Reason legend in show ip ospf statistics

It provides information about how frequently a router is executing the SFP algorithm.This command also shows when the SPF algorithm last ran and is recommended as the first troubleshooting step for link-state advertisement (LSA) flapping.



Show ip ospf statistics output show below :

R1#sho ip ospf sta

            OSPF Router with ID (192.168.0.1) (Process ID 1)

  Area 0: SPF algorithm executed 3 times

  Summary OSPF SPF statistic

  SPF calculation time

Delta T   Intra D-Intra Summ    D-Summ  Ext     D-Ext   Total   Reason

7w0d   0        0       0       0       0       0       0       R, N,

7w0d   0        0       0       0       0       0       0       R, N, X

7w0d   0        0       0       0       0       0       0       N, X

7w0d   0        0       0       0       0       0       0       R,

7w0d   0        0       0       0       0       0       0       R, N, X

7w0d   0        0       0       0       0       0       0       R,

7w0d   0        0       0       0       0       0       0       R,

7w0d   0        0       0       0       0       0       0       R, N, X

7w0d   0        0       0       0       0       0       0       R, N,

5w0d   0        0       0       0       0       0       0       R, N, SN, SA, X

R1#

Record of reasons causing SPF to be executed:

    N—A change in a network LSA (type 2) has occurred.
    R—A change in a router LSA (type 1) has occurred.
    SA—A change in a Summary autonomous system boundary router (ASBR) (SA) LSA has occurred.
    SN—A change in a Summary Network (SN) LSA has occurred.
    X—A change in an External Type-7 (X7) LSA has occurred.