutes. Figure 6-3 shows the eight neighbor states.

For more information:

https://info.support.huawei.com/network/ptmngsys/Web/tsrev_ar/en/content/ar/17_edesk_ospf_peer_status_abnormal/edesk_ospf_peer_status_abnormal_edesk001.html

https://support.huawei.com/enterprise/en/doc/EDOC1100058422/e2fdfced/ospf-fundamentals

Hi MandelPhile,

Do you mean the Neighbors field in OSPF Hello packets? 

The Neighbors field specifies the router ID of the neighbor router. The DR priority is first compared with that of the BDR. The DR with the highest DR priority wins. If the priorities are the same, the router with a larger router ID wins. The Rtr Rri field indicates the DR priority. The default value is 1. If the Rtr Rri field is 0, it indicates that the DR is not elected. You can run the ospf dr-priority command to configure the DR priority on an interface.