From: xprtofnet (xprtofnet@yahoo.com)
Date: Sun Apr 23 2006 - 14:09:08 GMT-3
VL is a virtual interface in area 0. it has no cost to
it since you can not route over it.
see below
R3#sho ip os virtual-links
Virtual Link OSPF_VL0 to router 0.0.0.2 is up
Run as demand circuit
DoNotAge LSA allowed.
Transit area 1, via interface Ethernet1/0, Cost of
using 10 <<<---
the vl is using e1/0 as its interface and using its
cost.
m2c..
--- Reinhold Fischer <Reinhold.Fischer@gmx.net> wrote:
> Hi Victor,
>
> this is really an interesting question that i never
> thought about.
> The following is just my understanding and i could
> be wrong:
>
> The virtual link is not like a tunnel where packets
> are forwarded through.
> It is just a definition, that (simplified) says that
> two not directly
> connected routers should exchange ospf information
> by means of ip unicast
> packets. That packets follow a certain way through
> the transit area
> according to the ospf metrics of the links in that
> transit area. The
> metric that you see on the virtual link and that is
> visible to the
> backbone area is the metric of this best way through
> the transit area.
> The separate link metrics and details of the transit
> area are not known
> to the backbone area.
>
> I think there is no reason to be able to change the
> cost of the VL directly.
> The VL is just a simplified representation of the
> cost to go through the
> transit area used by the SPF calculation of the
> backbone area.
>
> Anyone with a better explanation? I've read rfc2328
> and Routing TCPIP
> Vol1 but found no good explanation. Eventually the
> John Moy OSPF book
> has a better information, but i do not have this
> book...
>
> regards
>
> reinhold
>
>
> On Sat, Apr 22, 2006 at 04:52:15PM -0400, Victor
> Cappuccio wrote:
> > Hello All,
> >
> > Does anyone know how to modify the OSPF Virtual
> Link Cost?
> > I been searching in cisco/google/router but with
> no luck (seems to me
> > logic to modify a Cost to a Virtual Link), and yes
> we can lower the cost
> > of other interfaces, but why not with the VL?
> >
> > Thanks
> > Victor.
>
>
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