OSPF Type-3 default route LSA metric

[Sam-CCNP]

Hi,

Does anyone know if there is a way to change the metric of a

Type-3 default route LSA?

The purpose is to influence the exit point for traffic in a totally stubby area with two ABRs.

Thanks.

Sam

[M02@rt37]

Hello @Sam-CCNP,

To influence the exit point for traffic, you can manipulate the OSPF cost on the interface connecting to the totally stubby area to indirectly influence the preferred exit point.

[Sam-CCNP]

Hi, thanks for responding.

I think maybe I worded my question poorly. It's the traffic exiting the stub area i want to influence, not entering.

And as it's a tsa, traffic uses the

 type 3 default route

, which is the metric I want to influence.

Thanks. Sam

[Blue_Bird]

You can change with following commands.

(config)#router ospf <process>
(config-router)#default-information originate [always] [metric <metric>] [metric-type {1|2}]

Thanks

[Harold Ritter]

Hi @Blue_Bird ,

This is the command you would enter if you wanted to originated the

default route 

as an external

ospf route

. In a totally stubby area, the

default route

is already injected as an

inter area route

. This is the one for which @Sam-CCNP wants to change the metric.

Regards,

[Harold Ritter · Accepted solution]

Hi @Sam-CCNP ,

You can use the following command command on the ABR to set the cost value on the default injected in the stub area:

router ospf <process-id>

area <x> default-cost <cost>

Regards,

[Sam-CCNP]

Thanks. Thats the one. Brain got lazy and gave up quickly.

As an aside, what if I left one ABR configured as a stub but the other ABR as a totally stuby area by adding no-summary? That would result in the more specific inter-area routes being propagated into the area from one router, making it the preferred exit point.

I know it sounds strange, but I'm studying for my CCIE lab, whose solutions sometimes do not reflect reality (I've heard).

[paul driver · Accepted solution]

Hello
If you which to influence which ABR is used, you could set a maximum metric  to the least preferred

rtr
router opsf x
max-metric router-lsa summary-lsa

[Sam-CCNP]

I just looked up that command and applied it to the ABR in my lab, it worked so I'll try to remember that one too. Thanks!