实验拓扑图
![0](https://img2020.cnblogs.com/blog/1356910/202107/1356910-20210716225102292-1210628528.jpg)
查看指定端口网络类型:DR是自己,BDR没有
![0](https://img2020.cnblogs.com/blog/1356910/202107/1356910-20210716225102276-539012794.jpg)
再配置R2,完成后显示
![0](https://img2020.cnblogs.com/blog/1356910/202107/1356910-20210716225102335-7018055.jpg)
抓包显示DR和BDR都有了,先入为主
![0](https://img2020.cnblogs.com/blog/1356910/202107/1356910-20210716225102471-2130823886.jpg)
添加进R3,按拓扑命令配置
抓包显示:
![0](https://img2020.cnblogs.com/blog/1356910/202107/1356910-20210716225102496-1770548755.jpg)
![0](https://img2020.cnblogs.com/blog/1356910/202107/1356910-20210716225102299-1645381691.jpg)
![0](https://img2020.cnblogs.com/blog/1356910/202107/1356910-20210716225102317-812126757.jpg)
按照拓扑图配置R4,抓包显示
![0](https://img2020.cnblogs.com/blog/1356910/202107/1356910-20210716225102329-243603146.jpg)
在R4查看邻居
![0](https://img2020.cnblogs.com/blog/1356910/202107/1356910-20210716225102470-644311095.jpg)
DR、BDR、DRothers之间都保持邻接关系 (Full)
DRthers之间都保持邻居关系(Two-Way)
有变化时向组播地址224.0.0.6,DR和BDR监听这一组播地址
![0](https://img2020.cnblogs.com/blog/1356910/202107/1356910-20210716225102254-534601178.jpg)
1.0.0.3发给224.0.0.6,DR收到后发给所有人,2、4再进行确认
![0](https://img2020.cnblogs.com/blog/1356910/202107/1356910-20210716225102260-1450490626.jpg)
重启ospf ,重新分配
![0](https://img2020.cnblogs.com/blog/1356910/202107/1356910-20210716225102495-1785191631.jpg)