OSPFv2 VS OSPFv3 route selection

edited June 2017 in Foundation Lab 3

Hello ,

while i am doing foundation LAB 3, after the redistribution section on R6 and R 7 betwee OSPFV3 and OSPFV2 then redistribute RIP on R1 .

i notice that R9 RIP route ( ) is being preferred through R3 ( DMVPN HUB ) with forward metric 2000 rather than R 6 where the forward metric is 1 .

although both routes are of E2 type ?? why is that

Also on R6 , the route to is through ospfv3 as E2 , although the same route is learned through R1 as IA

can anyone help??



  • Hello Folks,

    I tried to make a small topology which have both ospfv2 and ospfv3 , i find out that the route selection depends on which routing protocol route is installed first .


  • Hi, since routing source is different (ospfv2 and ospfv3),AD is used to prefer one route over another.Both have 110 AD (which is default too) then older route is stored in RIB.
    (Reference: cisco live pdf : http://d2zmdbbm9feqrf.cloudfront.net/2010/usa/pdf/BRKARC-2350.pdf)

    Keep in mind that between the different processes of the same routing protocol process ID is also used as tie breaker. (For OSPFv2 lower process ID,for EIGRP lower AS number).

    Now let's discuss the 2nd question: is external network for OSPFv3 so R6 sees it as external type. (E) is inter-area network for OSPFv2 so R6 sees it as inter-area type (O IA)

    Best regards,

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