OSPF Example Question

adeel32adeel32 Member Posts: 27 ■□□□□□□□□□

Can anyone guide me what is the difference between

set area 10 stub default metric 10
set area 10 stub default metric 15

As i am configuring stub area in OSPF reference page 183 on JNCIP book

R3 and R4 are my ABR for area 10. When i use default metric 15 in R3 and default metric 10 in R4, i can see only R1 metric is 12 for default router and R2 metric is 11 for default.

In my opinion it is required only for load balance the routes while keeping both default metric equal. Am i right?

Adeel Ahmed

Adeel Ahmed


  • hoogen82hoogen82 Member Posts: 272
    Hi Adeel,

    The difference is the metric.. You should not advertise different metric on your ABR.. this solution of putting 15 on R3 and 10 on R4 will result in all routers in that area to prefer R4 to go out of that area.. Yes.if the question asks you to send out all traffic in this area through R4 this would be a good solution. But the book or the case study here doesn't ask for that..

    R1 uses metric of 12 because R1-R2-R4... which is 1+1+10 = 12..
    R2 uses metric of 11 because R2-R4.. which is 1+10 = 11..

    If you had used metric of 10 on both R3 and R4..
    R1 would have preferred a route through R3 with a metric of 11
    R2 would have had two paths R3 and R4 with a metric of 11

    IS-IS Sleeps.
    BGP peers are quiet.
    Something must be wrong.
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