Using default routes learned from OSPF via adjacent switches or own switch def routes

[getaway51]

Hi ,

Both my core switches has default routes going to routers. How can I check if the core switches is using its own default route or def route OSPF learned from adjacent core switches? 

[CHYMER]

Hi mr,

You should use command below

Show ip route 0.0.0.0/0

If it is static route => route 0.0.0.0/0 is owner of this core switch

if it is route learn via ospf => check next hop and you will know default route learn from (maybe learn from router of other core switch) ?

Thanks and Brgs,

[Seb Rupik]

Hi there,

If the 'own switch default route' is a statically configured route defined by specifying a next-hop IP (instead of just an exit interface) then providing the next-hop is reachable via an interface which is up/up, then the static route would be visible in the routing table~:

sh ip route static

A route learned via OSPF would be displayed with the command:

sh ip route ospf

If both routes were valid, then keep in mind that the static route would have a lower Administrative Distance than the OSPF route. Therefore the static route would always take precedence over the OSPF route.

cheers,

Seb.

[paul driver]

Hello

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@getaway51 wrote:

Both my core switches has default routes going to routers. How can I check if the core switches is using its own default route or def route OSPF learned from adjacent core switches? 

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The core switches will use their own defaults and not the advertised ospf ones due to the lower administrative distance value of the core switches defaults.

[getaway51]

Can I see the "lower administrative distance value" when i saw ip route 0.0.0.0/0?

Does this means i will see two def route 0.0.0.0/0, each with different preference?

[Seb Rupik]

show ip route

will give output like:

S*     0.0.0.0/0 [1/0] via 192.168.1.1

The element [1/0]   indicates an AD of 1 and a metric of 0 

Only the route with the lowest AD will be installed in the routing table.

cheers,

Seb.