The start of the JNCIS-ENT

What I learnt last night – instead of overloading with reading at night and falling asleep with my head in a book. I am taking a different tact for reading – one hour only. I was talking with someone on the Cisco CLN and they were saying that they only read for one hour per night. This allows them not to become overloaded with information, they also find that they can remember more and not have to re-read again later. I thought I would give this a try!

So last night upon starting the reading for the JNCIS-ENT – I sat down and this is one of the things I learnt, which I thought was very cool. It also happen that while doing one of the mock exams on Junipers website for this exam they covered this in a question.

The qualified-next-hop option allows independent preferences for static routes to the same destination.

If this was Cisco this would be called a floating static route. You create a static route to the destination (by default with Juniper the next hop IP address of a static route must be reachable using a direct route) if that next hop become unavailable then the “qualified-next-hop” is used as the next hop.

[edit routing-options]
bigevil@R11# show
static {
route 0.0.0.0/0 {
next-hop 192.30.25.1;
qualified-next-hop 192.30.25.5 {
preference 8;
}
}
}

The 192.30.25.1 next hop assumes the default static route preference of 5, while the qualified 192.30.25.5 next hop uses the defined route preference of 8. All traffic using this static route uses the 192.30.25.1 next hop unless it becomes unavailable. If the 192.30.25.1 next hop becomes unavailable, the default static route will then use the 192.30.25.5 next hop.

Another cool feature in the [edit routing-options static] configuration hierarchy, the defaults section can encompass static route options. Any options configured within this section are applied to all static routes on the device.

With this in mind how would the following work?

[edit routing-options]
bigevil@R11# show
static {
defaults {
preference 180;
}
route 0.0.0.0/0 {
next-hop 192.30.25.1;
qualified-next-hop 192.30.25.5 {
preference 8;
}
}
}

The default for preference for static routes has become 180 – therefore 192.30.25.1 has a route preference of 180 instead of 5. The 192.30.25.5 has route preference of 8 which is explicitly set. Thus the next hop is 192.30.25.5 – sweet.

BE.

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~ by bigevil on February 7, 2012.