Routing

Hi Guys,

Had a quick query that's more out of curiosity than anything.

Currently studying between the JNCIA and JNCIS level and it's noted that by default, there is a default route installed by the Kernel on your JUNOS device.

This is over-ridden if you create your own static default route or if it's learnt by routing protocol (i.e. a user route).

However, it's also stated that Kernel-installed routes have a default preference of 40. So what happens when I create a static route with a preference of 41, either with the preference command under a the specific route or modifying the defaults of static routes to have a preference of 41; knowing that the Kernel installs a "Reject" default route by default?

Would the Reject take precedence, or would the user-installed route still become active? If it's the latter, is this because the preference of 40 associated with the "Kernel" routing protocol not related to the default Kernel-installed default reject route?

Thanks in advance,

Kindest Regards, 

Andrey Leo

PS

I should probably just try this, but unsure if the JUNOSPHERE images quite follow the same default rules as you're taught in the books. And even if does show me the answer, I wouldn't understand it.

if you create your own static default route, the sytem defined entry in the forwarding table is not overridden as you can clearly see from the output show route forwarding-table. Both default entires remain.

The user defined static route always takes precedence over the system defined default route regardless of the preference you assign to it.

I guess this is just by design, like how Local and Direct routes are preferred over all other routes.

Thank you 🙂