[c-nsp] OSPF link costs

[Robert Blayzor]

Is there a way using OSPF to have a router set the cost or preference of
a single link?  I guess I'm thinking much in the way BGP prepending
works with the destination router setting the cost or metric the way the
neighboring routers would see it.  Say for example you had the following
network:

+----+        +----+
!    !        !    !
! R1 !---GE---! R2 !
!    !        !    !
+----+        +----+
  !              !
  !              !
  GE             GE
  !              !
  !              !
+----+        +----+
!    !        !    !
! S1 !\      /! S2 !
!    ! \    / !    !
+----+  \  /  +----+
  !      \/      !
  !      /\      !
  GE    /  \     FE
  !    GE  GE    !
  !   /      \   !
+----+        +----+
!    !        !    !
! R3 !        ! R4 !
!    !        !    !
+----+        +----+


Assume R1 & R2 are routers, S1 & S2 are subnets/SVI's on switches and R3
& R4 are routers.  Focusing on router R4; it is very easy to set the
cost on the link facing the SVI on S2 to a high cost where it's never
used unless it's the only link.  R3 would be seen as equal cost in both
directions of the network, which is fine.  But since there is only one
interface/SVI on S2 how is it possible to NOT use the FE link to R4
since the cost of the SVI interface would be the same for all links in
the subnet?  Is there a way on R4 to set a cost or metric so that
upstream routes for the FE link are at a higher cost?  The best way I
can think of this is sort of link BGP pre-pending and having the
destination router set the cost of the link to the network.

-- 
Robert Blayzor, BOFH
INOC, LLC
rblayzor\@(inoc.net|gmail.com)
PGP: 0x66F90BFC @ http://pgp.mit.edu
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