ospf-5----Page:8
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
|
Adjacencies Adjacencies are formed only between each DR/BDR router and its (Backup) Dependent Neighbors as selected by the CDS algorithm. The following enhancement greatly reduces the rate at which new adjacencies are formed, when the persistent version of the Essential CDS algorithm is used: Each DR/BDR router forms an adjacency with each (Backup) Dependent Neighbor that is a DR/BDR router. Each non-DR/BDR router selects two DR/BDR neighbor (one of which must be a DR), and forms adjacencies only with these two neighbors. These adjacencies are kept as long as both are DR/BDR neighbors and one of them is a DR. The two selected DR/BDR neighbors are included in the DR and BDR fields of each Hello, as in legacy OSPF. |