Junos Basics – OSPF

Oh, my.  Another Junos post.  Somebody stop me before I get my JNCIA!

This isn’t hard stuff at all.  I’m sure there are a couple of cool tricks I don’t know yet, but let’s try anyway.  I”m working on an SRX240 here running 11.1 and some change.

Let’s put interfaces ge-0/0/0.0 and lo0.0 in OSPF area 0. If you know the Junos configuration hierarchy, this will be very easy to you. Even if you don’t, you can stare at the config for a little bit and see what we’re doing.

This is the only OSPF configuration you need, but guess what?  It won’t work.  Since a Junos device is also a firewall, it will drop OSPF packets as they come into the interface; you have to declare that you do indeed want to accept OSPF packets.  You do this by creating a security zone, putting the right interfaces in the right zone, and then enabling OSPF on that zone.

We’ll create a zone called INSIDE for our purposes here.  Note that there are about billion more steps (I counted) to fully configure your security zones, but that’s way beyond our scope here.

You can also allow OSPF on specific interfaces like this. These commands will also put those interfaces in the right security zone.

I’m not sure if you need to do this to lo0.0, but it won’t hurt.

Now you can see your OSPF neighbors come up and start exchanging routing information.  That is, of course, assuming you did everything else right.

Send any blog deadlines questions my way.

Aaron Conaway

I shake my head around sometimes and see what falls out. That's what lands on these pages. If you have any questions, the best way to contact me is through Twitter at @aconaway.

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