From: Wei Man (mandraw1@xxxxxxxxx)
Date: Sun Jul 01 2001 - 10:31:10 GMT-3
>From my Lab, ospf cost R3 back to back connection with
R1 is greater than from R3-R2-R1.
so in theory, it should use R3-R2-R1 . In my lab
it is still using R3-R1 back to back connection.
According to OSPF Network Design Solution
page 235 (Controlling Inter-Area Traffic)
One of the condition of OSPF Traffic selection is
"Use the ABR closest to the destination of traffic"
so which one does have more priority ?
"Use the ABR closest to the destination of traffic" or
"total ospf cost to destination"
--- Ravi <s_ravichandran@hotmail.com> wrote:
> It depends on the total cost from host A to R4. OSPF
> will choose the route
> with lowest cost. So in your case R4 has two route
> to host A. Now ospf will
> check the cost and decide the best route. If it has
> equal cost then it will
> do load balance. You can also manipulate the cost of
> a link and choose the
> route that you would prefer.
>
> Regards,
> Ravi
> ----- Original Message -----
> From: Wei Man <mandraw1@yahoo.com>
> To: <ccielab@groupstudy.com>
> Sent: Sunday, July 01, 2001 7:41 AM
> Subject: OSPF Concept Question
>
>
> > I have question regarding how OSPF behave
> > in selecting route
> >
> >
> > A--R0--R1----R2----R3---R4
> > \ /
> > ----------
> > Where R1 is connected back to back with R2
> > using Serial 0
> > and R1 is connected back to back with R3 using
> > Serial 1
> >
> > A is host connected to R0 and is in Area 0
> > Link R0 to R1 , OSPF Area 0
> > Link R1 to R2 , OSPF Area 1
> > Link R2 to R3, OSPF Area 2
> > Link R3 to R4, OSPF Area 2
> > Link R1 to R3, OSPF Area 3
> >
> > There is virtual link to between R0-R1 to R2-R3
> > using Area 1 as transit area
> >
> > When R4 try to reach A, which Route R4 will use
> > Is R4-R3-R2(Virtual Link)-R1-R0-A or
> > R4-R3-R1-A ?
> > Can somebody explain to me how route selection
> > in ospf works in this case ?
> >
> > Thanks in advance
> >
> >
> >
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